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Hexaphosphabenzene

January 01, 1970

Hexaphosphabenzene is a valence isoelectronic analogue of benzene and is expected to have a similar planar structure due to resonance stabilization and its sp2 nature. Although several other allotropes of phosphorus are stable, no evidence for the existence of P6 has been reported. Preliminary ab initio calculations on the trimerisation of P2 leading to the formation of the cyclic P6 were performed, and it was predicted that hexaphosphabenzene would decompose to free P2 with an energy barrier of 13−15.4 kcal mol−1,[1] and would therefore not be observed in the uncomplexed state under normal experimental conditions. The presence of an added solvent, such as ethanol, might lead to the formation of intermolecular hydrogen bonds which may block the destabilizing interaction between phosphorus lone pairs and consequently stabilize P6.[1] The moderate barrier suggests that hexaphosphabenzene could be synthesized from a [2+2+2] cycloaddition of three P2 molecules.[2] Currently, this is a synthetic endeavour which remains to be conquered.

Hexaphosphabenzene

Depiction of the all-phosphorus analogue of benzene
Names
IUPAC name
hexaphosphinine
Identifiers
  • 15924-07-9
3D model (JSmol)
  • Interactive image
ChemSpider
  • 26667764
  • 15301818
  • DTXSID80571147
  • InChI=1S/P6/c1-2-4-6-5-3-1
    Key: LUXLNUKEFPPPIN-UHFFFAOYSA-N
  • P1=PP=PP=P1
Properties
P6
Molar mass 185.842571988 g·mol−1
Related compounds
Related compounds
 Benzene
Hexazine
Borazine
Carborazine
Aluminazine
Caraluminazine
Except where otherwise noted, data are given for materials in their standard state (at 25 °C [77 °F], 100 kPa).

Synthesis edit

 
Structure of [{(η5-Me5C5)Mo}2(μ,η6-P6)

Isolation of hexaphosphabenzene was first achieved within a triple-decker sandwich complex in 1985 by Scherer et al. Amber coloured, air-stable crystals of [{(η5-Me5C5)Mo}2(μ,η6-P6)] are formed by reaction of [CpMo(CO)2/3]2 with excess P4 in dimethylbenzene, albeit with a yield of approximately 1%.[clarification needed][3][4] The crystal structure of this complex is a centrosymmetric molecule, and both five-membered rings as well as the central bridge-ligand P6 ring are planar and parallel. The average P–P distance for the hexaphosphabenzene within this complex is 2.170 Å.[3][5]

Thirty years later, Fleischmann et al. improved the synthetic yield of [{(η5-Me5C5)Mo}2(μ,η6-P6)] up to 64%. This was achieved by increasing the reaction temperature of the thermolysis of [CpMo(CO)2/3]2 with P4 to approximately 205 °C in boiling diisopropylbenzene, thus favouring the formation of [{(η5-Me5C5)Mo}2(μ,η6-P6)] as the thermodynamic product.[6]

Several analogues of this P6 triple‐decker complex where the coordinating metal and η5-ligand has been varied have also been reported. These include P6 triple‐decker complexes for Ti, V, Nb, and W, whereby the synthetic method is still based on the originally reported thermolysis of [CpM(CO)2/3]2 with P4.[7][8][9][10][11]

Electron count edit

 
The dominant MOs responsible for ligand metal interactions in the triple-decker sandwich complexes, imposed on a qualitative energy diagram for [{(η5-Cp)Mo}2(μ,η6-P6)]
 
Geometry of the middle P6 ring in triple-decker sandwich complexes with 28, 26, and 24 valence electron counts

If one regards the planar P6 ring as a 6π electron donor ligand, then [{(η5-Me5C5)Mo}2(μ,η6-P6)] is a triple-decker sandwich complex with 28 valence electrons. If P6, similar to C6H6, is taken as a 10π electron donor, a 32 valence electron count may be obtained. In most triple-decker complexes with an electron count ranging from 26 to 34, the structure of the middle ring is planar ([{(η5-Cp)M}2(μ,η6-P6)] with M = Mo, Sc, Y, Zr, Hf, V, Nb, Ta, Cr, and W).[12][13] In the 24 valence electron [{(η5-Cp)Ti}2(μ,η6-P6)] complex, however, a distortion is observed, and the P6 ring is puckered.[7]

Calculations have concluded that completely filled 2a*and 2b* orbitals in 28 valence electron complexes lead to a planar symmetrical P6 middle ring. In 26 valence electron complexes, the occupancy of either 2a*or 2b* results in in-plane or bisallylic distortions and an asymmetric planar middle ring. The puckering of P6 in 24 valence electron complexes is due to the stabilization of 5a, as well as that conferred by the tetravalent oxidation state of Ti in [{(η5-Cp)Ti}2(μ,η6-P6)].[7][14]

Reactivity edit

 
Bisallylic distorted P6 ligand within the molecular structure of the [[{(η5- Me5C5)Mo}2(μ,η6-P6)]]+ cation

One-electron oxidation edit

The reactivity of [{(η5- Me5C5)Mo}2(μ,η6-P6)] toward silver and copper monocationic salts of the weakly coordinating anion [Al{OC(CF3)3}4]− ([TEF]) was studied by Fleischmann et al. in 2015.[6] Addition of a solution of Ag[TEF] or Cu[TEF] to a solution of [{(η5- Me5C5)Mo}2(μ,η6-P6)] in chloroform results in oxidation of the complex, which can be observed by an immediate colour change from amber to dark teal. The magnetic moment of the dark teal crystals determined by the Evans NMR method is equal to 1.67 μB, which is consistent with one unpaired electron. Accordingly, [{(η5- Me5C5)Mo}2(μ,η6-P6)]+ is detected by ESI mass spectrometry.

The crystal structure of the teal product shows that the triple‐decker geometry is retained during the one‐electron oxidation of [{(η5- Me5C5)Mo}2(μ,η6-P6)]. The Mo—Mo bond length of the [{(η5- Me5C5)Mo}2(μ,η6-P6)]+ cation is 2.6617(4) Å; almost identical to the bond length determined for the unoxidized species at 2.6463(3) Å. However, the P—P bond lengths are strongly affected by the oxidation. While the P1—P1′ and P3—P3′ bonds are elongated, the remaining P—P bonds are shortened compared to the average P—P bond length of about 2.183 Å in the unoxidized species. Therefore, the middle deck of the 27 valence electron [{(η5- Me5C5)Mo}2(μ,η6-P6)]+ complex can best be described as a bisallylic distorted P6 ligand, intermediate between the 28 valence electron complexes with a perfectly planar symmetrical ring, and those with 26 valence electrons displaying a more amplified in-plane distortion. Density functional theorem (DFT) calculations confirm that this distortion is due to depopulation of the P bonding orbitals upon oxidation of the triple-decker sandwich complex.[6]

Cu[TEF] & Ag[TEF] edit

 
Reactivity of [{(η5- Me5C5)Mo}2(μ,η6-P6)] towards the cations Cu+, Ag+, and Tl+

To avoid oxidation of [{(η5- Me5C5)Mo}2(μ,η6-P6)], further reactions were performed in toluene to decrease the redox potential of the cations. This resulted in a bright orange coordination product upon reaction with copper, although a mixture also containing the dark teal oxidation product was obtained upon reaction with silver.

Single‐crystal X‐ray analysis reveals that this product displays a distorted square‐planar coordination environment around the central cation through two side‐on coordinating P—P bonds. The Ag—P distances are approximately 2.6 Å, whereas the Cu—P distances are determined to be approximately 2.4 Å. The P—P bonds are therefore elongated to 2.2694(16) Å and 2.2915(14) Å upon coordination to copper and silver, respectively, whilst the remaining P—P bonds are unaffected.

In another experiment Cu[TEF] is treated with [{(η5- Me5C5)Mo}2(μ,η6-P6)] in pure toluene and the solution shows the bright orange color of the complex cation [Cu([{(η5- Me5C5)Mo}2(μ,η6-P6)])2]+. However, analysis of crystals from this solution reveals a distorted tetrahedral coordination environment around Cu. The resulting Cu—P distances are somewhat shorter than their counterparts discussed above. The coordinating P—P bonds are a little longer, which is attributed to less steric crowding in the tetrahedral coordination geometry around the Cu center.

The successful isolation of [Cu([{(η5- Me5C5)Mo}2(μ,η6-P6)])2]+ either as its tetrahedral or square‐planar isomer is therefore achievable. DFT calculations show that the enthalpy for the tetrahedral to square‐planar isomerization is positive for both metals, with the tetrahedral coordination being favored. When entropy is taken into account, small positive values for Cu+ and larger, but negative, values for Ag+ are observed. This means that the tetrahedral geometry is predominant for Cu+, but a significant percentage of the complexes adopt a square‐planar geometry in solution. For Ag+, the equilibrium is shifted significantly to the right side, which is presumably why a tetrahedral coordination of [{(η5- Me5C5)Mo}2(μ,η6-P6)] and Ag+ has not yet been observed.

Examination of the crystal packing reveals that these products are layered compounds that crystallize in the monoclinic C2/c space group with alternating negatively charged layers of the [TEF] anions and positively charged layers of isolated [M([{(η5- Me5C5)Mo}2(μ,η6-P6)])2]+ complexes. The layers lie inside the bc plane, alternate along the a axis, and do not form a two‐dimensional network.[6]

Tl[TEF] edit

The treatment of [{(η5- Me5C5)Mo}2(μ,η6-P6)] with Tl[TEF] in chloroform gives an immediate color change from amber to a deep red. The crystal structure reveals a trigonal pyramidal coordination of the thallium cation, Tl+, by three side‐on coordinating P—P bonds of the P6 ligands. Two of these P6 ligands show shorter and uniform Tl—P distances of 3.2–3.3 Å with P—P bonds elongated to about 2.22 Å, whilst the third unit shows an unsymmetrical coordination with long Tl—P distances of approximately 3.42 and 3.69 Å and no P—P bond elongation.

 
Crystal packing of a) [Ag([{(η5- Me5C5)Mo}2(μ,η6-P6)])2]+and b) [Tl([{(η5- Me5C5)Mo}2(μ,η6-P6)])2]+ showing the alternation of anionic and cationic layers along the a axis. Tl+ positions are half‐occupied.

Although the environment of Tl+ is distinctly different from that of Cu+ and Ag+, their structures are related by the two‐dimensional coordination network that propagates inside the bc plane. Crucially, whilst Cu+ and Ag+ form layered structures with isolated [M([{(η5- Me5C5)Mo}2(μ,η6-P6)])2]+ complex cations, there is a statistical distribution of the Tl+ cations inside the two‐dimensional coordination, which shows further interconnection of the P6 ligands to form an extended 2D network that could be regarded as a supramolecular analogue of graphene.[6]

Jahn–Teller distortion edit

 
Representative structures of P6. Included are point group symmetries and relative energies.

Despite the triple-decker sandwich complex {(η5-Me5C5)Mo}2(μ,η6-P6) containing a demonstrably planar P6 ring with equal P—P bond lengths, theoretical calculations reveal that there are at least 7 non-planar P6 isomers lower in energy than the planar benzene-like D6h structure.[1][2][15][16][17][18][19][20][21][22][23][24] In increasing order of energy these are: benzvalene, prismane, chair, Dewar benzene, bicyclopropenyl, distorted benzene, and benzene.[24]

 
Interaction of the pairs of occupied and unoccupied molecular orbitals of P6 responsible for the distortion of the planar D6h structure toward the distorted D2 structure

A pseudo Jahn–Teller effect (PJT) is responsible for distortion of the D6h benzene-like structure into the D2 structure,[25][26][27][28][29][30] which occurs along the e2u doubly degenerate mode as a result of vibronic coupling of the HOMO − 1 (e2g) and LUMO (e2u): e2g ⊗ e2u = a1u ⊕ a2u ⊕ e2u. The distorted structure is calculated to lie just 2.7 kcal mol−1 lower in energy than the D6h structure. If the uncomplexed structure were to be successfully synthesized, the aromaticity of the benzene-like P6 structure would not be sufficient to stabilize the planar geometry, and the PJT effect would result in distortion of the ring.[31]

Isomers edit

 
Chemical bonding picture of g). AdNDP analysis performed by Galeev and Boldyrev.

Adaptive Natural Density Partitioning (AdNDP) is a theoretical tool developed by Alexander Boldyrev that is based on the concept of the electron pair as the main element of chemical bonding models. It can therefore recover Lewis bonding elements such as 1c–2e core electrons and lone pairs, 2c–2e objects which are two-center two-electron bonds, as well as delocalized many-center bonding elements with respect to aromaticity.

The AdNDP analysis of the seven representative low-lying P6 structures reveal that these are well described by the classical Lewis model. A lone pair on each phosphorus atom, a two-center-two-electron (2c–2e) σ-bond in every pair of adjacent P atoms, and an additional 2c–2e π-bond between adjacent 2-coordinated P atoms are found, with occupation numbers (ON) of all these bonding elements above 1.92 |e|.[31]

The chemical bonding in the chair structure is unusual. Based on fragment orbital analysis, it was concluded that two linkages between the two P3 fragments are of the one-electron hemibond type. The AdNDP analysis reveals a lone pair on each P atom and six 2c–2e P—P σ-bonds. One 3c–2e π-bond in every P3 triangle was revealed with the user-directed form of the AdNDP analysis, as well as a 4c–2e bond responsible for bonding between the two P3 triangle, confirming that this isomer cannot be represented by a single Lewis structure, and requires a resonance of two Lewis structures, or can be described by a single formula with delocalized bonding elements.

Both the D6h benzene-like structure, as well as the D2 isomer of P6 is similar to the reported AdNDP bonding pattern of the C6H6 benzene molecule:[32] 2c–2e σ-bond and lone pairs, as well as delocalized 6c-2e π-bonds. The distortion due to the PJT effect therefore does not significantly disturb the bonding picture.[31]

Suppression edit

 
Suppression of the pseudo Jahn–Teller effect in P6 upon complexation in a sandwich compound
 
Correspondence of unoccupied molecular orbitals of P6 to those of [{(η5- Me5C5)Mo}2(μ,η6-P6)]. Occupation in the latter results in suppression of the PJT effect.

The planar P6 hexagonal structure D6h is a second-order saddle point due to the pseudo-Jahn–Teller effect (PJT), which leads to the D2 distorted structure. Upon sandwich complex formation the PJT effect is suppressed due to filling of the unoccupied molecular orbitals involved in vibronic coupling in P6 with electron pairs of Mo atoms.[33][34][35] Specifically, from molecular orbital analysis it was determined that, upon complex formation, the LUMO in the isolated P6 structure is now occupied in the triple-decker complex as a result of the appreciable δ-type M → L back-donation mechanism from the occupied dx2–y2 and dxy atomic orbitals of the Mo atom into the partially antibonding π molecular orbitals of P6, thus restoring the high symmetry and planarity of P6.[35]

References edit

  1. ^ a b c Nguyen, Minh Tho; Hegarty, Anthony F. (1986-01-01). "Can the cyclic hexaphosphabenzene (P6) exist?". Journal of the Chemical Society, Chemical Communications (5): 383–385. doi:10.1039/C39860000383. ISSN 0022-4936.
  2. ^ a b Nagase, Shigeru; Ito, Keiji (1986-04-25). "Theoretical study of hexaphosphabenzene and its valence isomers. Is cyclic P6 stable?". Chemical Physics Letters. 126 (1): 43–47. Bibcode:1986CPL...126...43N. doi:10.1016/0009-2614(86)85113-2. ISSN 0009-2614.
  3. ^ a b Scherer, Otto J.; Sitzmann, Helmut; Wolmershäuser, Gotthelf (1985). "Hexaphosphabenzene as Complex Ligand". Angewandte Chemie International Edition in English. 24 (4): 351–353. doi:10.1002/anie.198503511. ISSN 1521-3773.
  4. ^ Meier, Herbert; Zeller, Klaus-Peter (1975). "The Wolff Rearrangement of α-Diazo Carbonyl Compounds". Angewandte Chemie International Edition in English. 14 (1): 32–43. doi:10.1002/anie.197500321. ISSN 1521-3773.
  5. ^ Scherer, Otto J. (2000). "Small Neutral Pn Molecules". Angewandte Chemie International Edition. 39 (6): 1029–1030. doi:10.1002/(SICI)1521-3773(20000317)39:6<1029::AID-ANIE1029>3.0.CO;2-6. ISSN 1521-3773. PMID 10760912.
  6. ^ a b c d e Fleischmann, Martin; Dielmann, Fabian; Gregoriades, Laurence J.; Peresypkina, Eugenia V.; Virovets, Alexander V.; Huber, Sebastian; Timoshkin, Alexey Y.; Balázs, Gábor; Scheer, Manfred (2015). "Redox and Coordination Behavior of the Hexaphosphabenzene Ligand in [(Cp*Mo)2(μ,η6:η6-P6)] Towards the "Naked" Cations Cu+, Ag+, and Tl+". Angewandte Chemie International Edition. 54 (44): 13110–13115. doi:10.1002/anie.201506362. ISSN 1521-3773. PMC 4675074. PMID 26337857.
  7. ^ a b c Scherer, Otto J.; Swarowsky, Herbert; Wolmershäuser, Gotthelf; Kaim, Wolfgang; Kohlmann, Stephan (1987). "[(η5-C5Me5)2 Ti2P6], a Distorted Dimetallaphosphacubane". Angewandte Chemie International Edition in English. 26 (11): 1153–1155. doi:10.1002/anie.198711531. ISSN 1521-3773.
  8. ^ Herberhold, Max; Frohmader, Gudrun; Milius, Wolfgang (1996-09-20). "Neue vanadium-komplexe mit substituentenfreien phosphorliganden". Journal of Organometallic Chemistry (in German). 522 (2): 185–196. doi:10.1016/0022-328X(96)06305-X. ISSN 0022-328X.
  9. ^ Scherer, Otto J.; Schwalb, Joachim; Swarowsky, Herbert; Wolmershäuser, Gotthelf; Kaim, Wolfgang; Gross, Renate (1988-03-01). "Tripeldecker-Sandwichkomplexe mit cyclo-P6-Mitteldeck". Chemische Berichte. 121 (3): 443–449. doi:10.1002/cber.19881210309. ISSN 0009-2940.
  10. ^ Scherer, Otto J.; Vondung, Jürgen; Wolmershäuser, Gotthelf (1989). "Tetraphosphacyclobutadiene as Complex Ligand". Angewandte Chemie International Edition in English. 28 (10): 1355–1357. doi:10.1002/anie.198913551. ISSN 1521-3773.
  11. ^ Reddy, A. Chandrasekhar; Jemmis, Eluvathingal D.; Scherer, Otto J.; Winter, Rainer; Heckmann, Gert; Wolmershaeuser, Gotthelf (1992-11-01). "Electronic structure of triple-decker sandwich complexes with P6 middle rings. Synthesis and x-ray structure determination of bis(.eta.5-1,3-di-tert-butylcyclopentadienyl)(.mu.-.eta.6:.eta.6-hexaphosphorin)diniobium". Organometallics. 11 (11): 3894–3900. doi:10.1021/om00059a064. ISSN 0276-7333.
  12. ^ Jemmis, Eluvathingal D.; Reddy, A. Chandrasekhar. (1988-07-01). "Electronic structure of triple-decker sandwich compounds with P5, P6, As5, and CnHn as middle rings". Organometallics. 7 (7): 1561–1564. doi:10.1021/om00097a019. ISSN 0276-7333.
  13. ^ Jemmis, Eluvathingal D.; Reddy, A. Chandrasekhar (1990-06-01). "Structure and bonding in metallocenes and oligomers" (PDF). Proceedings of the Indian Academy of Sciences - Chemical Sciences. 102 (3): 379–393. doi:10.1007/BF02841950. ISSN 0973-7103. S2CID 92733876.
  14. ^ Rani, Dandamudi Usha; Prasad, Dasari L. V. K.; Nixon, John F.; Jemmis, Eluvathingal D. (2007). "Electronic structure and bonding studies on triple-decker sandwich complexes with a P6 middle ring". Journal of Computational Chemistry. 28 (1): 310–319. doi:10.1002/jcc.20521. ISSN 1096-987X. PMID 17103397. S2CID 25386398.
  15. ^ Jones, R.; Hohl, D. (1990). "Structure of phosphorus clusters using simulated annealing—P2 to P8". The Journal of Chemical Physics. 92 (11): 6710–6721. Bibcode:1990JChPh..92.6710J. doi:10.1063/1.458306. S2CID 31227289.
  16. ^ Jones, R. O.; Ganteför, G.; Hunsicker, S.; Pieperhoff, P. (1995-12-08). "Structure and spectroscopy of phosphorus cluster anions: Theory (simulated annealing) and experiment (photoelectron detachment)". The Journal of Chemical Physics. 103 (22): 9549–9562. Bibcode:1995JChPh.103.9549J. doi:10.1063/1.469969. ISSN 0021-9606.
  17. ^ Warren, D. Scott; Gimarc, Benjamin M. (1992-06-01). "Valence isomers of benzene and their relationship to isomers of isoelectronic P6". Journal of the American Chemical Society. 114 (13): 5378–5385. doi:10.1021/ja00039a058. ISSN 0002-7863.
  18. ^ Olvera de la Cruz, M.; Mayes, A. M.; Swift, B. W. (1992-01-01). "Transition to lamellar-catenoid structure in block-copolymer melts". Macromolecules. 25 (2): 944–948. Bibcode:1992MaMol..25..944O. doi:10.1021/ma00028a067. ISSN 0024-9297.
  19. ^ Haeser, Marco; Schneider, Uwe; Ahlrichs, Reinhart (1992-11-01). "Clusters of phosphorus: a theoretical investigation". Journal of the American Chemical Society. 114 (24): 9551–9559. doi:10.1021/ja00050a039. ISSN 0002-7863.
  20. ^ Jones, J. L.; Olvera de la Cruz, M. (1994-04-01). "Transitions to periodic structures: Higher harmonic corrections with concentration fluctuations". The Journal of Chemical Physics. 100 (7): 5272–5279. Bibcode:1994JChPh.100.5272J. doi:10.1063/1.467191. ISSN 0021-9606.
  21. ^ Häser, Marco; Treutler, Oliver (1995-03-01). "Calculated properties of P2, P4, and of closed-shell clusters up to P18". The Journal of Chemical Physics. 102 (9): 3703–3711. Bibcode:1995JChPh.102.3703H. doi:10.1063/1.468552. ISSN 0021-9606.
  22. ^ Kobayashi, Kaoru; Miura, Hideki; Nagase, Shigeru (1994-07-20). "The heavier group 15 analogues of benzene, cyclobutadiene and their valence isomers (M6 and M4, M = P, As, Sb and Bi)". Journal of Molecular Structure: THEOCHEM. 311: 69–77. doi:10.1016/S0166-1280(09)80043-2. ISSN 0166-1280.
  23. ^ Ballone, P.; Jones, R. O. (1994-04-01). "Density functional study of phosphorus and arsenic clusters using local and nonlocal energy functionals". The Journal of Chemical Physics. 100 (7): 4941–4946. Bibcode:1994JChPh.100.4941B. doi:10.1063/1.467213. ISSN 0021-9606.
  24. ^ a b Hiberty, Philippe C.; Volatron, François (2007). "Ab initio conformational study of the P6 potential surface: Evidence for a low-lying one-electron-bonded isomer". Heteroatom Chemistry. 18 (2): 129–134. doi:10.1002/hc.20324. ISSN 1098-1071.
  25. ^ Bersuker, Isaac B. (2001-04-01). "Modern Aspects of the Jahn−Teller Effect Theory and Applications To Molecular Problems". Chemical Reviews. 101 (4): 1067–1114. doi:10.1021/cr0004411. ISSN 0009-2665. PMID 11709858.
  26. ^ Bersuker, I. B. The Jahn–Teller effect. Cambridge. ISBN 978-0-511-52476-9. OCLC 967605700.
  27. ^ Isaak Borisovich Bersuker (2008). The Jahn–Teller Effect and Beyond: Selected Works of Isaac Bersuker with Commentaries : Dedicated to Isaac B. Bersuker on Occasion of His 80th Birthday. Academy of Sciences of Moldova. ISBN 978-9975-62-212-7.
  28. ^ Pearson, Ralph G. (1975-06-01). "Concerning Jahn–Teller Effects". Proceedings of the National Academy of Sciences. 72 (6): 2104–2106. Bibcode:1975PNAS...72.2104P. doi:10.1073/pnas.72.6.2104. ISSN 0027-8424. PMC 432704. PMID 16592247.
  29. ^ Bersuker, I. B. (1966-04-01). "On the origin of ferroelectricity in perovskite-type crystals". Physics Letters. 20 (6): 589–590. Bibcode:1966PhL....20..589B. doi:10.1016/0031-9163(66)91127-9. ISSN 0031-9163.
  30. ^ Öpik, U.; Pryce, Maurice Henry Lecorney (1957-01-29). "Studies of the Jahn–Teller effect. I. A survey of the static problem". Proceedings of the Royal Society of London. Series A. Mathematical and Physical Sciences. 238 (1215): 425–447. Bibcode:1957RSPSA.238..425O. doi:10.1098/rspa.1957.0010. S2CID 119862339.
  31. ^ a b c Galeev, Timur R.; Boldyrev, Alexander I. (2011-11-15). "Planarity takes over in the CxHxP6−x (x = 0–6) series at x = 4". Physical Chemistry Chemical Physics. 13 (46): 20549–20556. Bibcode:2011PCCP...1320549G. doi:10.1039/C1CP21959F. ISSN 1463-9084. PMID 21869975.
  32. ^ Zubarev, Dmitry Yu.; Boldyrev, Alexander I. (2008-12-05). "Revealing Intuitively Assessable Chemical Bonding Patterns in Organic Aromatic Molecules via Adaptive Natural Density Partitioning". The Journal of Organic Chemistry. 73 (23): 9251–9258. doi:10.1021/jo801407e. ISSN 0022-3263. PMID 18980326.
  33. ^ Sergeeva, Alina P.; Boldyrev, Alexander I. (2010-09-13). "Flattening a Puckered Pentasilacyclopentadienide Ring by Suppression of the Pseudo Jahn−Teller Effect". Organometallics. 29 (17): 3951–3954. doi:10.1021/om1006038. ISSN 0276-7333.
  34. ^ Pokhodnya, Konstantin; Olson, Christopher; Dai, Xuliang; Schulz, Douglas L.; Boudjouk, Philip; Sergeeva, Alina P.; Boldyrev, Alexander I. (2011-01-07). "Flattening a puckered cyclohexasilane ring by suppression of the pseudo-Jahn–Teller effect". The Journal of Chemical Physics. 134 (1): 014105. Bibcode:2011JChPh.134a4105P. doi:10.1063/1.3516179. ISSN 0021-9606. PMID 21218995.
  35. ^ a b Ivanov, Alexander S.; Bozhenko, Konstantin V.; Boldyrev, Alexander I. (2012-08-20). "On the Suppression Mechanism of the Pseudo-Jahn–Teller Effect in Middle E6 (E = P, As, Sb) Rings of Triple-Decker Sandwich Complexes". Inorganic Chemistry. 51 (16): 8868–8872. doi:10.1021/ic300786w. ISSN 0020-1669. PMID 22845625.

January 01, 1970
hexaphosphabenzene, this, article, technical, most, readers, understand, please, help, improve, make, understandable, experts, without, removing, technical, details, august, 2022, learn, when, remove, this, message, valence, isoelectronic, analogue, benzene, e. This article may be too technical for most readers to understand Please help improve it to make it understandable to non experts without removing the technical details August 2022 Learn how and when to remove this message Hexaphosphabenzene is a valence isoelectronic analogue of benzene and is expected to have a similar planar structure due to resonance stabilization and its sp2 nature Although several other allotropes of phosphorus are stable no evidence for the existence of P6 has been reported Preliminary ab initio calculations on the trimerisation of P2 leading to the formation of the cyclic P6 were performed and it was predicted that hexaphosphabenzene would decompose to free P2 with an energy barrier of 13 15 4 kcal mol 1 1 and would therefore not be observed in the uncomplexed state under normal experimental conditions The presence of an added solvent such as ethanol might lead to the formation of intermolecular hydrogen bonds which may block the destabilizing interaction between phosphorus lone pairs and consequently stabilize P6 1 The moderate barrier suggests that hexaphosphabenzene could be synthesized from a 2 2 2 cycloaddition of three P2 molecules 2 Currently this is a synthetic endeavour which remains to be conquered Hexaphosphabenzene Depiction of the all phosphorus analogue of benzene Names IUPAC name hexaphosphinine Identifiers CAS Number 15924 07 9 3D model JSmol Interactive image ChemSpider 26667764 PubChem CID 15301818 CompTox Dashboard EPA DTXSID80571147 InChI InChI 1S P6 c1 2 4 6 5 3 1Key LUXLNUKEFPPPIN UHFFFAOYSA N SMILES P1 PP PP P1 Properties Chemical formula P 6 Molar mass 185 842571 988 g mol 1 Related compounds Related compounds BenzeneHexazineBorazineCarborazineAluminazineCaraluminazine Except where otherwise noted data are given for materials in their standard state at 25 C 77 F 100 kPa Infobox references Contents 1 Synthesis 2 Electron count 3 Reactivity 3 1 One electron oxidation 3 2 Cu TEF amp Ag TEF 3 3 Tl TEF 4 Jahn Teller distortion 4 1 Isomers 4 2 Suppression 5 ReferencesSynthesis edit nbsp Structure of h5 Me5C5 Mo 2 m h6 P6 Isolation of hexaphosphabenzene was first achieved within a triple decker sandwich complex in 1985 by Scherer et al Amber coloured air stable crystals of h5 Me5C5 Mo 2 m h6 P6 are formed by reaction of CpMo CO 2 3 2 with excess P4 in dimethylbenzene albeit with a yield of approximately 1 clarification needed 3 4 The crystal structure of this complex is a centrosymmetric molecule and both five membered rings as well as the central bridge ligand P6 ring are planar and parallel The average P P distance for the hexaphosphabenzene within this complex is 2 170 A 3 5 Thirty years later Fleischmann et al improved the synthetic yield of h5 Me5C5 Mo 2 m h6 P6 up to 64 This was achieved by increasing the reaction temperature of the thermolysis of CpMo CO 2 3 2 with P4 to approximately 205 C in boiling diisopropylbenzene thus favouring the formation of h5 Me5C5 Mo 2 m h6 P6 as the thermodynamic product 6 Several analogues of this P6 triple decker complex where the coordinating metal and h5 ligand has been varied have also been reported These include P6 triple decker complexes for Ti V Nb and W whereby the synthetic method is still based on the originally reported thermolysis of CpM CO 2 3 2 with P4 7 8 9 10 11 Electron count edit nbsp The dominant MOs responsible for ligand metal interactions in the triple decker sandwich complexes imposed on a qualitative energy diagram for h5 Cp Mo 2 m h6 P6 nbsp Geometry of the middle P6 ring in triple decker sandwich complexes with 28 26 and 24 valence electron counts If one regards the planar P6 ring as a 6p electron donor ligand then h5 Me5C5 Mo 2 m h6 P6 is a triple decker sandwich complex with 28 valence electrons If P6 similar to C6H6 is taken as a 10p electron donor a 32 valence electron count may be obtained In most triple decker complexes with an electron count ranging from 26 to 34 the structure of the middle ring is planar h5 Cp M 2 m h6 P6 with M Mo Sc Y Zr Hf V Nb Ta Cr and W 12 13 In the 24 valence electron h5 Cp Ti 2 m h6 P6 complex however a distortion is observed and the P6 ring is puckered 7 Calculations have concluded that completely filled 2a and 2b orbitals in 28 valence electron complexes lead to a planar symmetrical P6 middle ring In 26 valence electron complexes the occupancy of either 2a or 2b results in in plane or bisallylic distortions and an asymmetric planar middle ring The puckering of P6 in 24 valence electron complexes is due to the stabilization of 5a as well as that conferred by the tetravalent oxidation state of Ti in h5 Cp Ti 2 m h6 P6 7 14 Reactivity edit nbsp Bisallylic distorted P6 ligand within the molecular structure of the h5 Me5C5 Mo 2 m h6 P6 cation One electron oxidation edit The reactivity of h5 Me5C5 Mo 2 m h6 P6 toward silver and copper monocationic salts of the weakly coordinating anion Al OC CF3 3 4 TEF was studied by Fleischmann et al in 2015 6 Addition of a solution of Ag TEF or Cu TEF to a solution of h5 Me5C5 Mo 2 m h6 P6 in chloroform results in oxidation of the complex which can be observed by an immediate colour change from amber to dark teal The magnetic moment of the dark teal crystals determined by the Evans NMR method is equal to 1 67 mB which is consistent with one unpaired electron Accordingly h5 Me5C5 Mo 2 m h6 P6 is detected by ESI mass spectrometry The crystal structure of the teal product shows that the triple decker geometry is retained during the one electron oxidation of h5 Me5C5 Mo 2 m h6 P6 The Mo Mo bond length of the h5 Me5C5 Mo 2 m h6 P6 cation is 2 6617 4 A almost identical to the bond length determined for the unoxidized species at 2 6463 3 A However the P P bond lengths are strongly affected by the oxidation While the P1 P1 and P3 P3 bonds are elongated the remaining P P bonds are shortened compared to the average P P bond length of about 2 183 A in the unoxidized species Therefore the middle deck of the 27 valence electron h5 Me5C5 Mo 2 m h6 P6 complex can best be described as a bisallylic distorted P6 ligand intermediate between the 28 valence electron complexes with a perfectly planar symmetrical ring and those with 26 valence electrons displaying a more amplified in plane distortion Density functional theorem DFT calculations confirm that this distortion is due to depopulation of the P bonding orbitals upon oxidation of the triple decker sandwich complex 6 Cu TEF amp Ag TEF edit nbsp Reactivity of h5 Me5C5 Mo 2 m h6 P6 towards the cations Cu Ag and Tl To avoid oxidation of h5 Me5C5 Mo 2 m h6 P6 further reactions were performed in toluene to decrease the redox potential of the cations This resulted in a bright orange coordination product upon reaction with copper although a mixture also containing the dark teal oxidation product was obtained upon reaction with silver Single crystal X ray analysis reveals that this product displays a distorted square planar coordination environment around the central cation through two side on coordinating P P bonds The Ag P distances are approximately 2 6 A whereas the Cu P distances are determined to be approximately 2 4 A The P P bonds are therefore elongated to 2 2694 16 A and 2 2915 14 A upon coordination to copper and silver respectively whilst the remaining P P bonds are unaffected In another experiment Cu TEF is treated with h5 Me5C5 Mo 2 m h6 P6 in pure toluene and the solution shows the bright orange color of the complex cation Cu h5 Me5C5 Mo 2 m h6 P6 2 However analysis of crystals from this solution reveals a distorted tetrahedral coordination environment around Cu The resulting Cu P distances are somewhat shorter than their counterparts discussed above The coordinating P P bonds are a little longer which is attributed to less steric crowding in the tetrahedral coordination geometry around the Cu center The successful isolation of Cu h5 Me5C5 Mo 2 m h6 P6 2 either as its tetrahedral or square planar isomer is therefore achievable DFT calculations show that the enthalpy for the tetrahedral to square planar isomerization is positive for both metals with the tetrahedral coordination being favored When entropy is taken into account small positive values for Cu and larger but negative values for Ag are observed This means that the tetrahedral geometry is predominant for Cu but a significant percentage of the complexes adopt a square planar geometry in solution For Ag the equilibrium is shifted significantly to the right side which is presumably why a tetrahedral coordination of h5 Me5C5 Mo 2 m h6 P6 and Ag has not yet been observed Examination of the crystal packing reveals that these products are layered compounds that crystallize in the monoclinic C2 c space group with alternating negatively charged layers of the TEF anions and positively charged layers of isolated M h5 Me5C5 Mo 2 m h6 P6 2 complexes The layers lie inside the bc plane alternate along the a axis and do not form a two dimensional network 6 Tl TEF edit The treatment of h5 Me5C5 Mo 2 m h6 P6 with Tl TEF in chloroform gives an immediate color change from amber to a deep red The crystal structure reveals a trigonal pyramidal coordination of the thallium cation Tl by three side on coordinating P P bonds of the P6 ligands Two of these P6 ligands show shorter and uniform Tl P distances of 3 2 3 3 A with P P bonds elongated to about 2 22 A whilst the third unit shows an unsymmetrical coordination with long Tl P distances of approximately 3 42 and 3 69 A and no P P bond elongation nbsp Crystal packing of a Ag h5 Me5C5 Mo 2 m h6 P6 2 and b Tl h5 Me5C5 Mo 2 m h6 P6 2 showing the alternation of anionic and cationic layers along the a axis Tl positions are half occupied Although the environment of Tl is distinctly different from that of Cu and Ag their structures are related by the two dimensional coordination network that propagates inside the bc plane Crucially whilst Cu and Ag form layered structures with isolated M h5 Me5C5 Mo 2 m h6 P6 2 complex cations there is a statistical distribution of the Tl cations inside the two dimensional coordination which shows further interconnection of the P6 ligands to form an extended 2D network that could be regarded as a supramolecular analogue of graphene 6 Jahn Teller distortion edit nbsp Representative structures of P6 Included are point group symmetries and relative energies Despite the triple decker sandwich complex h5 Me5C5 Mo 2 m h6 P6 containing a demonstrably planar P6 ring with equal P P bond lengths theoretical calculations reveal that there are at least 7 non planar P6 isomers lower in energy than the planar benzene like D6h structure 1 2 15 16 17 18 19 20 21 22 23 24 In increasing order of energy these are benzvalene prismane chair Dewar benzene bicyclopropenyl distorted benzene and benzene 24 nbsp Interaction of the pairs of occupied and unoccupied molecular orbitals of P6 responsible for the distortion of the planar D6h structure toward the distorted D2 structure A pseudo Jahn Teller effect PJT is responsible for distortion of the D6h benzene like structure into the D2 structure 25 26 27 28 29 30 which occurs along the e2u doubly degenerate mode as a result of vibronic coupling of the HOMO 1 e2g and LUMO e2u e2g e2u a1u a2u e2u The distorted structure is calculated to lie just 2 7 kcal mol 1 lower in energy than the D6h structure If the uncomplexed structure were to be successfully synthesized the aromaticity of the benzene like P6 structure would not be sufficient to stabilize the planar geometry and the PJT effect would result in distortion of the ring 31 Isomers edit nbsp Chemical bonding picture of g AdNDP analysis performed by Galeev and Boldyrev Adaptive Natural Density Partitioning AdNDP is a theoretical tool developed by Alexander Boldyrev that is based on the concept of the electron pair as the main element of chemical bonding models It can therefore recover Lewis bonding elements such as 1c 2e core electrons and lone pairs 2c 2e objects which are two center two electron bonds as well as delocalized many center bonding elements with respect to aromaticity The AdNDP analysis of the seven representative low lying P6 structures reveal that these are well described by the classical Lewis model A lone pair on each phosphorus atom a two center two electron 2c 2e s bond in every pair of adjacent P atoms and an additional 2c 2e p bond between adjacent 2 coordinated P atoms are found with occupation numbers ON of all these bonding elements above 1 92 e 31 The chemical bonding in the chair structure is unusual Based on fragment orbital analysis it was concluded that two linkages between the two P3 fragments are of the one electron hemibond type The AdNDP analysis reveals a lone pair on each P atom and six 2c 2e P P s bonds One 3c 2e p bond in every P3 triangle was revealed with the user directed form of the AdNDP analysis as well as a 4c 2e bond responsible for bonding between the two P3 triangle confirming that this isomer cannot be represented by a single Lewis structure and requires a resonance of two Lewis structures or can be described by a single formula with delocalized bonding elements Both the D6h benzene like structure as well as the D2 isomer of P6 is similar to the reported AdNDP bonding pattern of the C6H6 benzene molecule 32 2c 2e s bond and lone pairs as well as delocalized 6c 2e p bonds The distortion due to the PJT effect therefore does not significantly disturb the bonding picture 31 Suppression edit nbsp Suppression of the pseudo Jahn Teller effect in P6 upon complexation in a sandwich compound nbsp Correspondence of unoccupied molecular orbitals of P6 to those of h5 Me5C5 Mo 2 m h6 P6 Occupation in the latter results in suppression of the PJT effect The planar P6 hexagonal structure D6h is a second order saddle point due to the pseudo Jahn Teller effect PJT which leads to the D2 distorted structure Upon sandwich complex formation the PJT effect is suppressed due to filling of the unoccupied molecular orbitals involved in vibronic coupling in P6 with electron pairs of Mo atoms 33 34 35 Specifically from molecular orbital analysis it was determined that upon complex formation the LUMO in the isolated P6 structure is now occupied in the triple decker complex as a result of the appreciable d type M L back donation mechanism from the occupied dx2 y2 and dxy atomic orbitals of the Mo atom into the partially antibonding p molecular orbitals of P6 thus restoring the high symmetry and planarity of P6 35 References edit a b c Nguyen Minh Tho Hegarty Anthony F 1986 01 01 Can the cyclic hexaphosphabenzene P6 exist Journal of the Chemical Society Chemical Communications 5 383 385 doi 10 1039 C39860000383 ISSN 0022 4936 a b Nagase Shigeru Ito Keiji 1986 04 25 Theoretical study of hexaphosphabenzene and its valence isomers Is cyclic P6 stable Chemical Physics Letters 126 1 43 47 Bibcode 1986CPL 126 43N doi 10 1016 0009 2614 86 85113 2 ISSN 0009 2614 a b Scherer Otto J Sitzmann Helmut Wolmershauser Gotthelf 1985 Hexaphosphabenzene as Complex Ligand Angewandte Chemie International Edition in English 24 4 351 353 doi 10 1002 anie 198503511 ISSN 1521 3773 Meier Herbert Zeller Klaus Peter 1975 The Wolff Rearrangement of a Diazo Carbonyl Compounds Angewandte Chemie International Edition in English 14 1 32 43 doi 10 1002 anie 197500321 ISSN 1521 3773 Scherer Otto J 2000 Small Neutral Pn Molecules Angewandte Chemie International Edition 39 6 1029 1030 doi 10 1002 SICI 1521 3773 20000317 39 6 lt 1029 AID ANIE1029 gt 3 0 CO 2 6 ISSN 1521 3773 PMID 10760912 a b c d e Fleischmann Martin Dielmann Fabian Gregoriades Laurence J Peresypkina Eugenia V Virovets Alexander V Huber Sebastian Timoshkin Alexey Y Balazs Gabor Scheer Manfred 2015 Redox and Coordination Behavior of the Hexaphosphabenzene Ligand in Cp Mo 2 m h6 h6 P6 Towards the Naked Cations Cu Ag and Tl Angewandte Chemie International Edition 54 44 13110 13115 doi 10 1002 anie 201506362 ISSN 1521 3773 PMC 4675074 PMID 26337857 a b c Scherer Otto J Swarowsky Herbert Wolmershauser Gotthelf Kaim Wolfgang Kohlmann Stephan 1987 h5 C5Me5 2 Ti2P6 a Distorted Dimetallaphosphacubane Angewandte Chemie International Edition in English 26 11 1153 1155 doi 10 1002 anie 198711531 ISSN 1521 3773 Herberhold Max Frohmader Gudrun Milius Wolfgang 1996 09 20 Neue vanadium komplexe mit substituentenfreien phosphorliganden Journal of Organometallic Chemistry in German 522 2 185 196 doi 10 1016 0022 328X 96 06305 X ISSN 0022 328X Scherer Otto J Schwalb Joachim Swarowsky Herbert Wolmershauser Gotthelf Kaim Wolfgang Gross Renate 1988 03 01 Tripeldecker Sandwichkomplexe mit cyclo P6 Mitteldeck Chemische Berichte 121 3 443 449 doi 10 1002 cber 19881210309 ISSN 0009 2940 Scherer Otto J Vondung Jurgen Wolmershauser Gotthelf 1989 Tetraphosphacyclobutadiene as Complex Ligand Angewandte Chemie International Edition in English 28 10 1355 1357 doi 10 1002 anie 198913551 ISSN 1521 3773 Reddy A Chandrasekhar Jemmis Eluvathingal D Scherer Otto J Winter Rainer Heckmann Gert Wolmershaeuser Gotthelf 1992 11 01 Electronic structure of triple decker sandwich complexes with P6 middle rings Synthesis and x ray structure determination of bis eta 5 1 3 di tert butylcyclopentadienyl mu eta 6 eta 6 hexaphosphorin diniobium Organometallics 11 11 3894 3900 doi 10 1021 om00059a064 ISSN 0276 7333 Jemmis Eluvathingal D Reddy A Chandrasekhar 1988 07 01 Electronic structure of triple decker sandwich compounds with P5 P6 As5 and CnHn as middle rings Organometallics 7 7 1561 1564 doi 10 1021 om00097a019 ISSN 0276 7333 Jemmis Eluvathingal D Reddy A Chandrasekhar 1990 06 01 Structure and bonding in metallocenes and oligomers PDF Proceedings of the Indian Academy of Sciences Chemical Sciences 102 3 379 393 doi 10 1007 BF02841950 ISSN 0973 7103 S2CID 92733876 Rani Dandamudi Usha Prasad Dasari L V K Nixon John F Jemmis Eluvathingal D 2007 Electronic structure and bonding studies on triple decker sandwich complexes with a P6 middle ring Journal of Computational Chemistry 28 1 310 319 doi 10 1002 jcc 20521 ISSN 1096 987X PMID 17103397 S2CID 25386398 Jones R Hohl D 1990 Structure of phosphorus clusters using simulated annealing P2 to P8 The Journal of Chemical Physics 92 11 6710 6721 Bibcode 1990JChPh 92 6710J doi 10 1063 1 458306 S2CID 31227289 Jones R O Gantefor G Hunsicker S Pieperhoff P 1995 12 08 Structure and spectroscopy of phosphorus cluster anions Theory simulated annealing and experiment photoelectron detachment The Journal of Chemical Physics 103 22 9549 9562 Bibcode 1995JChPh 103 9549J doi 10 1063 1 469969 ISSN 0021 9606 Warren D Scott Gimarc Benjamin M 1992 06 01 Valence isomers of benzene and their relationship to isomers of isoelectronic P6 Journal of the American Chemical Society 114 13 5378 5385 doi 10 1021 ja00039a058 ISSN 0002 7863 Olvera de la Cruz M Mayes A M Swift B W 1992 01 01 Transition to lamellar catenoid structure in block copolymer melts Macromolecules 25 2 944 948 Bibcode 1992MaMol 25 944O doi 10 1021 ma00028a067 ISSN 0024 9297 Haeser Marco Schneider Uwe Ahlrichs Reinhart 1992 11 01 Clusters of phosphorus a theoretical investigation Journal of the American Chemical Society 114 24 9551 9559 doi 10 1021 ja00050a039 ISSN 0002 7863 Jones J L Olvera de la Cruz M 1994 04 01 Transitions to periodic structures Higher harmonic corrections with concentration fluctuations The Journal of Chemical Physics 100 7 5272 5279 Bibcode 1994JChPh 100 5272J doi 10 1063 1 467191 ISSN 0021 9606 Haser Marco Treutler Oliver 1995 03 01 Calculated properties of P2 P4 and of closed shell clusters up to P18 The Journal of Chemical Physics 102 9 3703 3711 Bibcode 1995JChPh 102 3703H doi 10 1063 1 468552 ISSN 0021 9606 Kobayashi Kaoru Miura Hideki Nagase Shigeru 1994 07 20 The heavier group 15 analogues of benzene cyclobutadiene and their valence isomers M6 and M4 M P As Sb and Bi Journal of Molecular Structure THEOCHEM 311 69 77 doi 10 1016 S0166 1280 09 80043 2 ISSN 0166 1280 Ballone P Jones R O 1994 04 01 Density functional study of phosphorus and arsenic clusters using local and nonlocal energy functionals The Journal of Chemical Physics 100 7 4941 4946 Bibcode 1994JChPh 100 4941B doi 10 1063 1 467213 ISSN 0021 9606 a b Hiberty Philippe C Volatron Francois 2007 Ab initio conformational study of the P6 potential surface Evidence for a low lying one electron bonded isomer Heteroatom Chemistry 18 2 129 134 doi 10 1002 hc 20324 ISSN 1098 1071 Bersuker Isaac B 2001 04 01 Modern Aspects of the Jahn Teller Effect Theory and Applications To Molecular Problems Chemical Reviews 101 4 1067 1114 doi 10 1021 cr0004411 ISSN 0009 2665 PMID 11709858 Bersuker I B The Jahn Teller effect Cambridge ISBN 978 0 511 52476 9 OCLC 967605700 Isaak Borisovich Bersuker 2008 The Jahn Teller Effect and Beyond Selected Works of Isaac Bersuker with Commentaries Dedicated to Isaac B Bersuker on Occasion of His 80th Birthday Academy of Sciences of Moldova ISBN 978 9975 62 212 7 Pearson Ralph G 1975 06 01 Concerning Jahn Teller Effects Proceedings of the National Academy of Sciences 72 6 2104 2106 Bibcode 1975PNAS 72 2104P doi 10 1073 pnas 72 6 2104 ISSN 0027 8424 PMC 432704 PMID 16592247 Bersuker I B 1966 04 01 On the origin of ferroelectricity in perovskite type crystals Physics Letters 20 6 589 590 Bibcode 1966PhL 20 589B doi 10 1016 0031 9163 66 91127 9 ISSN 0031 9163 Opik U Pryce Maurice Henry Lecorney 1957 01 29 Studies of the Jahn Teller effect I A survey of the static problem Proceedings of the Royal Society of London Series A Mathematical and Physical Sciences 238 1215 425 447 Bibcode 1957RSPSA 238 425O doi 10 1098 rspa 1957 0010 S2CID 119862339 a b c Galeev Timur R Boldyrev Alexander I 2011 11 15 Planarity takes over in the CxHxP6 x x 0 6 series at x 4 Physical Chemistry Chemical Physics 13 46 20549 20556 Bibcode 2011PCCP 1320549G doi 10 1039 C1CP21959F ISSN 1463 9084 PMID 21869975 Zubarev Dmitry Yu Boldyrev Alexander I 2008 12 05 Revealing Intuitively Assessable Chemical Bonding Patterns in Organic Aromatic Molecules via Adaptive Natural Density Partitioning The Journal of Organic Chemistry 73 23 9251 9258 doi 10 1021 jo801407e ISSN 0022 3263 PMID 18980326 Sergeeva Alina P Boldyrev Alexander I 2010 09 13 Flattening a Puckered Pentasilacyclopentadienide Ring by Suppression of the Pseudo Jahn Teller Effect Organometallics 29 17 3951 3954 doi 10 1021 om1006038 ISSN 0276 7333 Pokhodnya Konstantin Olson Christopher Dai Xuliang Schulz Douglas L Boudjouk Philip Sergeeva Alina P Boldyrev Alexander I 2011 01 07 Flattening a puckered cyclohexasilane ring by suppression of the pseudo Jahn Teller effect The Journal of Chemical Physics 134 1 014105 Bibcode 2011JChPh 134a4105P doi 10 1063 1 3516179 ISSN 0021 9606 PMID 21218995 a b Ivanov Alexander S Bozhenko Konstantin V Boldyrev Alexander I 2012 08 20 On the Suppression Mechanism of the Pseudo Jahn Teller Effect in Middle E6 E P As Sb Rings of Triple Decker Sandwich Complexes Inorganic Chemistry 51 16 8868 8872 doi 10 1021 ic300786w ISSN 0020 1669 PMID 22845625 Retrieved from https en wikipedia org w index php title Hexaphosphabenzene amp oldid 1214870834, wikipedia, wiki, book, books, library,

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