fbpx
Wikipedia

Metal acetylacetonates

November 07, 2023

Metal acetylacetonates are coordination complexes derived from the acetylacetonate anion (CH
3COCHCOCH−
3) and metal ions, usually transition metals. The bidentate ligand acetylacetonate is often abbreviated acac. Typically both oxygen atoms bind to the metal to form a six-membered chelate ring. The simplest complexes have the formula M(acac)3 and M(acac)2. Mixed-ligand complexes, e.g. VO(acac)2, are also numerous. Variations of acetylacetonate have also been developed with myriad substituents in place of methyl (RCOCHCOR′−).[1] Many such complexes are soluble in organic solvents, in contrast to the related metal halides. Because of these properties, acac complexes are sometimes used as catalyst precursors and reagents. Applications include their use as NMR "shift reagents" and as catalysts for organic synthesis, and precursors to industrial hydroformylation catalysts. C
5H
7O−
2 in some cases also binds to metals through the central carbon atom; this bonding mode is more common for the third-row transition metals such as platinum(II) and iridium(III).

Synthesis edit

The usual synthesis involves treatment of a metal salt with acetylacetone, acacH:[2]

Mz+ + z Hacac ⇌ M(acac)z + z H+

Addition of base assists the removal of a proton from acetylacetone and shifts the equilibrium in favour of the complex. Both oxygen centres bind to the metal to form a six-membered chelate ring. In some cases the chelate effect is so strong that no added base is needed to form the complex. Some complexes are prepared by metathesis using Tl(acac).

Structure and bonding edit

In the majority of its complexes acac forms six-membered C3O2M chelate rings.[3] The M(acac) ring is planar with a symmetry plane bisecting the ring.

The acacM ring generally exhibits aromatic character, consistent with delocalized bonding in the monoanionic C3O2 portion. Consistent with this scenario, in some complexes, the acac ligand is susceptible to electrophilic substitution, akin to electrophilic aromatic substitution (in this equation Me = CH3):[4]

Co(O2C3Me2H)3 + 3 NO2+ → Co(O2C3Me2NO2)3 + 3 H+

In terms of electron counting, neutral bidentate O,O-bonded acac ligand is an "L-X ligand", i.e. a combination of a Lewis base (L) and a pseudohalide (X).

An exception to the classical description presented above, the bis(pyridine) adduct of chromium(II) acetylacetonate features noninnocent acac2- ligand.[5]

Classification by triad edit

Titanium triad edit

Treatment of TiCl4 with acetylacetone gives TiCl2(acac)2, a red-coloured, octahedral complex with C2 symmetry:

TiCl4 + 2 Hacac → TiCl2(acac)2 + 2 HCl

This reaction requires no base. The complex TiCl2(acac)2 is fluxional in solution, the NMR spectrum exhibiting a single methyl resonance at room temperature.[6]

Unlike Ti(IV), both Zr(IV) and Hf(IV) bind four bidentate acetylacetonates, reflecting the larger radius of these metals. Hafnium acetylacetonate and zirconium acetylacetonate adopt square antiprismatic structures.

Regarding acetylacetonates of titanium(III), Ti(acac)3 is well studied. This blue-colored compound forms from titanium trichloride and acetylacetone.[3]

Vanadium triad edit

 
A ball-and-stick model of VO(acac)2

Vanadyl acetylacetonate is a blue complex with the formula V(O)(acac)2. This complex features the vanadyl(IV) group, and many related compounds are known. The molecule is square pyramidal, with idealized C2v symmetry. The complex catalyzes epoxidation of allylic alcohols by peroxides. Vanadium(III) acetylacetonate is a dark-brown solid. Vanadium β-diketonate complexes are used as precatalysts in the commercial production of ethylene-propylene-diene elastomers (EPDM). They are often evaluated for other applications related to redox flow batteries, diabetes and enhancing the activity of insulin, and as precursors to inorganic materials by CVD.[7]

Chromium triad edit

Chromium(III) acetylacetonate, Cr(acac)3, is a typical octahedral complex containing three acac− ligands. Like most such compounds, it is highly soluble in nonpolar organic solvents. This particular complex, which has a three unpaired electrons, is used as a spin relaxation agent to improve the sensitivity in quantitative carbon-13 NMR spectroscopy.[8] Chromium(II) acetylacetonate is a highly oxygen-sensitive, light brown compound. The complex adopts a square planar structure, weakly associated into stacks in the solid state. It is isomorphous with Pd(acac)2 and Cu(acac)2.[9]

Manganese triad edit

 
Ball-and-stick model of Δ-Mn(acac)3, with Jahn–Teller tetragonal elongation

Mn(acac)3 has been prepared by the comproportionation of the manganese(II) compound Mn(acac)2 with potassium permanganate in the presence of additional acetylacetone.[10] Alternatively the direct reaction of acetylacetone with potassium permanganate.[11] In terms of electronic structure, Mn(acac)3 is high spin. Its distorted octahedral structure reflects geometric distortions due to the Jahn–Teller effect. The two most common structures for this complex include one with tetragonal elongation and one with tetragonal compression. For the elongation, two Mn–O bonds are 2.12 Å while the other four are 1.93 Å. For the compression, two Mn–O bonds are 1.95 Å and the other four are 2.00 Å. The effects of the tetragonal elongation are noticeably more significant than the effects of the tetragonal compression.[12]

 

In organic chemistry, Mn(acac)3 has been used as a one-electron oxidant for coupling phenols.[13]

The electron transfer rates for Mn(acac)3 have been evaluated.[14]-

Iron triad edit

Iron(III) acetylacetonate, Fe(acac)3, is a red high-spin complex that is highly soluble in organic solvents. It is a high-spin complex with five unpaired electrons. It has occasionally been investigated as a catalyst precursor.[15] Fe(acac)3 has been partially resolved into its Δ and Λ isomers.[16] The ferrous complex Fe(acac)2 is oligomeric.

Like iron, Ru(III) forms a stable tris(acetylacetonate). Reduction of this Ru(III) derivative in the presence of other ligands affords mixed ligand complexes, e.g. Ru(acac)2(alkene)2.[17]

Cobalt triad edit

 
Rh(acac)(CO)2 showing the "stacking" of the individual planar units through Rh---Rh interactions.

Tris(acetylacetonato)cobalt(III), Co(acac)3, is low-spin, diamagnetic complex. Like other compounds of the type M(acac)3, this complex is chiral (has a non-superimposable mirror image).[16]

 

The synthesis of Co(acac)3 involves the use of an oxidant since the cobalt precursors are divalent:

2 CoCO3 + 6 Hacac + H2O2 → 2 Co(acac)3 + 4 H2O + 2 CO2

The complex "Co(acac)2", like the nickel complex with analogous stoichiometry, is typically isolated with two additional ligands, i.e. octahedral Co(acac)2L2. The anhydrous form exists as the tetramer [Co(acac)2]4. Like the trimeric nickel complex, this tetramer shows ferromagnetic interactions at low temperatures.[18]

Ir(acac)3 and Rh(acac)3 are known. A second linkage isomer of the iridium complex is known, trans-Ir(acac)2(CH(COMe)2)(H2O). This C-bonded derivative is a precursor to homogeneous catalysts for C–H activation and related chemistries.[19][20][21][22]

Two well-studied acetylacetonates of rhodium(I) and iridium(I) are Rh(acac)(CO)2 and Ir(acac)(CO)2. These complexes are square-planar, with C2v symmetry.

Nickel triad edit

 
Stick model of [Ni(acac)2]3

Nickel(II) bis(acetylacetonate) exists as the trimetallic complex [Ni(acac)2]3. Bulky beta-diketonates give red, monomeric, square-planar complexes.[23] Nickel(II) bis(acetylacetonate) reacts with water to give the octahedral[24] adduct [Ni(acac)2(H2O)2], a chalky green solid.

In contrast to the complicated magnetism and structures of Ni(acac)2, platinum(II) bis(acetylacetonate) and palladium(II) bis(acetylacetonate) are diamagnetic monometallic species.

Copper triad edit

Cu(acac)2 is prepared by treating acetylacetone with aqueous Cu(NH
3)2+
4. It is available commercially, catalyzes coupling and carbene transfer reactions.

 

Unlike the copper(II) derivative, copper(I) acetylacetonate is an air-sensitive oligomeric species. It is employed to catalyze Michael additions.[25]

Zinc triad edit

The monoaquo complex Zn(acac)2H2O (m.p. 138–140 °C) is pentacoordinate, adopting a square pyramidal structure.[26] The complex is of some use in organic synthesis.[27] Dehydration of this species gives the hygroscopic anhydrous derivative (m.p. 127 °C).[28] This more volatile derivative has been used as a precursor to films of ZnO.

Acetylacetonates of the other elements edit

Colourless, diamagnetic Al(acac)3 is structurally similar to other tris complexes, e.g. [Fe(acac)3]. The trisacetylacetonates of the lanthanides often adopt coordination numbers above 8.

Variants of acac edit

Many variants of acetylacetonates are well developed. Hexafluoroacetylacetonates and trifluoroacetylacetonates form complexes that are often structurally related to regular acetylacetonates, but are more Lewis acidic and more volatile. The complex Eufod, Eu(OCC(CH3)3CHCOC3F7)3, features an elaborate partially fluorinated ligand. This complex is a Lewis acid, forming adducts with a variety of hard bases.

One or both oxygen centers in acetylacetonate can be replaced by RN groups, giving rise to Nacac and Nacnac ligands.

C-bonded acetylacetonates edit

C
5H
7O−
2 in some cases also binds to metals through the central carbon atom (C3); this bonding mode is more common for the third-row transition metals such as platinum(II) and iridium(III). The complexes Ir(acac)3 and corresponding Lewis-base adducts Ir(acac)3L (L = an amine) contain one carbon-bonded acac ligand. The IR spectra of O-bonded acetylacetonates are characterized by relatively low-energy νCO bands of 1535 cm−1, whereas in carbon-bonded acetylacetonates, the carbonyl vibration occurs closer to the normal range for ketonic C=O, i.e. 1655 cm−1.

References edit

  1. ^ Albrecht, M.; Schmid, S.; De Groot, M.; Weis, P.; Fröhlich, R. (2003). "Self-assembly of an Unpolar Enantiomerically Pure Helicate-type Metalla-cryptand". Chem. Comm. 2003 (20): 2526–2527. doi:10.1039/b309026d. PMID 14594263.
  2. ^ R. C. Mehrotra; R. Bohra; D. P. Gaur (1978). Metal ß-Diketones and Allied Derivatives. Academic Press. ISBN 0-12-488150-5.
  3. ^ a b Arslan, Evrim; Lalancette, Roger A.; Bernal, Ivan (2017). "An Historic and Scientific Study of the Properties of Metal(III) Tris-acetylacetonates". Structural Chemistry. 28: 201–212. doi:10.1007/s11224-016-0864-0. S2CID 99668641.
  4. ^ Shalhoub, George M. (1980). "Co(acac)3 Synthesis, Reactions, and Spectra: An Experiment for General Chemistry". Journal of Chemical Education. 57 (7): 525. Bibcode:1980JChEd..57..525S. doi:10.1021/ed057p525.
  5. ^ Vinum, Morten Gotthold; Voigt, Laura; Hansen, Steen H.; Bell, Colby; Clark, Kensha Marie; Larsen, René Wugt; Pedersen, Kasper S. (2020). "Ligand field-actuated redox-activity of acetylacetonate". Chemical Science. 11 (31): 8267–8272. doi:10.1039/d0sc01836h. PMC 8163028. PMID 34094180.
  6. ^ Wilkie, C. A.; Lin, G.; Haworth, D. T. (1979). "Cis ‐[Dihalobis(2,4‐Pentaedionato)Titanium(IV)] Complexes". Inorganic Syntheses. pp. 145–148. doi:10.1002/9780470132500.ch33. ISBN 978-0-470-13250-0. {{cite book}}: |journal= ignored (help)
  7. ^ V. D. Makhaev; L. A. Petrova (2017). "Mechanochemical synthesis of vanadium(III) β-diketonates". Zhurnal Obshchei Khimii (Russian Journal of General Chemistry). 87 (6): 1105–1109. doi:10.1134/s1070363217060019. S2CID 103887631.
  8. ^ Caytan, Elsa; Remaud, Gerald S.; Tenailleau, Eve; Akoka, Serge (2007). "Precise and accurate quantitative 13C NMR with reduced experimental time". Talanta. 71 (3): 1016–1021. doi:10.1016/j.talanta.2006.05.075. PMID 19071407.
  9. ^ Cotton, F. A.; Rice, C. E.; Rice, G. W. (1977). "The Crystal and Molecular Structures of Bis(2,4-pentanedionato)chromium". Inorg. Chim. Acta. 24: 231–234. doi:10.1016/S0020-1693(00)93880-5.
  10. ^ Charles, R. G. (1963). "Acetylacetonato manganese(III)". Inorganic Syntheses Vol 7. pp. 183–184. doi:10.1002/9780470132388.ch49. ISBN 978-0-470-13238-8. {{cite book}}: |journal= ignored (help)
  11. ^ Girolami, G.; Rauchfuss, T.; Angelici, R. Synthesis and Technique in Inorganic Chemistry, 3rd ed.; University Science Books: Sausalito, CA, 1999; pp. 85-92. ISBN 0-935702-48-2
  12. ^ Cotton, F. Albert; Wilkinson, Geoffrey; Murillo, Carlos A.; Bochmann, Manfred (1999), Advanced Inorganic Chemistry (6th ed.), New York: Wiley-Interscience, ISBN 0-471-19957-5
  13. ^ Snider, B. B. (2001). "Manganese(III) Acetylacetonate". In Paquette, L. (ed.). Encyclopedia of Reagents for Organic Synthesis. New York, NY: J. Wiley & Sons. doi:10.1002/047084289X.rm022. ISBN 0-471-93623-5.
  14. ^ Fawcett, W.; Opallo, M. (1992). "Kinetic parameters for heterogeneous electron transfer to tris(acetylacetonato)manganese(III) and tris(acetylacetonato)iron(III) in aprotic solvents". Journal of Electroanalytical Chemistry. 331 (1–2): 815–830. doi:10.1016/0022-0728(92)85008-Q.
  15. ^ Richert, S. A.; Tsang, P. K. S.; Sawyer, D. T. (1989). "Ligand-centered redox processes for manganese, iron and cobalt, MnL3, FeL3, and CoL3, complexes (L = acetylacetonate, 8-quinolinate, picolinate, 2,2′-bipyridyl, 1,10-phenanthroline) and for their tetrakis(2,6-dichlorophenyl)porphinato complexes [M(Por)]". Inorg. Chem. 28 (12): 2471–2475. doi:10.1021/ic00311a044.
  16. ^ a b Lennartson, Anders (2011). "Optical resolution and racemisation of [Fe(acac)3]". Inorg. Chim. Acta. 365: 451–453. doi:10.1016/j.ica.2010.07.066.
  17. ^ Bennett, M. A.; Heath, G. A.; Hockless, D. C. R.; Kovacik, I.; Willis, A. C. (1998). "Alkene Complexes of Divalent and Trivalent Ruthenium Stabilized by Chelation. Dependence of Coordinated Alkene Orientation on Metal Oxidation State". J. Am. Chem. Soc. 120 (5): 932–941. doi:10.1021/ja973282k.
  18. ^ Vreshch, V. D.; H. Zhang, J.-H. Yang; Filatov, A. S.; Dikarev, E. V. (2010). "Monomeric Square-Planar Cobalt(II) Acetylacetonate: Mystery or Mistake?". Inorg. Chem. 49 (18): 8430–8434. doi:10.1021/ic100963r. PMID 20795642.
  19. ^ Bennett, M. A.; Mitchell, T. R. B. (1976). "γ-Carbon-bonded 2,4-pentanedionato complexes of trivalent iridium". Inorg. Chem. 15 (11): 2936–8. doi:10.1021/ic50165a079.
  20. ^ Bhalla, G.; Oxgaard, J.; Goddard, W. A.; Periana, Roy A. (2005). "Hydrovinylation of Olefins Catalyzed by an Iridium Complex via CH Activation" (PDF). Organometallics. 24 (23): 5499–5502. doi:10.1021/om050614i.
  21. ^ Wong-Foy, A. G.; Bhalla, G.; Liu, X. Y.; Periana, R.A. (2003). "Alkane C–H Activation and Catalysis by an O-Donor Ligated Iridium Complex". J. Am. Chem. Soc. 125 (47): 14292–14293. doi:10.1021/ja037849a. PMID 14624574.
  22. ^ Tenn, William J.; Young, Kenneth J. H.; Bhalla, Gaurav; Oxgaard, Jonas; Goddard, William A.; Periana, Roy A. (2005). "CH Activation with an O-Donor Iridium-Methoxo Complex" (PDF). J. Am. Chem. Soc. 127 (41): 14172–14173. doi:10.1021/ja051497l. PMID 16218597.
  23. ^ Döhring, A.; Goddard, R.; Jolly, P. W.; Krüger, C.; Polyakov, V. R. (2007). "Monomer–Trimer Isomerism in 3-Substituted Pentane-2,4-dione Derivatives of Nickel(II)". Inorg. Chem. 36 (2): 177–183. doi:10.1021/ic960441c.
  24. ^ Williams, Paul; Jones, Anthony; Bickley, Jamie; Steiner, Alexander; Davies, Hywel; Leedham, Timothy; Impey, Susan; Garcia, Joanne; Allen, Stephen; Rougier, Aline; Blyr, Alexandra (2 August 2001). "Synthesis and crystal structures of dimethylaminoethanol adducts of Ni(ii) acetate and Ni(ii) acetylacetonate. Precursors for the sol–gel deposition of electrochromic nickel oxide thin films". Journal of Materials Chemistry. Royal Society of Chemistry. 11 (9): 2329–2334. doi:10.1039/B103288G. (subscription required)
  25. ^ Parish, E. J.; Li, S. (2004). "Copper(I) Acetylacetonate". In Paquette, L. (ed.). Encyclopedia of Reagents for Organic Synthesis. New York, NY: J. Wiley & Sons. doi:10.1002/047084289X.rc203. ISBN 0-471-93623-5.
  26. ^ Montgomery, H.; Lingafelter, E. C. (1963). "The crystal structure of monoaquobisacetylacetonatozinc". Acta Crystallographica. 16 (8): 748–752. doi:10.1107/S0365110X6300195X.
  27. ^ Barta, N. (2004). "Bis(acetylacetonato)zinc(II)". In Paquette, L. (ed.). Encyclopedia of Reagents for Organic Synthesis. New York, NY: J. Wiley & Sons. doi:10.1002/047084289X.rb097. ISBN 0-471-93623-5.
  28. ^ Rudolph, G.; Henry, M. C. (1967). "Bis(2,4-Pentanedionato)zinc (Zinc Acetylacetonate)". Inorg. Synth. 10: 74–77. doi:10.1002/9780470132418.ch14.
  29. ^ Koiwa, Tomohiro; Masuda, Yuki; Shono, Junpei; Kawamoto, Yuji; Hoshino, Yoshimasa; Hashimoto, Takeshi; Natarajan, Karuppannan; Shimizu, Kunio (2004). "Synthesis, Characterization, and Detailed Electrochemistry of Binuclear Ruthenium(III) Complexes Bridged by Bisacetylacetonate. Crystal and Molecular Structures of [{Ru(acac)2}2(tae)] (Acac = 2,4-Pentanedionate Ion, tae = 1,1,2,2-Tetraacetylethanate Dianion)". Inorganic Chemistry. 43 (20): 6215–6223. doi:10.1021/ic030216c. PMID 15446866.
  30. ^ Basato, Marino; Caneva, Elisabetta; Tubaro, Cristina; Veronese, Augusto Cesare (2009). "Coordinating Properties of the Anionic Ligand (MeCO)2C(−)C(X)Me (X=O or NH) Toward Transition Metal(II) Centers". Inorganica Chimica Acta. 362 (8): 2551–2555. doi:10.1016/j.ica.2008.11.017.
  31. ^ Murtha, D. P.; Lintvedt, Richard L. (1970). "Bis(1,3,5-triketonato)dicopper(II)chelates. Ferromagnetic and antiferromagnetic exchange between copper(II) ions". Inorganic Chemistry. 9 (6): 1532–1535. doi:10.1021/ic50088a046.

November 07, 2023
metal, acetylacetonates, coordination, complexes, derived, from, acetylacetonate, anion, cochcoch, metal, ions, usually, transition, metals, bidentate, ligand, acetylacetonate, often, abbreviated, acac, typically, both, oxygen, atoms, bind, metal, form, member. Metal acetylacetonates are coordination complexes derived from the acetylacetonate anion CH3 COCHCOCH 3 and metal ions usually transition metals The bidentate ligand acetylacetonate is often abbreviated acac Typically both oxygen atoms bind to the metal to form a six membered chelate ring The simplest complexes have the formula M acac 3 and M acac 2 Mixed ligand complexes e g VO acac 2 are also numerous Variations of acetylacetonate have also been developed with myriad substituents in place of methyl RCOCHCOR 1 Many such complexes are soluble in organic solvents in contrast to the related metal halides Because of these properties acac complexes are sometimes used as catalyst precursors and reagents Applications include their use as NMR shift reagents and as catalysts for organic synthesis and precursors to industrial hydroformylation catalysts C5 H7 O 2 in some cases also binds to metals through the central carbon atom this bonding mode is more common for the third row transition metals such as platinum II and iridium III Contents 1 Synthesis 2 Structure and bonding 3 Classification by triad 3 1 Titanium triad 3 2 Vanadium triad 3 3 Chromium triad 3 4 Manganese triad 3 5 Iron triad 3 6 Cobalt triad 3 7 Nickel triad 3 8 Copper triad 3 9 Zinc triad 4 Acetylacetonates of the other elements 5 Variants of acac 6 C bonded acetylacetonates 7 ReferencesSynthesis editThe usual synthesis involves treatment of a metal salt with acetylacetone acacH 2 Mz z Hacac M acac z z H Addition of base assists the removal of a proton from acetylacetone and shifts the equilibrium in favour of the complex Both oxygen centres bind to the metal to form a six membered chelate ring In some cases the chelate effect is so strong that no added base is needed to form the complex Some complexes are prepared by metathesis using Tl acac Structure and bonding editIn the majority of its complexes acac forms six membered C3O2M chelate rings 3 The M acac ring is planar with a symmetry plane bisecting the ring The acacM ring generally exhibits aromatic character consistent with delocalized bonding in the monoanionic C3O2 portion Consistent with this scenario in some complexes the acac ligand is susceptible to electrophilic substitution akin to electrophilic aromatic substitution in this equation Me CH3 4 Co O2C3Me2H 3 3 NO2 Co O2C3Me2NO2 3 3 H In terms of electron counting neutral bidentate O O bonded acac ligand is an L X ligand i e a combination of a Lewis base L and a pseudohalide X An exception to the classical description presented above the bis pyridine adduct of chromium II acetylacetonate features noninnocent acac2 ligand 5 Classification by triad editTitanium triad edit Treatment of TiCl4 with acetylacetone gives TiCl2 acac 2 a red coloured octahedral complex with C2 symmetry TiCl4 2 Hacac TiCl2 acac 2 2 HClThis reaction requires no base The complex TiCl2 acac 2 is fluxional in solution the NMR spectrum exhibiting a single methyl resonance at room temperature 6 Unlike Ti IV both Zr IV and Hf IV bind four bidentate acetylacetonates reflecting the larger radius of these metals Hafnium acetylacetonate and zirconium acetylacetonate adopt square antiprismatic structures Regarding acetylacetonates of titanium III Ti acac 3 is well studied This blue colored compound forms from titanium trichloride and acetylacetone 3 Vanadium triad edit nbsp A ball and stick model of VO acac 2Vanadyl acetylacetonate is a blue complex with the formula V O acac 2 This complex features the vanadyl IV group and many related compounds are known The molecule is square pyramidal with idealized C2v symmetry The complex catalyzes epoxidation of allylic alcohols by peroxides Vanadium III acetylacetonate is a dark brown solid Vanadium b diketonate complexes are used as precatalysts in the commercial production of ethylene propylene diene elastomers EPDM They are often evaluated for other applications related to redox flow batteries diabetes and enhancing the activity of insulin and as precursors to inorganic materials by CVD 7 Chromium triad edit Chromium III acetylacetonate Cr acac 3 is a typical octahedral complex containing three acac ligands Like most such compounds it is highly soluble in nonpolar organic solvents This particular complex which has a three unpaired electrons is used as a spin relaxation agent to improve the sensitivity in quantitative carbon 13 NMR spectroscopy 8 Chromium II acetylacetonate is a highly oxygen sensitive light brown compound The complex adopts a square planar structure weakly associated into stacks in the solid state It is isomorphous with Pd acac 2 and Cu acac 2 9 Manganese triad edit nbsp Ball and stick model of D Mn acac 3 with Jahn Teller tetragonal elongationMn acac 3 has been prepared by the comproportionation of the manganese II compound Mn acac 2 with potassium permanganate in the presence of additional acetylacetone 10 Alternatively the direct reaction of acetylacetone with potassium permanganate 11 In terms of electronic structure Mn acac 3 is high spin Its distorted octahedral structure reflects geometric distortions due to the Jahn Teller effect The two most common structures for this complex include one with tetragonal elongation and one with tetragonal compression For the elongation two Mn O bonds are 2 12 A while the other four are 1 93 A For the compression two Mn O bonds are 1 95 A and the other four are 2 00 A The effects of the tetragonal elongation are noticeably more significant than the effects of the tetragonal compression 12 nbsp In organic chemistry Mn acac 3 has been used as a one electron oxidant for coupling phenols 13 The electron transfer rates for Mn acac 3 have been evaluated 14 Iron triad edit Iron III acetylacetonate Fe acac 3 is a red high spin complex that is highly soluble in organic solvents It is a high spin complex with five unpaired electrons It has occasionally been investigated as a catalyst precursor 15 Fe acac 3 has been partially resolved into its D and L isomers 16 The ferrous complex Fe acac 2 is oligomeric Like iron Ru III forms a stable tris acetylacetonate Reduction of this Ru III derivative in the presence of other ligands affords mixed ligand complexes e g Ru acac 2 alkene 2 17 Cobalt triad edit nbsp Rh acac CO 2 showing the stacking of the individual planar units through Rh Rh interactions Tris acetylacetonato cobalt III Co acac 3 is low spin diamagnetic complex Like other compounds of the type M acac 3 this complex is chiral has a non superimposable mirror image 16 nbsp The synthesis of Co acac 3 involves the use of an oxidant since the cobalt precursors are divalent 2 CoCO3 6 Hacac H2O2 2 Co acac 3 4 H2O 2 CO2The complex Co acac 2 like the nickel complex with analogous stoichiometry is typically isolated with two additional ligands i e octahedral Co acac 2L2 The anhydrous form exists as the tetramer Co acac 2 4 Like the trimeric nickel complex this tetramer shows ferromagnetic interactions at low temperatures 18 Ir acac 3 and Rh acac 3 are known A second linkage isomer of the iridium complex is known trans Ir acac 2 CH COMe 2 H2O This C bonded derivative is a precursor to homogeneous catalysts for C H activation and related chemistries 19 20 21 22 Two well studied acetylacetonates of rhodium I and iridium I are Rh acac CO 2 and Ir acac CO 2 These complexes are square planar with C2v symmetry Nickel triad edit nbsp Stick model of Ni acac 2 3Nickel II bis acetylacetonate exists as the trimetallic complex Ni acac 2 3 Bulky beta diketonates give red monomeric square planar complexes 23 Nickel II bis acetylacetonate reacts with water to give the octahedral 24 adduct Ni acac 2 H2O 2 a chalky green solid In contrast to the complicated magnetism and structures of Ni acac 2 platinum II bis acetylacetonate and palladium II bis acetylacetonate are diamagnetic monometallic species Copper triad edit Cu acac 2 is prepared by treating acetylacetone with aqueous Cu NH3 2 4 It is available commercially catalyzes coupling and carbene transfer reactions nbsp Unlike the copper II derivative copper I acetylacetonate is an air sensitive oligomeric species It is employed to catalyze Michael additions 25 Zinc triad edit The monoaquo complex Zn acac 2H2O m p 138 140 C is pentacoordinate adopting a square pyramidal structure 26 The complex is of some use in organic synthesis 27 Dehydration of this species gives the hygroscopic anhydrous derivative m p 127 C 28 This more volatile derivative has been used as a precursor to films of ZnO Acetylacetonates of the other elements editColourless diamagnetic Al acac 3 is structurally similar to other tris complexes e g Fe acac 3 The trisacetylacetonates of the lanthanides often adopt coordination numbers above 8 Variants of acac editMany variants of acetylacetonates are well developed Hexafluoroacetylacetonates and trifluoroacetylacetonates form complexes that are often structurally related to regular acetylacetonates but are more Lewis acidic and more volatile The complex Eufod Eu OCC CH3 3CHCOC3F7 3 features an elaborate partially fluorinated ligand This complex is a Lewis acid forming adducts with a variety of hard bases One or both oxygen centers in acetylacetonate can be replaced by RN groups giving rise to Nacac and Nacnac ligands nbsp hexafluoroacetylacetone nbsp trifluoroacetylacetone nbsp Tautomers and complexation of Nacnac nbsp The NMR shift reagent Eufod nbsp Tetraacetylethane which forms bimetallic complexes 29 nbsp Triacetylmethane 30 nbsp 2 4 6 Heptanetrione a binucleating ligand 31 C bonded acetylacetonates editC5 H7 O 2 in some cases also binds to metals through the central carbon atom C3 this bonding mode is more common for the third row transition metals such as platinum II and iridium III The complexes Ir acac 3 and corresponding Lewis base adducts Ir acac 3L L an amine contain one carbon bonded acac ligand The IR spectra of O bonded acetylacetonates are characterized by relatively low energy nCO bands of 1535 cm 1 whereas in carbon bonded acetylacetonates the carbonyl vibration occurs closer to the normal range for ketonic C O i e 1655 cm 1 References edit Albrecht M Schmid S De Groot M Weis P Frohlich R 2003 Self assembly of an Unpolar Enantiomerically Pure Helicate type Metalla cryptand Chem Comm 2003 20 2526 2527 doi 10 1039 b309026d PMID 14594263 R C Mehrotra R Bohra D P Gaur 1978 Metal ss Diketones and Allied Derivatives Academic Press ISBN 0 12 488150 5 a b Arslan Evrim Lalancette Roger A Bernal Ivan 2017 An Historic and Scientific Study of the Properties of Metal III Tris acetylacetonates Structural Chemistry 28 201 212 doi 10 1007 s11224 016 0864 0 S2CID 99668641 Shalhoub George M 1980 Co acac 3 Synthesis Reactions and Spectra An Experiment for General Chemistry Journal of Chemical Education 57 7 525 Bibcode 1980JChEd 57 525S doi 10 1021 ed057p525 Vinum Morten Gotthold Voigt Laura Hansen Steen H Bell Colby Clark Kensha Marie Larsen Rene Wugt Pedersen Kasper S 2020 Ligand field actuated redox activity of acetylacetonate Chemical Science 11 31 8267 8272 doi 10 1039 d0sc01836h PMC 8163028 PMID 34094180 Wilkie C A Lin G Haworth D T 1979 Cis Dihalobis 2 4 Pentaedionato Titanium IV Complexes Inorganic Syntheses pp 145 148 doi 10 1002 9780470132500 ch33 ISBN 978 0 470 13250 0 a href Template Cite book html title Template Cite book cite book a journal ignored help V D Makhaev L A Petrova 2017 Mechanochemical synthesis of vanadium III b diketonates Zhurnal Obshchei Khimii Russian Journal of General Chemistry 87 6 1105 1109 doi 10 1134 s1070363217060019 S2CID 103887631 Caytan Elsa Remaud Gerald S Tenailleau Eve Akoka Serge 2007 Precise and accurate quantitative 13C NMR with reduced experimental time Talanta 71 3 1016 1021 doi 10 1016 j talanta 2006 05 075 PMID 19071407 Cotton F A Rice C E Rice G W 1977 The Crystal and Molecular Structures of Bis 2 4 pentanedionato chromium Inorg Chim Acta 24 231 234 doi 10 1016 S0020 1693 00 93880 5 Charles R G 1963 Acetylacetonato manganese III Inorganic Syntheses Vol 7 pp 183 184 doi 10 1002 9780470132388 ch49 ISBN 978 0 470 13238 8 a href Template Cite book html title Template Cite book cite book a journal ignored help Girolami G Rauchfuss T Angelici R Synthesis and Technique in Inorganic Chemistry 3rd ed University Science Books Sausalito CA 1999 pp 85 92 ISBN 0 935702 48 2 Cotton F Albert Wilkinson Geoffrey Murillo Carlos A Bochmann Manfred 1999 Advanced Inorganic Chemistry 6th ed New York Wiley Interscience ISBN 0 471 19957 5 Snider B B 2001 Manganese III Acetylacetonate In Paquette L ed Encyclopedia of Reagents for Organic Synthesis New York NY J Wiley amp Sons doi 10 1002 047084289X rm022 ISBN 0 471 93623 5 Fawcett W Opallo M 1992 Kinetic parameters for heterogeneous electron transfer to tris acetylacetonato manganese III and tris acetylacetonato iron III in aprotic solvents Journal of Electroanalytical Chemistry 331 1 2 815 830 doi 10 1016 0022 0728 92 85008 Q Richert S A Tsang P K S Sawyer D T 1989 Ligand centered redox processes for manganese iron and cobalt MnL3 FeL3 and CoL3 complexes L acetylacetonate 8 quinolinate picolinate 2 2 bipyridyl 1 10 phenanthroline and for their tetrakis 2 6 dichlorophenyl porphinato complexes M Por Inorg Chem 28 12 2471 2475 doi 10 1021 ic00311a044 a b Lennartson Anders 2011 Optical resolution and racemisation of Fe acac 3 Inorg Chim Acta 365 451 453 doi 10 1016 j ica 2010 07 066 Bennett M A Heath G A Hockless D C R Kovacik I Willis A C 1998 Alkene Complexes of Divalent and Trivalent Ruthenium Stabilized by Chelation Dependence of Coordinated Alkene Orientation on Metal Oxidation State J Am Chem Soc 120 5 932 941 doi 10 1021 ja973282k Vreshch V D H Zhang J H Yang Filatov A S Dikarev E V 2010 Monomeric Square Planar Cobalt II Acetylacetonate Mystery or Mistake Inorg Chem 49 18 8430 8434 doi 10 1021 ic100963r PMID 20795642 Bennett M A Mitchell T R B 1976 g Carbon bonded 2 4 pentanedionato complexes of trivalent iridium Inorg Chem 15 11 2936 8 doi 10 1021 ic50165a079 Bhalla G Oxgaard J Goddard W A Periana Roy A 2005 Hydrovinylation of Olefins Catalyzed by an Iridium Complex via CH Activation PDF Organometallics 24 23 5499 5502 doi 10 1021 om050614i Wong Foy A G Bhalla G Liu X Y Periana R A 2003 Alkane C H Activation and Catalysis by an O Donor Ligated Iridium Complex J Am Chem Soc 125 47 14292 14293 doi 10 1021 ja037849a PMID 14624574 Tenn William J Young Kenneth J H Bhalla Gaurav Oxgaard Jonas Goddard William A Periana Roy A 2005 CH Activation with an O Donor Iridium Methoxo Complex PDF J Am Chem Soc 127 41 14172 14173 doi 10 1021 ja051497l PMID 16218597 Dohring A Goddard R Jolly P W Kruger C Polyakov V R 2007 Monomer Trimer Isomerism in 3 Substituted Pentane 2 4 dione Derivatives of Nickel II Inorg Chem 36 2 177 183 doi 10 1021 ic960441c Williams Paul Jones Anthony Bickley Jamie Steiner Alexander Davies Hywel Leedham Timothy Impey Susan Garcia Joanne Allen Stephen Rougier Aline Blyr Alexandra 2 August 2001 Synthesis and crystal structures of dimethylaminoethanol adducts of Ni ii acetate and Ni ii acetylacetonate Precursors for the sol gel deposition of electrochromic nickel oxide thin films Journal of Materials Chemistry Royal Society of Chemistry 11 9 2329 2334 doi 10 1039 B103288G subscription required Parish E J Li S 2004 Copper I Acetylacetonate In Paquette L ed Encyclopedia of Reagents for Organic Synthesis New York NY J Wiley amp Sons doi 10 1002 047084289X rc203 ISBN 0 471 93623 5 Montgomery H Lingafelter E C 1963 The crystal structure of monoaquobisacetylacetonatozinc Acta Crystallographica 16 8 748 752 doi 10 1107 S0365110X6300195X Barta N 2004 Bis acetylacetonato zinc II In Paquette L ed Encyclopedia of Reagents for Organic Synthesis New York NY J Wiley amp Sons doi 10 1002 047084289X rb097 ISBN 0 471 93623 5 Rudolph G Henry M C 1967 Bis 2 4 Pentanedionato zinc Zinc Acetylacetonate Inorg Synth 10 74 77 doi 10 1002 9780470132418 ch14 Koiwa Tomohiro Masuda Yuki Shono Junpei Kawamoto Yuji Hoshino Yoshimasa Hashimoto Takeshi Natarajan Karuppannan Shimizu Kunio 2004 Synthesis Characterization and Detailed Electrochemistry of Binuclear Ruthenium III Complexes Bridged by Bisacetylacetonate Crystal and Molecular Structures of Ru acac 2 2 tae Acac 2 4 Pentanedionate Ion tae 1 1 2 2 Tetraacetylethanate Dianion Inorganic Chemistry 43 20 6215 6223 doi 10 1021 ic030216c PMID 15446866 Basato Marino Caneva Elisabetta Tubaro Cristina Veronese Augusto Cesare 2009 Coordinating Properties of the Anionic Ligand MeCO 2C C X Me X O or NH Toward Transition Metal II Centers Inorganica Chimica Acta 362 8 2551 2555 doi 10 1016 j ica 2008 11 017 Murtha D P Lintvedt Richard L 1970 Bis 1 3 5 triketonato dicopper II chelates Ferromagnetic and antiferromagnetic exchange between copper II ions Inorganic Chemistry 9 6 1532 1535 doi 10 1021 ic50088a046 Retrieved from https en wikipedia org w index php title Metal acetylacetonates amp oldid 1183390723, wikipedia, wiki, book, books, library,

article

, read, download, free, free download, mp3, video, mp4, 3gp, jpg, jpeg, gif, png, picture, music, song, movie, book, game, games.