Cadmium hydride (systematically named cadmium dihydride) is an inorganic compound with the chemical formula(CdH 2) n (also written as ([CdH 2]) n or CdH 2). It is a solid, known only as a thermally unstable, insoluble white powder.
The systematic name cadmium dihydride, a valid IUPAC name, is constructed according to the compositional nomenclature. Cadmium dihydride is also used to refer to the related molecular compound dihydridocadmium and its oligomers. Care should be taken to avoid confusing the two compounds.
Cadmium hydride is also used as a compositional IUPAC name for the compound with the chemical formula CdH.
History
In 1950 a research group led by Glenn D. Barbaras, synthesized cadmium hydride for the first time. This reaction sequence consisted of demethylation[dubious – discuss] of dimethylcadmium in diethyl ether at −78 °C, to cadmium hydride.[2]
Chemical properties
Solid cadmium hydride, on the basis of its infrared spectrum, is believed to contain hydrogen-bridge bonds.[3] Other lower metal hydrides polymerize in a similar fashion. Unless cooled below −20 °C (−4 °F), cadmium hydride rapidly decomposes to produce cadmium and hydrogen:[2]
(CdH 2) n → n Cd + nH 2
Dihydridocadmium
Dihydridocadmium is the monomeric, molecular form with the chemical formula CdH 2 (also written [CdH 2]). It is a colorless gas that does not persist undiluted. Dihydridocadmium has a low activation barrier toward autopolymerisation into the standard form of cadmium hydride and would rapidly do so in undiluted concentrations. Since the activation barrier for the reverse reaction is much greater than that of the decomposition reaction, autopolymerisation of dihydridocadmium may be considered as irreversible for most intents and purposes. It was produced by the gas phase reaction of excited cadmium atoms with dihydrogen, H2, and the structure determined high-resolution infrared emission spectra. The molecule is linear, with a bond length of 168.3 pm.[4]
Chemical properties
The two-coordinate hydridocadmium group (-CdH) in hydridocadmiums such as dihydridocadmium can accept an electron-pair donating ligand into the molecule by adduction:[3]
[CdH 2] + L → [CdH 2L]
Because of this acceptance of the electron-pair donating ligand (L), dihydridocadmium has Lewis-acidic character. Dihydridocadmium can accept two electron-pairs from ligands, as in the case of the tetrahydridocadmate(2−) anion (CdH2− 4).
The compound, Cs3CdH5, prepared by the reaction of caesium hydride, CsH, and cadmium metal powder at high temperature contains the CdH2− 4 ion, along with caesium cations, Cs+, and hydride anions, H−. The tetrahedral anion is an example of an ionic complex of CdH2. The average Cd-H bond length in CdH2− 4 is 182pm.[5]
In gaseous dihydridocadmium, the molecules form groups (trimers), being connected by van der Waals forces. The dissociation enthalpy of the dimer is estimated at 8.8 kJ mol−1.[3]
^ abBarbaras, Glenn D.; Dillard, Clyde; Finholt, A. E.; Wartik, Thomas; Wilzbach, K. E.; Schlesinger, Hermann I. (October 1951). "The Preparation of the Hydrides of Zinc, Cadmium, Beryllium, Magnesium and Lithium by the Use of Lithium Aluminum Hydride". Journal of the American Chemical Society. ACS Publications. 73 (10): 4585–4590. doi:10.1021/ja01154a025.
^ abcWang, Xuefeng; Andrews, Lester (December 2004). "Infrared Spectra of Zn and Cd Hydride Molecules and Solids". The Journal of Physical Chemistry A. ACS Publications. 108 (50): 11006–11013. Bibcode:2004JPCA..10811006W. doi:10.1021/jp046414m.
^Shayesteh, Alireza; Yu, Shanshan; Bernath, Peter F. (2005). "Gaseous HgH2, CdH2, and ZnH2". Chemistry: A European Journal. 11 (16): 4709–4712. doi:10.1002/chem.200500332. ISSN 0947-6539. PMID 15912545.
^Bortz, M.; Gutmann, M.; Yvon, K. (1999). "Synthesis and structure determination of the first ternary cadmium hydride, Cs3CdH5". Journal of Alloys and Compounds. 285 (1–2): L19–L21. doi:10.1016/S0925-8388(99)00031-6. ISSN 0925-8388.
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cadmium, hydride, systematically, named, cadmium, dihydride, inorganic, compound, with, chemical, formula, cdh2, also, written, cdh2, cdh2, solid, known, only, thermally, unstable, insoluble, white, powder, namesother, names, cadmium, hydridecadmium, dihydride. Cadmium hydride systematically named cadmium dihydride is an inorganic compound with the chemical formula CdH2 n also written as CdH2 n or CdH2 It is a solid known only as a thermally unstable insoluble white powder Cadmium hydride NamesOther names Cadmium II hydrideCadmium dihydrideIdentifiersCAS Number 72172 64 6 N3D model JSmol Interactive imageChemSpider 29331616 YInChI InChI 1S Cd 2H q 2 2 1 NKey IVRSYBKJJXDUEX UHFFFAOYSA N NInChI 1 Cd 2H q 2 2 1Key IVRSYBKJJXDUEX UHFFFAOYARSMILES H H Cd 2 PropertiesChemical formula CdH2Molar mass 113 419 g mol 1HazardsNIOSH US health exposure limits PEL Permissible 1910 1027 TWA 0 005 mg m3 as Cd 1 REL Recommended Ca 1 IDLH Immediate danger Ca 9 mg m3 as Cd 1 Related compoundsRelated compounds Mercury II hydrideExcept where otherwise noted data are given for materials in their standard state at 25 C 77 F 100 kPa N verify what is Y N Infobox references Contents 1 Nomenclature 2 History 3 Chemical properties 4 Dihydridocadmium 4 1 Chemical properties 5 ReferencesNomenclature EditThe systematic name cadmium dihydride a valid IUPAC name is constructed according to the compositional nomenclature Cadmium dihydride is also used to refer to the related molecular compound dihydridocadmium and its oligomers Care should be taken to avoid confusing the two compounds Cadmium hydride is also used as a compositional IUPAC name for the compound with the chemical formula CdH History EditIn 1950 a research group led by Glenn D Barbaras synthesized cadmium hydride for the first time This reaction sequence consisted of demethylation dubious discuss of dimethylcadmium in diethyl ether at 78 C to cadmium hydride 2 Chemical properties EditSolid cadmium hydride on the basis of its infrared spectrum is believed to contain hydrogen bridge bonds 3 Other lower metal hydrides polymerize in a similar fashion Unless cooled below 20 C 4 F cadmium hydride rapidly decomposes to produce cadmium and hydrogen 2 CdH2 n n Cd n H2Dihydridocadmium EditDihydridocadmium is the monomeric molecular form with the chemical formula CdH2 also written CdH2 It is a colorless gas that does not persist undiluted Dihydridocadmium has a low activation barrier toward autopolymerisation into the standard form of cadmium hydride and would rapidly do so in undiluted concentrations Since the activation barrier for the reverse reaction is much greater than that of the decomposition reaction autopolymerisation of dihydridocadmium may be considered as irreversible for most intents and purposes It was produced by the gas phase reaction of excited cadmium atoms with dihydrogen H2 and the structure determined high resolution infrared emission spectra The molecule is linear with a bond length of 168 3 pm 4 Chemical properties Edit The two coordinate hydridocadmium group CdH in hydridocadmiums such as dihydridocadmium can accept an electron pair donating ligand into the molecule by adduction 3 CdH2 L CdH2 L Because of this acceptance of the electron pair donating ligand L dihydridocadmium has Lewis acidic character Dihydridocadmium can accept two electron pairs from ligands as in the case of the tetrahydridocadmate 2 anion CdH2 4 The compound Cs3CdH5 prepared by the reaction of caesium hydride CsH and cadmium metal powder at high temperature contains the CdH2 4 ion along with caesium cations Cs and hydride anions H The tetrahedral anion is an example of an ionic complex of CdH2 The average Cd H bond length in CdH2 4 is 182pm 5 In gaseous dihydridocadmium the molecules form groups trimers being connected by van der Waals forces The dissociation enthalpy of the dimer is estimated at 8 8 kJ mol 1 3 References Edit a b c NIOSH Pocket Guide to Chemical Hazards 0087 National Institute for Occupational Safety and Health NIOSH a b Barbaras Glenn D Dillard Clyde Finholt A E Wartik Thomas Wilzbach K E Schlesinger Hermann I October 1951 The Preparation of the Hydrides of Zinc Cadmium Beryllium Magnesium and Lithium by the Use of Lithium Aluminum Hydride Journal of the American Chemical Society ACS Publications 73 10 4585 4590 doi 10 1021 ja01154a025 a b c Wang Xuefeng Andrews Lester December 2004 Infrared Spectra of Zn and Cd Hydride Molecules and Solids The Journal of Physical Chemistry A ACS Publications 108 50 11006 11013 Bibcode 2004JPCA 10811006W doi 10 1021 jp046414m Shayesteh Alireza Yu Shanshan Bernath Peter F 2005 Gaseous HgH2 CdH2 and ZnH2 Chemistry A European Journal 11 16 4709 4712 doi 10 1002 chem 200500332 ISSN 0947 6539 PMID 15912545 Bortz M Gutmann M Yvon K 1999 Synthesis and structure determination of the first ternary cadmium hydride Cs3CdH5 Journal of Alloys and Compounds 285 1 2 L19 L21 doi 10 1016 S0925 8388 99 00031 6 ISSN 0925 8388 This inorganic compound related article is a stub You can help Wikipedia by expanding it vte Retrieved from https en wikipedia org w index php title Cadmium hydride amp oldid 1075814340, wikipedia, wiki, book, books, library,
