Zinc hydride

Zinc hydride
IUPAC name

Zinc hydride
Identifiers
CAS number 14018-82-7 Y
PubChem 22056524
ChemSpider 10806557 N
Jmol-3D images Image 1
Properties
Molecular formula ZnH2
Molar mass 67.425 g mol-1
Exact mass 65.944796642 g mol-1
Appearance Colourless crystals
Structure
Coordination
geometry		 linear at Zn
Molecular shape linear
Dipole moment 0 D
 N (verify) (what is: Y/N?)
Except where noted otherwise, data are given for materials in their standard state (at 25 °C, 100 kPa)
Infobox references

Zinc hydride is a chemical compound of zinc and hydrogen, ZnH2, which is used as a reducing agent in organic synthesis. First reported in 1947,[1] it is a white crystalline powder when freshly made which turns grey if left at room temperature for a few days, presumably due to the decompostion to metallic zinc.[2] It can be prepared in a number of ways:[2][3]

2LiH + ZnBr2 → ZnH2 + 2LiBr
2NaH + ZnI2 → ZnH2 + 2NaI
ZnI2 + 2LiAlH4 → ZnH2 + AlH3 + 2LiI
Zn(CH3)2 + LiAlH4 → ZnH2 + LiAlH3(CH3)

It decomposes at 90 °C into the elements.[2] It is sensitive to air and moisture, and is hydrolysed slowly by water but violently by aqueous acids.[2] Older samples may be pyrophoric.[2] The solid state structure is not known but is believed to involve covalent bonding[4]

Molecular zinc hydride

Molecular zinc hydride has been studied in the vapour phase and is linear with a Zn-H bond length of 153.5 pm.[5]

References

  1. ^ A. E. Finholt, A. C. Bond, Jr., H. I. Schlesinger (1947). "Lithium Aluminum Hydride, Aluminum Hydride and Lithium Gallium Hydride, and Some of their Applications in Organic and Inorganic Chemistry". Journal of the American Chemical Society 69 (5): 1199–1203. doi:10.1021/ja01197a061. 
  2. ^ a b c d e Herrmann, Wolfgang A. (1997). Synthetic Methods of Organometallic and Inorganic Chemistry. Georg Thieme Verlag. ISBN 3131030615. 
  3. ^ Egon Wiberg, Arnold Frederick Holleman (2001) Inorganic Chemistry, Elsevier ISBN 0123526515
  4. ^ Mackay, Rosemary Ann; Henderson, W.; (2002). Introduction to Modern Inorganic Chemistry (6th ed.). CRC Press. ISBN 0748764208. 
  5. ^ Shayesteh, Alireza; Appadoo, Dominique R. T.; Gordon, Iouli E.; Bernath, Peter F.; Journal of the American Chemical Society (2004). "Vibration−Rotation Emission Spectra of Gaseous ZnH2 and ZnD2". Journal of the American Chemical Society 126 (44): 14356–14357. doi:10.1021/ja046050b. PMID 15521746.