Preparation and properties of gallaborane, GaBH6: Structure of the gaseous molecule H2Ga(mu-H)(2)BH2 as determined by vibrational, electron diffraction, and ab initio studies, and structure of the crystalline solid at 110 K as determined by X-ray diffraction

A J Downs, T M Greene, E Johnsen, P T Brain, C A Morrison, S Parsons, C R Pulham, K Aarset, I M Mills, E M Page, D A Rice

Research output: Contribution to journalArticlepeer-review

Abstract

Gallaborane (GaBH6, 1), synthesized by the metathesis of LiBH4 with [H2GaCl](n) at ca. 250 K, has been characterized by chemical analysis and by its IR and H-1 and B-11 NMR spectra. The IR spectrum of the vapor at low pressure implies the presence of only one species, viz. H2Ga(mu -H)(2)BH2, with a diborane-like structure conforming to C-2v symmetry. The structure of this molecule has been determined by gas-phase electron diffraction (GED) measurements afforced by the results of ab initio molecular orbital calculations. Hence the principal distances (r(alpha) in Angstrom) and angles (angle (alpha) in deg) are as follows: r(Ga . . .B), 2.197(3); r(Ga-H-t), 1.555(6); r-(Ga-H-b), 1.800(6); r(B-H-t), 1.189(7); r(B-H-b), 1.286(7); angleH(b)-Ga-H-b, 71.6(4); and angleH(b)-B-H-b, 110.0(5) (t = terminal, b = bridging). Aggregation of the molecules occurs in the condensed phases. X-ray crystallographic studies of a single crystal at 110 K reveal a polymeric network with helical chains made up of alternating pseudotetrahedral GaH4 and BH4 units linked through single hydrogen bridges; the average Ga . . .B distance is now 2.473(7) Angstrom. The compound decomposes in the condensed phases at temperatures exceeding ca. 240 K with the formation of elemental Ga and H-2 and B2H6. The reactions with NH3, Me3N, and Me3P are also described.

Original languageEnglish
Pages (from-to)3484-3497
Number of pages14
JournalInorganic Chemistry
Volume40
Issue number14
DOIs
Publication statusPublished - 2 Jul 2001

Fingerprint

Dive into the research topics of 'Preparation and properties of gallaborane, GaBH6: Structure of the gaseous molecule H2Ga(mu-H)(2)BH2 as determined by vibrational, electron diffraction, and ab initio studies, and structure of the crystalline solid at 110 K as determined by X-ray diffraction'. Together they form a unique fingerprint.

Cite this