On the assignment of SiH and SiD stretching frequencies: A reanalysis of the ν7 bands of Si2H6 and Si2D6 and a harmonic local mode force field for disilane
✍ Scribed by D.C. McKean
- Publisher
- Elsevier Science
- Year
- 1992
- Tongue
- English
- Weight
- 592 KB
- Volume
- 48
- Category
- Article
- ISSN
- 1386-1425
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✦ Synopsis
AImtract--Assignments of v(SiH) and v(SiD) modes in SiHX3, SiH2X 2 and SiH3X compounds are surveyed. With a few exceptions, v(SiH)/v(SiD) ratios are found to be those expected on the basis of harmonic local mode calculations, if v(SiD) values are first divided by a factor R which normally lies in the range 1.010-1.011. Major deviations from this range indicate misassignments or Fermi resonances. Stretch-stretch interaction constants f" are tabulated, and agree excellently with ab initio values, where these are available. Where v ~ (Sill) values are known, the frequency sum rule is found to be obeyed closely. The v7 bands of Si2H6 and Si2D6 are reanalysed to yield an R value of 1.010. The v(SiH) data for disilanes then yield, in a "6 x 6" refinement, values of the three interaction force constants f~, f~ and f~, together with predictions of hitherto unlocated stretching fundamentals. Constancy of the R factor for different types of XH bonds is shown to be a consequence of Dennison's rules, and similar anharmonicity factors. 1335 d Ref. [14]. Ref. [15].