1,2-Dimethyl-1,2-Disila-Closo-Dodecaborane(12), A Silicon Analog of an Ortho-Carborane: Synthesis; X-ray Crystal Structure; NMR, Vibrational and Photoelectron Spectra; Bonding.

摘要

The reaction of (CH3)2Si(NMe2)2 with BlOH14 Yields a polymer, BlOH12.Me2NSi(CH3)2NMe2n, whose pyrolysis in a stream of ammonia gives hexagonal boron nitride containing 'a' little silicon nitride. In contrast, CH3(H)Si(NMe2)2 reacts with BlOH14 to give 1,2-dimethyl-1,2-disila-closo-dodecaborane(12) (DMSB), an air-sensitive solid, the structure of whose 1:1 benzene solvate was determined by X-ray diffraction. This compound crystallizes in the space group P ccn ( 56) with a 10.081(1) b = 10 . 666(8) A, c = 16.130(5) A, V = 1734(2)A3 and Z = 4. Final R = 0.044 and RW = 0.058. The 1H, 13C, 29Si and 11B NMR spectra and mass spectrum of DMSB are reported. Its vibrational spectrum (Raman, 5-3600 cm-1 ; IR, 200-3600 cm-1) has been measured and compared with that of ortho-carborane. A study of its He(I) photoelectron spectrum led to the conclusion that DMSB is the most electro rich cluster of type XYB1OH1O with two adjacent main group element centers known.