Infrared spectroscopy studies and MNDO/d calculations in organosilylborane series

A series of organosilylboranes has been investigated by IR spectroscopy and semiempirical calculations (MNDO/d force field methods). Computational studies afforded Si-B stretching wavenumbers in good agreement with the experimental IR bands observed in the range of 480-650 cm(-1). It was shown that these characteristic Si-B bond vibrations depend on the structure of molecules and on the size of substituting groups. Thus, compounds possessing small and medium substituting groups (H, Me) and those having a symmetry element give pure Si-B stretching bands. In the case of silylboranes bearing bulky groups, assignments of bands involving Si-B vibrators. were achieved via comparison of experimental and theoretical IR spectra with those of reference molecules containing the parent organosilyl- or organoboryl moieties. An experimental absorption band near 600 cm(-1) could reasonably be assigned to nu(Si-B). (C) 2003 Elsevier Science B.V. All rights reserved.