A set of force constants common for SiH3-X molecules

A set of common force constants was obtained for the silyl group (SiH3-X) u sing as experimental data the frequencies from silyl cyanide (X = -CN), iso cyanate (X = -NCO) and isothiocyanate (X = -NCS). initial values of the for ce constants were obtained by ab initio methods, using three different leve ls of theory, Hartree-Fock, second order Moller-Plesset and Density Functio nal Theory. We have analysed the variation of the common block of force con stants for the silyl group with respect to the nature of the X-substituent. (C) 1999 Elsevier Science B.V. All rights reserved.