VIBRATIONAL SPECTRA, AB INITIO CALCULATIONS AND CONFORMER STABILITY OF 1,3-DIMETHYL-1,1,3,3-TETRAKIS(TRIMETHYLSILYL)TRISILANE (SiMe3)2MeSiSiH2SiMe(SiMe3)2

Abstract: Quantum chemical ab initio calculations at the RHF level of theory predict five minima with very unusual SiSiSiSi dihedral angles on the internal rotation potential energy surface for (SiMe3)2MeSiSiH2SiMe(SiMe3)2. Temperature dependent Raman spectroscopy has been used to correlate these results with vibrational spectra. 1,3-Disubstituted propanes, for instance XCH2CH2CH2X with X = halogen, possess four minima on the potential energy surface (PES) for internal rotation, commonly named anti/anti, anti/gauche, gauche(+)/gauche(+) and gauche(+)/gauche(-) as illustrated in Figure 1 below. Ab initio calculations predict that 1,3-disubstituted trisilanes XSiH2SiH2SiH2X with monoatomic substituents X behave identical in this respect [1].