Quantum chemical studies on molecular structural conformations,energetic of methyl (methylene) silane

Recently, silicon based reactive diluents have been paid many attentions because silicon-containing compounds usually have outstanding chemical and thermal stability, and insulativity. These interesting investigations have proved the advantages of silicon based reactive diluents; meanwhile, they also suggest that the chemical structure of silicon-containing compounds should be carefully designed to guarantee the elaboration of these advantages [۱,۲].We report our findings on relative energy, geometric properties of methyl (methylene) silane and its derivatives (see Fig.۱). Geometry optimizations are carried out by B۳LYP method. This is using ۶-۳۱۱++G** basis set of the Gaussian ۹۸ system of programs [۳]. The investigation in water solution was carried out by means of the self-consistent reaction field (SCRF) method [۴] at the B۳LYP/۶-۳۱۱++G** level of theory. To confirm the nature of the stationary species, frequency calculations are carried out. For minimum state structures, an only real frequency value is accepted. In order to find substituent effect on methyl (methylene) silane, theoretical study via DFT method is employed in the manuscript. The following substituents are taken into considerations: NO۲ and CH۳.In this work, an AIM-analysis of the topology of the charge density were used to investigate the influence of the substituents at the methyl (methylene) silane on the structural, electronic and energetic properties of these constitutional isomers (see Fig. ۲.). Changeability of the C–Si, C-N and C–C bond lengths was analyzed in terms of the natural bond orbital (NBO) method.According to all of the theoretical calculations, the stability orders (ǻE in kcal/mol) for the methyl (methylene) silane in gas phase and solutions are as follows:NO۲ > CH۳ > HGeometrical parameters showed that the calculated geometric parameters for methyl (methylene) silane and its derivatives in gas phase, water, THF and DMSO solutions were very similar.

کلیدواژه ها:

methyl (methylene) silane ، ab initio method ، DFT method ، solvent effect