Intense research has been carried out for diorganopolysilanes over 30 years because of their interesting thermochromism, solvatochromism, piezochromism, and ionochromism (West, R. J. Organomet. Chem. 1986, 300, 327−346). These chromisms are known to originate from main chain conformational change in Si-Si-Si-Si dihedral angle. To elucidate the relationship between conformational behavior and these chromisms, which are strongly dependent on physical environment (temperature, solvent polarity and so on), we have developed a molecular force field for diorganopolysilanes by providing the lack of parameters in the most reliable MMFF94s. Conformational profiles of 35 reference molecules were generated at MP2/6-311G(d,p) level, and then all energy minima (conformers) and the transition states were evaluated at MP4(sdq)/cc-pVTZ//MP2/6-311G(d,p) level by using Gaussian09. Using a set of the referenced conformational energies and geometries, the insufficient parameters of MMFF94s required for diorganopolysilane calculations were optimized by an original python-based program coupled with commercially available molecular mechanics package CONFLEX7 (H. Goto, E. Osawa, J. Am. Chem. Soc., 1989, 111, 8950–8951). Tests on the accuracy and applications of new force field implemented to CONFLEX7 will be reported in this conference.

Development of force field for diorganopolysilanes: Silicon, carbon, and hydrogen system

251st National Meeting (2016)

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