Cyclotri- and Cyclodisilazanes, DFT Calculations

A possible isomer of the cyclotrisilazane (Me2Si-NH)3, A, is a cyclodisilazane HN(SiMe2)2NSiMe2NH2, B, with an exocyclic SiMe2NH2 group. 

Density functional theory (DFT) calculations have been carried out to elucidate the structure and energetics of the various isomeric (Si-N) rings as well as the corresponding anions and dianions. The local minima on the potential energy surfaces were verified by computation of the eigenvalues of the respective Hessian matrices. From these, harmonic vibrational frequencies and the zero-point vibration corrected energetics were calculated. The calculations were carried out for isolated molecules in the gas phase. The theoretical results are expected to be reliable for molecules in non-polar or weakly aprotic polar solvents. 

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