Highly asymmetric coordination of trimethylsilyl groups to tetrazole and triazole rings: an experimental and computational study in gaseous and crystalline phases

1-Trimethylsilyltetrazole, 1, has been synthesised from chlorotrimethylsilane and tetrazole in the presence of triethylamine as an auxiliary base. The structure of this compound has been determined in the crystalline phase by X-ray diffraction of a crystal grown in situ. The gas-phase structures of 1 and 1-trimethylsilyl-1,2,4-triazole, 2, have been determined by gas-phase electron diffraction (GED). An extensive investigation of these and related compounds by ab initio calculations is also reported. The angles between the rings and the substituents on N were of particular interest. It was found that the calculated difference of 15.5° between the CNSi and NNSi angles in 1 was mostly, but not entirely, an inherent property of the tetrazole ring and not due to a short Si···N interaction.