Atrane and Quadroped Frameworks in Early Transition Metal and Silicon GroStereochemistry: Monomers and Oligomers

摘要

An exploration of the chemistry of silatranes and azasilatranes has been carriedout. The first isolation and structural characterization of silatrane adducts in which the exocyclic axial oxygen behaves as a Lewis base site was accomplished. Azasilatrane phosphine-nitrogen complexes were prepared with Lewis acid sites on the complex bonding to the axial oxygen. An axial silatranium cation was prepared. The range of axial-substituents for azasilatranes was explored and found to be limited to H, OR, OAr, R, and Ar. Attempts to obtain pentacoordination by nitrogen by replacing the axial hydrogen by azide using trimethylsilylazide resulted instead in trimethylsilyl/substitution of the equatorial nitrogens and an azide salt. Pyrolysis of the azide salt afforded the pentacoordinated azide. Nitrogen pentacoordination was also obtained from a thioisocyanide salt. A number of other equatorial nitrogen substituted azasilatranes were prepared. Attempts to couple azasilatrane to a Si-Si bonded dimer were unsuccessful. Azasilatrane-based polymers were prepared and characterized. The azasilatrane studies were extended to azastannatranes.