Disilanes with Pentacoordinate Si Atoms by Carbon Dioxide Insertion into Aminodisilanes: Syntheses, Molecular Structures, and Dynamic Behavior

The insertion of carbon dioxide into the Si-N bonds of aminodisilanes ((RR'N) _n Me_3-n Si)₂ affords carbamoyloxydisilanes ((RR'NC(O)O) _n Me_3-n Si)₂. Some of the obtained insertion products feature pentacoordinate silicon atoms in the solid state and in solution, with two carbamoyloxy moieties bridging the Si-Si bond. The aminodisilanes and their insertion products were extensively analyzed, including single-crystal X-ray structure analyses. The temperature dependence of the higher coordination was investigated using variable temperature NMR experiments.

(3,5-Dimethyl-1H-pyrazol-1-yl)trimethylsilane

At 1.782 (2) Å, the Si—N bond is substanti­ally longer than is found in comparable (3,5-di­methyl­pyrazol­yl)silanes. The tri­methyl­silyl group adopts a staggered conformation with respect to the planar 3,5-di­methyl­pyrazolyl unit. C—H⋯N hydrogen bonds between neighboring mol­ecules form a strand of mol­ecules along the b-axis direction.

The title compound, C₈H₁₆N₂Si, crystallizes in the the ortho­rhom­bic space group P2₁2₁2₁ with one mol­ecule in the asymmetric unit. The Si—N bond is 1.782 (2) Å, which is substanti­ally longer than is found in comparable (3,5-di­methyl­pyrazol­yl)silanes. The tri­methyl­silyl group adopts a staggered conformation with respect to the planar 3,5-di­methyl­pyrazolyl unit. C—H⋯N hydrogen bonds between neighboring mol­ecules form a strand of mol­ecules along the b-axis direction.

Five- and six-fold coordinated silicon in silicodiphosphonates: short range order investigation by solid-state NMR spectroscopy

Silicodiphosphonates synthesized by two different pathways show interesting chemical shifts of five- and sixfold coordinated silicon.