Selective Synthesis of N-Methylanilinooligosilanes

Syntheses and Molecular Structures of Liquid Pyrophoric Hydridosilanes

Trisilane, isotetrasilane, neopentasilane, and cyclohexasilane have been prepared in gram scale. In-situ cryo crystallization of these pyrophoric liquids in sealed capillaries on the diffractometer allows access to the single crystal structures of these compounds. Structural parameters are discussed and compared to gas-phase electron diffraction structures from literature and with the results from quantum chemical calculations. Significantly higher packing indices are found for the silanes compared to the corresponding alkanes. Radiation with ultraviolet light (365 nm) and parallel ESR (EPR) measurement shows that cyclohexasilane is easily split into radicals, which subsequently leads to the formation of branched and chain-like oligomers. The other compounds form no radicals under these conditions. NMR spectra of all four compounds have been recorded.

Insertion of phenyl isocyanate into mono- and diaminosilanes

The aminosilanes MenSi(NRR′)4−n (n=2,3) with NRR′=ethylamino (NHEt), n-propylamino (NH n Pr), sec-butylamino (NH s Bu), n-octylamino (NH n Oct), n-dodecylamino (NH n Dodec), allylamino (NHAll), tert-butylamino (NH t Bu), diethylamino (NEt2), and anilino (NHPh) were synthesized and their reactions with phenyl isocyanate were studied. In all cases of these silanes Me3SiNRR′ and Me2Si(NRR′)2 formal insertion of the –NCO group into their Si–N bonds was observed, i.e. formation of products with Si–N (rather than Si–O) bonds was found. In some cases, the products could be crystallized and their molecular structures have been elucidated with single-crystal X-ray diffraction analyses.