A Dative-Bonded Sulfur-Boron-Nitrogen Heterocycle

摘要

The new dative-bonded cyclic cotrimer-N(CH3)2-BH2-S(CH3)-BH2-N(CH3)2-BH2-is formed easily by generating the CH3SBH2 and (CH3)2NBH2 units from (CH3)2NB2H5 and either CH3SH or (CH3S)3B in the presence of supplementary (CH3)2NBH2 units, at 100-130C. By contrast, the cyclohexane-like trimer ((CH3)2NBH2)3, which has three (rather than two) axial methyl groups in steric contact, can be formed only by the aid of a very special catalyst. The cotrimer holds its CH3SBH2 and (CH3)2NBH2 units in less reactive form than in (CH3SBH2)n or the monomer and dimer of (CH3)2NBH2, for it reacts only very slowly with water, methanol, trimethylamine, or diborane at temperatures below 100C, but it is definitely more reactive than the trimer of (CH3)2NBH2. The cotrimer formula and structure are confirmed by hydrolytic analysis and the B and H nmr spectra. (Author)