Nitrogen ylides. V. Coordination chemistry of trimethylammonium methylide

Article abstract of DOI:10.1021/ic50072a015

The coordination chemistry of trimethylammonium methylide, (CH₃)₃N⁺C^-H₂, with various Lewis acids is examined. The crystalline BF₃ complex (CH₃)₃N⁺CH₂B^-F ₃ appears to ionize in nitromethane giving [(CH₃)₃N⁺CH₂BF₂]F ^- and decomposes thermally giving (CH₃)₃NBF₃ and ethylene. The BCl₃ complex was prepared and characterized by nmr but it could not be purified. No BH₃ complex could be detected chemically or spectroscopically. Trialkylborane adducts can be prepared, but they undergo a rearrangement to give products resulting from methylene insertion into the B-C bond. The Al(CH₃)₃ complex was isolated and was also found to rearrange when heated to 120° to give products which can be considered to result from a methylene insertion into the Al-C bond. The latter rearrangement is rather unusual in aluminum chemistry. Compounds of the following type were also isolated: [(CH₃)₃N⁺CH₂M(CH₃) ₃]Br^-, where M = Si, Ge, Sn. The silicon and germanium compounds decompose thermally by N-demethylation whereas the tin complex decomposes giving trimethylamine, trimethylbromostannane, and, presumably, polymethylene. Complexes with dipentylzinc were not observed, and two mercury-containing complexes could not be purified. The behavior of nitrogen ylide adducts is compared with phosphorus and arsenic ylide adducts.