Mesityl-Phosphorus Compounds. Synthesis of a New Imino(Methylene)phosphorane and Its Dimers

摘要

The reaction of CCl4 with the sterically congested (silylamino) phosphine (Me3Si)2NP(R)CH2SiMe3 (compound 1, R double bond 2,4,6-Me3C6H2) unexpectedly yields the 4-membered P2N2 ring system (Me3SiCH double bond P(R)-NSiMe3)2 (compound 2). Heating of the dimer compound 2 under a dynamic vacuum results in distillation of the monomeric, 3-coordinate imino(methylene)phosphorane R-P(double bond CHSiMe3) (double bond NSiMe3) (compound 3). Compound 3 exhibits reasonable stability at room temperature but reverts to the dimer compound 2 on standing for a few days. Treatment of compound 3 with methanol affords the stable addition product Me3SiN double bond P (R) (OMe)CH2SiMe3 (compound 4). Direct bromination of the phosphine compound 1 occurs to give the expected P-bromophosphinimine compound 5 which, by reaction with LiOCH2CF3, is converted to Me3SiN double bond P (R) (OCH2CF3)CH2SiMe3 (compound 6). When either the dimer compound 2 or the monomer compound 3 is heated in a sealed tube, an isomeric, 4-membered PCPN dimer compound 7 is obtained quantitatively. Proton, (13)C, and (31)P NMR data are reported for the new compounds and the CCl4 reaction of compound 1 is contrasted to that observed for related systems. (Author)