Azomethine derivatives. Part VIII. Preparation of some diphenylketiminosilanes, and the use of diphenylketiminotrimethylsilane to prepare diphenylketiminoboranes

Abstract

Improved procedures for the preparation of Ph₂C:NSiR₃(R = Me, Et, or Ph) from R₃SiCl + Ph₂C:NLi are described. Ph₂C:NSiPh₃ can also be prepared from Ph₃SiCl + 2Ph₂C:NH. SiCl₄ and 4Ph₂C:NLi give the new compound (Ph₂C:N)₄Si.

Reactions between Ph₂C:NSiMe₃(I) and boron halides, generally in toluene, provide convenient routes to diphenylketiminoboranes. The trihalides BF₃(as BF₃, OEt₂),BCl₃, and BBr₃ with (I) give diphenylketiminoboron dihalides Ph₂C:NBX₂. With two molecules of (I) the same trihalides give Ph₂C:NBX₂+(Ph₂C:N)₃B, apparently through disproportionation of the monohalides (Ph₂C:N)₂BX, which could not be isolated. BCl₃ with three molecules of (I) gives (Ph₂C:N)₂B. Similar reactions between (I) and PhBCl₂, the catechol derivative C₆H₄O₂BCl, Ph₂BCl, and (mesityl)₂BF have been used to prepare two new apparently dimeric ketiminoboranes, (Ph₂C:NBPhCl)₂ and (Ph₂C:NBO₂C₆H₄)₂, and three new monomeric ketiminoboranes (Ph₂C:N)₂BPh, Ph₂C:NBPh₂, and Ph₂C:NB(mesityl)₂.

I.r. spectroscopic details of the ketimino-silanes and -boranes are given, and the mass spectrum of (Ph₂C:N)₄Si is briefly discussed.