Synthesis and structure of an acyclic dialkylstannylene

Abstract

The reaction between iPr 2 PCl and one equivalent of MeMgBr, followed by one equivalent of BH 3 ·SMe 2 , gives the phosphine-borane iPr 2 P(BH 3 )Me (4). Treatment of 4 with nBuLi, followed by Me 3 SiCl, gives the sterically demanding phosphine-borane {iPr 2 P(BH 3 )}(Me 3 Si) CH 2 (5) in good yield. Metalation of 5 with nBuLi yields {iPr 2 P(BH 3 )}(Me 3 Si)CHLi (6), which was crystallised as the TMEDA adduct [{iPr 2 P(BH 3 )}(Me 3 Si)CH]Li(TMEDA) (6a) and characterised by X-ray crystallography [TMEDA = N,N,N′,N′-tetramethylethylenediamine]. The reaction between two equivalents of in situ-generated 6 and Cp 2 Sn in toluene gives the dialkylstannylene [{iPr 2 P(BH 3 )}(Me 3 Si) CH] 2 Sn (7), which was crystallised from methylcyclohexane/THF as the rac diastereomer. X-ray crystallography reveals that stabilisation of the Sn centre in 7 is afforded by two agostic-type B-H…Sn interactions, one from each BH 3 group.