Jean-Luc Faure

The Dramatic Influence of Diamidoamine Ligands on the Structure and Reactivity of Low-Valent Tin and Bismuth Derivatives

The dilithium salts of N-methyl-N′,N′′-bis(diisopropyl)- and -(trimethylsilyl)-diethylenetriamine 1a,b react with SnCl2 affording the corresponding stannylenes 2a,b in 60 and 80% yield, respectively. Compound 1b also reacts with BiCl3 to give the bismuth chloride 5 (90% yield). Derivatives 2b and 5 have a symmetrical bicyclic structure and are monomeric both in solution and in the solid state. When 2b is treated with BiCl3 or PCl3, an oxidation reaction leads to the hypercoordinated tin(IV) dichloride 3 (58% yield), or a transmetallation gives rise to the oniophosphane 4 (95% yield), respectively. Transmetalation reactions also occurred when 5 was treated with AlCl3, GaCl3 or SnCl2 affording the corresponding aluminum chloride 6 (81% yield), gallium chloride 7 (38% yield) or tin dichloride 3 (38% yield). The observed reactivity for 2 and 5 is compared to that reported for Veiths stannylene or bismuth chloride.

EVIDENCE FOR A TRANSIENT ACYLPHOSPHENIUM ION

Abstract The reaction of bis(diisopropylamino)pivaloylphosphine 1 and bis(diisopropylamino)p-toluoylphosphine 2 with strong Bronsted acids (HBF4 and CF3SO3H) is reported. In the case of the p-toluoylphosphine 2 a transient acylphosphenium ion 8 is formed and trapped by the starting phosphine affording C-phosphonio phosphaalkene 5.