Chiral organotin complexes stabilized by C,N-chelating oxazolinyl-o-carboranes

Abstract

A series of chiral organotin halides containing 2-(4-R)-oxazolinyl-o-carboranes (R = i-propyl 1, t-butyl 2; Cab(Oxa)) was prepared from o-carborane with a chiral oxazoline auxiliary. X-ray structural analysis of the representative chiral organotin halide, [2-(4-i-propyl)-oxazolinyl-o-carboranyl]SnMe(2)Br (4), revealed the formation of a stable penta-coordinated tin center due to a N -> Sn interaction. Similar O -> Sn assisted intramolecular penta-coordinated tin complexes (9 and 10) were prepared from methoxy-o-carborane ligands, MeOCH(Z)-o-carborane (Z = H 7, Ph 8; Cab(OMe)), respectively, and a rigid o-carboranyl backbone provided the basic skeleton for the facile formation of organotin complexes. (C) 2009 Elsevier B.V. All rights reserved.