Preparation and crystal structure of the dicarboranyl-magnesium bis(dioxane) adduct Mg(2-Me-1,2-C 2B 10H 10) 2·2C 4H 8O 2

Abstract

The preparation of Mg(2-Me-1,2-C 2B 10H 10) 2·2C 4H 8O 2 from the carboranyl Grignard reagent RMgBr (R = the methyl- ortho-carboranyl residue, 2-Me-1,2-C 2B 10H 10) by a dioxane-induced disproportionation reaction is described. An X-ray crystallographic study of the product has revealed a monomeric molecular structure R 2MgL 2 (L = 1,4-dioxane, C 4H 8O 2) in which the carboranyl groups and dioxane ligands provide the central magnesium atom with a distorted tetrahedral coordination sphere of two carbon and two oxygen atoms, with bond lengths MgC 2.156(5) Å, MgO 2.038(8) Å and bond angles CMgC 123.5(4)°, OMgO 99.5(5)°, distortions from regular tetrahedral angles attributable to the relative bulk of the carboranyl ligands.