Synthesis, molecular structure and reactivity of the first secondary carbaboranylbisphosphine 1,2-bis(phenylphosphino)-1,2-dicarba- closo-dodecaborane(12)

Abstract

The reaction of a diastereomeric mixture of 1,2-bis(phenylchlorophosphino)-1,2-dicarba- closo-dodecaborane(l2) ( 1) with LiAlH 4, followed by hydrolysis with H 2O, gives a 4 : 1 mixture of rac- and meso- 1,2-bis(phenylphosphino)-1,2-dicarba- closo-dodecaborane(12) ( 2a, b) or 1-phenylphosphino-1,2-dicarba- closo-dodecaborane(12) ( 3), depending on the stoichiometry employed. A mixture of 2a, b reacts with sulfur in undecane at 190°C or without solvent at 105–110°C to give exclusively the cyclic anhydride of 1,2-bis(phenylthiophosphoryl)-1, 2-dicarba- closo-dodecaboranyl(12)-dithiodiphosphinic acid ( 6). 2, 3 and 6 were characterised spectroscopically ( 1H, 31P, 11B, 13C NMR, IR, MS) and X-ray structure determinations were carried out on the racemic isomers 2a and 6.