Isolation and structural characterisation of two sterically crowded diphosphanes

Under specific conditions the reduction of the chlorophosphanes R(Me2NCH2-2-C6H4)PCI or RPCl2 [R = (Me3Si)(2)CH] with LiAlH4 gives the diphosphanes {R(Me2NCH2-2-C6H4)P}(2) (2) and RPH-PHR (3), respectively in moderate to good yields. Compound 2 may be obtained in higher yield from the reaction of {R(Me2NCH2-2-C6H4)P}Li with PbI2. Compounds 2 and 3 have been characterised by multi-element NMR spectroscopy and the meso-diastereomers of both compounds have been characterised by X-ray crystallography. In the solid state both meso-2 and meso-3 adopt an antiperiplanar conformation. (C) 2002 Elsevier Science B.V. All rights reserved.