Silver(I) bromide complexes of the rigid diphosphanes 1,2-bis(diphenylphosphano)benzene (dppbz) and 4,5-bis(diphenylphosphano)-9,9-dimethyl-xanthene (xantphos): Crystal structures of [Ag(μ2-Br)(dppbz)]2, [AgBr(xantphos)] and [AgBr(xantphos)(py2SH)]

Reaction of silver(I) bromide with equimolar amounts of the rigid diphos ligands 1,2-bis(diphenylphosphano)benzene (dppbz) and 4,5-bis(diphenylphosphano)-9,9-dimethyl-xanthene (xantphos) in acetone and acetonitrile led to the corresponding chelates [Ag(μ2-Br)(dppbz)]2 (1) and [AgBr(xantphos)] (2). Treatment of 1 and 2 with pyridine-2-thione (py2SH) in ethanol gave the mixed-ligand complexes [AgBr(dppbz)(py2SH)] (3) and [AgBr(xantphos)(py2SH)] (4), respectively. Compounds 1, 2 and 4 have been characterized by X-ray diffraction, establishing distorted tetrahedral or trigonal planar coordination geometries of the silver atoms.

The behaviour of the diphos ligands 1,2-bis (diphenylphosphano)benzene (dppbz) and 4,5-bis(diphenylphosphano)-9,9-dimethylxanthene (xantphos) towards coordination of Ag(I) bromide in the presence of pyridine-2-thione has been investigated. Both diphosphanes adopt the chelating coordination mode, however two types of products have been obtained, namely a halide bridged dimer with tetrahedrally coordinated AgI centers for dppbz and monomeric trigonal complexes in the case of xantphos.Figure optionsDownload as PowerPoint slide