Synthesis and characterization of 1,2-bis(phosphino)benzene (diphos) and related complexes of vanadium, chromium, iron and cobalt. X-ray crystal structures of MCl 2(DIPHOS) 2 (M = V, Cr and Fe) and [Fe(DIPHOS) 2(MeCN) 2](BPh 4) 2

Abstract

The interaction of transition metal dichlorides with the chelating diphosphine (diphos) ligands 1,2-bis(phosphino) benzene, 1,2-bis(2-propylphosphino) benzene and 1,2-bis(dimethylphosphino) benzene leads to the octahedral complexes trans-MCl 2(diphos) 2, (M = V, Cr, Fe or Co). Interaction of FeCl 2[1,2-(Me 2P)C 6H 4] 2 with NaBPh 4 in refluxing MeCN gives the nitrile complex trans-[Fe(NCMe) 2(diphos) 2](BPh 4) 2, whereas VCl 2[1,2-(C 3H 7PH) 2C 4H 4] 2 gives only the complex [V(CNMe) 6](BPh 4) 2. This difference is attributed to the weaker basicity (exemplified by the longer MP bond lengths) of the secondary phosphine ligand. X-ray crystal structures of the following compounds have been determined : MCl 2[1,2-(C 3H 7PH) 2C 6H 4] 2 (M = V, Cr or Fe) and [Fe(NCMe) 2[1,2-(Me 2P)C 6H 4] 2](BPh 4) 2. In all cases the octahedral complexes have trans-Cl or MeCN groups.