PALLADIUM(II) AND PLATINUM(II) COMPLEXES FORMED FROM C6H4-1,3-(CH(2)PCY(2))(2) (CY=CYCLOHEXYL) - CRYSTAL-STRUCTURES AND MOLECULAR-STRUCTURES OF [PDX(C6H3-2,6-(CH(2)PCY(2))(2))], X=CL AND BR

The reaction of C6H4-1,3-(CH(2)PCy(2))(2) (Cy = cyclohexyl) with [PdCl 2(NCPh)(2)] gave mainly [PdCl2{C6H4-1,3-(CH(2)PCy(2))(2)}]. which was converted into [PdCl{C6H3-2,6-(CH(2)PCy(2))(2)}] on prolonged reflux, whereas C6H4-1,3-(CH(2)PCy(2))(2) reacted with [PdBr2(PPh(3))(2)] to g ive mainly [PdBr{C6H3-2,6-(CH(2)PCy(2))(2)}]. Only [PtCl2{C6H4-1,3-(CH (2)PCy(2))(2)}](n) was formed in the analogous reaction with [PtCl2(NC Ph)(2)]. X-ray analysis showed that [PdCl{C6H3-2,6-(CH(2)PCy(2))(2)}] and [PbBr{C6H3-2,6-(CH(2)Pcy(2))(2)}] are isostructural. Both molecule s display a conformation of the terdentate PCP ligand that is differen t-from that recently reported for several related molecules. It is con cluded that the conformation adopted by C6H3-2,6-(CH(2)PR(2))(2) ligan ds appears to be dominated by the steric demand of the phosphorus subs tituents.