PLATINUM(II) COORDINATION CHEMISTRY OF BIS(DIPHENYLPHOSPHINO)AMINE

A spectroscopic and structural examination of the platinum(II) co-ordi nation chemistry of bis-(diphenylphosphino)amine (dppa) and bis(diphen ylphosphino)methylamine (dppma) has been made. The complexes [Pt(dppa) Cl2], [Pt(dppma)Cl2], [Pt(dppa)(CN)2], [Pt(dppma)(CN)2], [Pt(dppa)2]2 and [Pt(dppma)2]2+ as the chloride, iodide and tetrafluoroborate salt s, [Pt(Ph2PNPPh2)2], trans-[Pt-(dppa-P)2(CN)2] and [Pt2(mu-dppa)2(CN)2 [ have been prepared. The solid-state structures of [Pt(dppa)2][BF4]2. MeCN,[Pt(dppma)2][BF4]2 and trans-[Pt(dppa-P)2(CN)2] have been determi ned by X-ray crystallography. The crystallographic examination permits a critical evaluation of the nature of the strain in the four-membere d rings formed by ligand chelation to a transition-metal centre. Struc tural and theoretical data suggest that bis(diphenylphosphino)amine ch elate complexes should be more strained than the corresponding bis(dip henylphosphino)methane (dppm) complexes. The preference of Pt(II) for binding to dppa rather than dppm implies the formation of a stronger P t-P bond in complexes of the former ligand.