Trimetallic complexes of the tripod ligand 1,1,1-tris(diphenylphosphinomethyl)ethane part I. Homotrimetallic cis,cis,cis and cis,trans,cis complexes of the type [(PtX 2-η-tripod) 2PtX 2] (XCl, I and CH 3)

Abstract

Complexes of types cis,cis,cis- and cis,trans,cis-[(PtX 2-η-tripod) 2PtX 2] (XCl, I and CH 3; tripod=1,1,1-tris(diphenylphosphinomethyl)ethane) have been isolated and have been shown by both 31P and 195Pt NMR spectroscopy to possess phosphino-bridged trimetallic structures. The assignment of these structures is established on the basis of 1 J(PtP) couplings and the coordination chemical shift, δP, of the dangling phosphino group of the monometallic complexes upon coordination. In both cis, cis, cis and cis, trans, cis geometries, the 31P NMR chemical shift of the chelating phosphorus atoms and the 195Pt NMR chemical shift for the [PtX 2(tripod)] complexes remain unperturbed upon coordination of the previously non-coordinated phosphorus. For the monomeric complexes of tripod, trends in the 31P and 195Pt NMR chemical shifts as a function of X parallel those which have previously been reported for analogous complexes which contain monodentate ligands.