STRUCTURAL-ANALYSIS OF PLATINUM PHOSPHINE COMPLEXES BY 2-DIMENSIONAL P-31 NMR-SPECTROSCOPY

The synthesis and characterization of a new platinum(I) phosphine complex, [Pt2(mu-dppm)(eta-1-dppm)dppeCl]Cl, is reported. This unique complex is the first example of a stable Pt(I) dimer in which all three types of coordination possible for a diphosphine ligand are observed. To structurally characterize this complex, we have employed one- and two-dimensional P-31 NMR spectroscopy. Using 14 other structurally simpler platinum phosphine complexes, it is established that the P-31 homonuclear shift correlated spectroscopy (COSY) technique provides valuable information about both the phosphorus-phosphorus and platinum-phosphorus couplings, especially when the resonances in the one-dimensional spectra are poorly resolved. The 2J(Pt-P) and 3J(Pt-P) coupling constants are obtained from the relative positions of the observed cross-correlations with respect to the main phosphorus resonances. From the analysis of the coupling patterns observed and the coupling constants measured from the two-dimensional data sets, determination of the geometrical arrangement of the phosphine ligands is demonstrated. The structural assignment of the new Pt(I) complex is based on the analysis of its P-31 COSY map and further supported by the COSY studies of the other platinum complexes.