PROPERTIES AND REACTIVITY OF THE NEW [IR-4(MU-CO)(3)(CO)(5)(MU-PR(3))(PR(3))(2)] CLUSTERS, (PR(3)=PPH(X)PYL(3-X), PYL=2-PYRIDYL)

The complex Ir-4(CO)(12) was shown to react with pyridylphosphines to give Ir-4(mu-CO)(3)(CO)(5)(mu-PPh(2)pyl)(PPh(2)pyl)(2)] (1) Ir-4(mu-CO )(5)(CO)(5)(mu-PPhpyl(2))(PPhpyl(2))(2)] (2) and [Ir-4(mu-CO)(3)(CO)(5 )(mu-Ppyl(3))(Ppyl(3))(2)] (3) in which one of the phosphine ligands b ridges through coordination of P and N atoms. Clusters 1-3 were charac terized by H-1, P-31 NMR and IR spectroscopy. Variable-temperature 1H, P-31 and C-13 NMR spectra of 1-3 were investigated and the results ar e discussed. In solution under CO complexes 1-3 are in equilibrium wit h the clusters [Ir-4(mu-CO)(3)(CO)(6)(PR(3))(3)].