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 bridges through coordination of P and N atoms. Clusters 1-3 were characterized 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 are discussed. In solution under CO complexes 1-3 are in equilibrium with the clusters [Ir-4(mu-CO)(3)(CO)(6)(PR(3))(3)].