Carbonyl−Metal Clusters with Mixed O,N-Donor Ligands: Reactivity of the Ureato Cluster [Ru3(μ-H)(μ3-HNCONMe2)(CO)9] with Phosphines. Structural Characterization of a Triphenylphosphine Derivative and of a Bis(diphenylphosphido) Derivative Which Also Contains a Bridging η1-Phenyl Ligand

The ureato-bridged carbonyl cluster [Ru 3 (μ-H)(μ 3 -HNCONMe 2 )(CO) 9 ] ( 1 ) (H 2 NCONMe 2 = N, N -dimethylurea) reacts with 1 equiv of triphenylphosphine or diphenylphosphine to give the isostructural derivatives [Ru 3 (μ-H)(μ 3 -HNCONMe 2 )(L)(CO) 8 ] (L = PPh 3, PPh 2 H). The X-ray structure of [Ru 3 (μ-H)(μ 3 -HNCONMe 2 )(PPh 3 )(CO) 8 ] indicates that the substitution has taken place on an equatorial position cis to the bridging NH fragment. Treatment of 1 with bis(diphenylphosphino)methane (dppm) affords a mixture of the symmetric ( C s ) and asymmetric ( C 1 ) isomers of [Ru 3 (μ-H)(μ 3 -HNCONMe 2 )(μ-dppm)(CO) 7 ]. All these reactions take place at room temperature. The phenyl-bridged bis(diphenylphosphido) derivative [Ru 3 (μ-η 1 -Ph)(μ 3 -HNCONMe 2 )(μ-PPh 2 ) 2 (CO) 6 ] has been prepared by reaction of 1 with 2 equiv of PPh 3 in the presence of alumina and has been characterized by X-ray diffraction methods. The thermolysis of [Ru 3 (μ-H)(μ 3 -HNCONMe 2 )(PPh 2 H)(CO) 8 ] in refluxing THF leads to the phosphido-bridged derivatives [Ru 3 (μ 3 -HNCONMe 2 )(μ-PPh 2 )(μ-CO) 2 (CO) 6 ] and [Ru 3 (μ-H)(μ 3 -HNCONMe 2 )(μ-PPh 2 ) 2 (CO) 6 ]. It has been observed that carbonyl substitution reactions on compound 1 are easier than those previously reported on clusters containing N- and/or P -donor bridging ligands. This seems to be related to the hard−soft character of the bridging ligand: the harder the ligand the more reactive is the cluster in carbonyl substitution reactions.