Thermally induced dual P–C bond cleavage routes from the imido-capped cluster Ru3(CO)7(μ3-CO)(μ3-NPh)(bpcd): synthesis, spectroscopic properties, and X-ray diffraction structures of Ru3(CO)7(μ3-CO)(μ3-NPh)(bpcd), Ru3(CO)5(μ2-CO)2(μ3-NPh)(μ2-PPh2)[μ,η1,η1-

The imido-capped cluster Ru3(CO)9(μ3-CO)(μ3-NPh) (1) reacts with the diphosphine ligand 4,5-bis(diphenylphosphino)-4-cyclopenten-1,3-dione (bpcd) to furnish both Ru3(CO)7(μ3-CO)(μ3-NPh)(bpcd) (2) and Ru3(CO)5(μ3-CO)(μ3-NPh)(bpcd)2 (3) as the major and minor products, respectively, under thermal and Me3NO activation. The thermolysis of cluster 2 affords the new triruthenium compounds Ru3(CO)5(μ2-CO)2(μ3-NPh)(μ2-PPh2)[μ,η1,η1-Cdouble bond; length as m-dashC(PPh2)C(O)CH2C(O)] (4), Ru3(CO)6(μ2-CO)(μ3-NPh)(μ-PhCO)[μ2,η2,η1-PPhCdouble bond; length as m-dashC(PPh2)C(O)CH2C(O)] (5), and Ru3(CO)9(μ3-NPh)(μ3-PPh) (6). Compounds 2–6 have been fully characterized in solution, and the molecular structures of 2, and 4–6 have been determined. Cluster 2 exhibits a nido-NRu3 core with a face-capping μ3-CO and a chelating bpcd ligand that occupies an equatorial and axial site. VT 31P NMR data indicate that the bpcd ligand in 2 undergoes a rocking motion between the equatorial and axial sites at the attached ruthenium center at elevated temperatures. Cluster 4 possesses a similar nido polyhedral core that is tethered by a bridging phosphido group and the 3e-donor moiety μ2,η2,η1-Cdouble bond; length as m-dashC(PPh2)C(O)CH2C(O). The structure of 5 reveals a hypho architecture containing a single Ru–Ru bond and where the three ruthenium centers are bridged by imido and benzoyl moieties and the seven-electron donor ligand μ2,η2,η1-PPhCdouble bond; length as m-dashC(PPh2)C(O)CH2C(O), which results from the cleavage of one the P–Ph bonds of the original bpcd ligand. The 50e cluster 6 exhibits a nido polyhedral core consisting of three Ru(CO)3 groups that are capped by a μ3-imido and μ3-phosphinidine unit. Cluster 6 represents the first structurally characterized example of a mixed PhN/PhP capped cluster belonging to the family of nido-Ru3(CO)9(μ3-EPh)2 clusters. The pertinent structural highlights associated with these clusters are discussed, and the lack of reactivity of the capping imido group with the bpcd ligand in Ru3(CO)7(μ3-CO)(μ3-NPh)(bpcd) during thermolysis is contrasted with the related benzylidyne-capped cluster PhCCo3(CO)7(bpcd).