Synthesis and structural characterization of the μ-η1:Ph2PC5H4 ligand-containing transition-metal cluster and dinuclear complexes (μ-η1:Ph2PC5H4)(μ3-S)MFeCo(CO)7(M = Mo, W), (μ-η1:η5Ph2PC5H4)(μ3-RC)MCo2(CO)7 (M = Mo, W; R = Me, Ph), and (μ-η1:η5-Ph2PC5H4)CpMo2(CO)5 obtained from the studied isolobal displacement reactions

The isolobal displacement reaction of tetrahedral cluster (mu(3)-S)FeCo2(CO)(9) with isolobal reagents eta(5)-Ph2PC5H4(CO)(3)MLi (M = Mo, W) in THF at about 60 degrees C was found to give the mu-eta(1):eta(5)-Ph2PC5H4-containing tetrahedral clusters (mu-eta(1):eta(5)-Ph2PC5H4)(mu(3)-S)MFeCo(CO)(7) (1, M = Mo; 2, M = W), whereas tetrahedral clusters (mu(3)-RC)Co-3(CO)(9) (R = Me, Ph) reacted with eta(5)-Ph2PC5H4(CO)(3)MLi under the same conditions to afford the corresponding tetrahedral clusters (mu-eta(1):eta(5)-Ph2PC5H4)(mu(3)-MeC)MCo2(CO)(7) (3, M = Mo; 4, M = W) and (mu-eta(1):eta(5)-Ph2PC5H4)(mu(3)-PhC)MCo2(CO)(7) (5, M = Mo; 6, M = W). However, it was found that when tetrahedral cluster CpMoCo3(CO)(11) reacted with isolobal reagent eta(5)-Ph2PC5H4(CO)(3)MoLi under similar conditions, the corresponding tetrahedral cluster (mu-eta(1):eta(5)-Ph2PC5H4)CpMo2Co2(CO)(9) (7) was not produced, but instead the dinuclear complex (mu-eta(1):eta(5)-Ph2PC5H4)CpMo2(CO)(5) (8) was obtained unexpectedly. While 1-6 and 8 have been characterized by elemental analysis and spectroscopy, as well as by X-ray crystallography for 1-3 and 8, the possible pathways for formation of these products are suggested.