The influence of nitrosyl and allyl ligands on the formation of metalmetal bonds in bimetallic complexes containing S2CPCy3 bridges

The reactions of the anion [X(CO)2Mo(μ-S2CPCy3)Mo(CO)3]− (X=NO, η3-C3H5) with Ph2PCl afforded the products [(ON)(CO)2Mo(μ-PPh2)(μ-S2CPCy3)Mo(CO)3] (3) and [(η3-C3H5)(CO)Mo(μ-PPh2)(μ-S2CPCy3)Mo(CO)3] (4), respectively. The chemical shifts of the resulting μ-PPh2 ligands in the 31P{1H} NMR spectra indicate that the two molybdenum atoms are not bonded in 3, but are directly bonded in 4. The selenido-bridged binuclear complexes [X(CO)2Mo(μ-SePh)(μ-S2CPCy3)M(CO)3] (X=NO, M=Mo, 5a; M=W, 5b; X=η3-C3H5, M=Mo, 6a; M=W, 6b) were synthesized by the reactions of the corresponding anions [X(CO)2Mo(μ-S2CPCy3)MCO)3]− with PhSeI. The influence of the nitrosyl and allyl ligands on the formation of metalmetal and metalcarbon bonds in bimetallic complexes containing both S2CPCy3 and PPh2 bridges is discussed.