Reactivity of Triruthenium Furyne and Thiophyne Clusters: Multiple Additions of Thiolato and Selenolato Ligands through Oxidative Addition of S–H and Se–H Bonds
Reactions of 50-electron furyne and thiophyne clusters Ru3(CO)7(μ-H)(μ3-η2-C4H2E){μ-P(C4H3E)2}(μ-dppm) (1, 2; E = O, S) with thiols, dithiols, and benzeneselenol leads to the oxidative addition of the E–H bonds followed by concomitant elimination of the alkyne (probably as the alkene) to afford a range of new thiolato and selenolato triruthenium complexes. Addition of PhSH or iPrSH in boiling benzene affords the 48-electron clusters Ru3(CO)5(μ-SR)2{μ-P(C4H3E)2}(μ-dppm)(μ-H) (3–6; E = O, S; R = Ph, iPr) resulting from the addition of 2 equiv of thiol. In contrast, analogous reactions with 1,2-ethanedithiol and 1,3-propanedithiol yield the 50-electron clusters Ru3(CO)3{μ-S(CH2)nS)2{μ-P(C4H3E)2}(μ-dppm)(μ-H) (7–10; E = O, S; n = 2, 3), in which four S–H bonds have been activated. A similar multiple addition reaction is seen upon addition of PhSeH to 1, affording the tetraselenolato complexes Ru3(CO)4(κ1-SePh)(μ-SePh)3{μ-P(C4H3O)2}(μ-dppm)(μ-H) (11) and Ru3(CO)3(μ-SePh)4{μ-P(C4H3O)2}(μ-dppm)(μ-H) (12). Reaction of 2 with PhSeH gave the tetraselenolato complex Ru3(CO)4(κ1-SePh)(μ-SePh)3{μ-P(C4H3S)2}(μ-dppm)(μ-H) (13) together with bis(seleno)-capped Ru3(CO)5{PPh(C4H3S)2}(μ3-Se)2(μ-SePh)2(μ-dppm) (14) resulting from further cleavage of two selenium–carbon bonds and formation of a new carbon–phosphorus bond. The new clusters have been characterized by a combination of analytical and spectroscopic methods, and the molecular structures of 3, 4, 7, 8, and 11 have been determined by single-crystal X-ray diffraction studies. Complexes 7–10 are examples of 50-electron clusters containing three apparent metal–metal bonds; however, DFT calculations carried out for 7 show that the longest metal–metal interaction of 3.119 A is actually held in place by the bridging thiolato and diphosphine ligands and does not represent a direct metal–metal bonding interaction.