Thermal transformations of tris(2-thienyl)phosphine (PTh3) at low-valent ruthenium cluster centers: Part I. Carbon–hydrogen, carbon–phosphorus and carbon–sulfur bond activation yielding Ru3(CO)8L{μ-Th2P(C4H2S)}(μ-H) (L = CO, PTh3), Ru3(CO)7(μ-PTh2)2(μ3-η2-C4H2S), Ru4(CO)9(μ-CO)2(μ4-η2-C4H2S)(μ4-PTh) and Ru5(CO)11(μ-PTh2)(μ4-η4-C4H3)(μ4-S)

Abstract Reaction of Ru 3 (CO) 12 with tris(2-thienyl)phosphine (PTh 3 ) in CH 2 Cl 2 at room temperature or in THF in the presence of a catalytic amount of Na[Ph 2 CO] furnishes the carbonyl substitution products Ru 3 (CO) 11 (PTh 3 ) ( 1 ), Ru 3 (CO) 10 (PTh 3 ) 2 ( 2 ), and Ru 3 (CO) 9 (PTh 3 ) 3 ( 3 ). Heating 1 in toluene affords the cyclometalated cluster Ru 3 (CO) 9 {μ-Th 2 P(C 4 H 2 S)}(μ-H) ( 4 ) resulting from carbonyl loss and carbon–hydrogen bond activation, and both 4 and the substituted derivative Ru 3 (CO) 8 {μ-Th 2 P(C 4 H 2 S)}(PTh 3 )(μ-H) ( 5 ) resulted from the direct reaction of Ru 3 (CO) 12 and PTh 3 at 110 °C in toluene. Interestingly, thermolysis of 2 in benzene at 80 °C affords 5 together with phosphido-bridged Ru 3 (CO) 7 (μ-PTh 2 ) 2 (μ 3 -η 2 -C 4 H 2 S) ( 6 ) resulting from both phosphorus–carbon and carbon–hydrogen bond activation of coordinated PTh 3 ligand(s). Cluster 6 is the only product of the thermolysis of 2 in toluene. Heating cyclometalated 4 with Ru 3 (CO) 12 in toluene at 110 °C yielded the tetranuclear phosphinidine cluster, Ru 4 (CO) 9 (μ-CO) 2 (μ 4 -η 2 -C 4 H 2 S)(μ 4 -PTh) ( 7 ), resulting from carbon–phosphorus bond scission, together with the pentaruthenium sulfide cluster, Ru 5 (CO) 11 (μ-PTh 2 )(μ 4 -η 4 -C 4 H 3 )(μ 4 -S) ( 8 ), in which sulfur is extruded from a thiophene ring. All the new compounds were characterized by elemental analysis, mass spectrometry, IR and NMR spectroscopy, and by single crystal X-ray diffraction analysis in case of clusters 4 , 6 , 7 , and 8 . Cluster 4 consists of a triangular ruthenium framework containing a μ 3 -Th 2 P(C 4 H 2 S) ligand, while 6 consists of a ruthenium triangle containing η 2 -μ 3 -thiophyne ligand and two edge-bridging PTh 2 ligands. Cluster 7 exhibits a distorted square arrangement of ruthenium atoms that are capped on one side by a μ 4 -phosphinidene ligand and on the other by a 4e donating μ 4 -η 2 -C 4 H 2 S ligand. The structure of 8 represents a rare example of a pentaruthenium wing-tip bridged-butterfly skeleton capped by μ 4 -S and μ 4 -η 4 -C 4 H 3 ligands. The compounds 4 , 6 , 7 , and 8 have been examined by density functional theory (DFT), and the lowest energy structure computed coincides with the X-ray diffraction structure. The hemilabile nature of the activated thienyl ligand in 4 and 6 has also been computationally investigated.