Reactivity and structural patterns of phenylphosphines in acetylene and acetylide carbonyl trinuclear ruthenium clusters

The acetylene [Ru3(?-CO)(CO)9{3-?2-(//)HCCR}] (1a: R?=?C(Me)CH2); 1b: and the acetylide [Ru3(-H)(CO)9{3-?2-(?)CCR}] (2a: R?=?C(Me)CH2; 2b: clusters have been synthesized from the reaction of [Ru3(CO)10(NCMe)2] with 2-methyl-1-buten-3-yne and 1-ethynylcyclohexene respectively. The reactions of the corresponding parallel acetylene 1a or 1b with triphenylphosphine or diphenylmethylphosphine yielded four isostructural compounds [Ru3(?-CO)(CO)8(L){3-?2-(//)HCCR}] (3a1: L?=?PPh3, 3a2: L?=?PPh2Me, R?=?C(Me)CH2; 3b1: L?=?PPh3, 3b2: L?=?PPh2Me, where, the alkynes are still coordinated to the metallic fragment as acetylene groups in a ?3-?2 parallel fashion. Also, the isomer compounds [Ru3(-H)(CO)8(L){3-?2-(?)CCR}] (4a1 and 5a1: L?=?PPh3, 4a2 and 5a2: L?=?PPh2Me, R?=?C(Me)CH2; 4b1 and 5b1: L?=?PPh3, 4b2 and 5b2: L?=?PPh2Me, ; and the disubstituted phenylphosphine clusters [Ru3(-H)(CO)7(L)2{3-?2-(?)CCR}] (6a1: L?=?PPh3, 6a2: L?=?PPh2Me, R?=?C(Me)CH2; 6b1: L?=?PPh3, 6b2: L?=?PPh2Me, were formed during each reaction. In these compounds, the parallel-acetylene group undergoes an oxidative addition and a rearrangement of the coordinated organic fragment to a 3-?2 perpendicular coordination mode of the CC axis by breaking acetylene CH bond to give a hydride ligand in each case. The synthesis of clusters [Ru3(?-CO)(CO)8(PPh3){3-?2-(//)HCCC6H22,4,5-Me3}] (3c1), [Ru3((-H)(CO)8(PPh3){3-?2-(?)-CCC6H22,4,5-Me3}] (4c1 and 5c1) and [Ru3(-H)(CO)7(PPh3)2{3-?2-(?)CCC6H22,4,5-Me3}] (6c1) are also described. All compounds have been characterized in solution by infrared spectroscopy and by 1H, 13C{1H} and 31P{1H} NMR. The molecular structures of compounds 2b, 3a1, 3b1, 4a1, 4c1, and 6b1 have been established by single crystal X-ray diffraction studies.