Reactions of (p-Cymene)Ru(S2C2B10H10) with 1,1-Diphenyl-2-Propyn-1-Ol: Synthesis and Structural Diversity of Novel Carborane-Incorporating Ruthenium Complexes

Abstract The reaction of the dinuclear precursor [(p‑cymene)RuCl2]2 with ortho‑carborane, elemental sulfur and 1,1‑diphenyl‑2‑propyn‑1‑ol (HC≡CC(OH)Ph2) yields two carborane‑incorporating ruthenium complexes via divergent pathways. Besides the known B–H activation product (p‑cymene)Ru[H9B10C2S2CH2CC(OH)Ph2] (2), a novel complex (p‑cymene)Ru(H10B9C2S2CHCCPh2) (1) was isolated and fully characterized. Its formation proceeds through initial dehydration of the alkynol to give an allenylidene intermediate, followed by attack of two sulfur atoms at the C=C=CPh2 unit and concomitant extrusion of one boron atom from the closo‑C2B10H10 cage, resulting in a rare nido‑C2B9 metallacyclic framework. Complex 1 was characterized by IR, NMR, MS, elemental analysis, and single‑crystal X‑ray diffraction. It crystallizes in the monoclinic space group P21/n with unit‑cell parameters a = 17.8494(15) Å, b = 10.2272(9) Å, c = 18.7853(16) Å, β = 92.9220(10)°, V = 3424.8(5) Å3, and Z = 4. Refinement converged to R = 0.0525 and ωR = 0.1283 for 5094 observed reflections [I > 2σ(I)].