Closo and Hyper-Closo Ten-Vertex Ruthenacarboranes Containing Chelating Alkenylphosphine Ligands

Article abstract of DOI:10.1021/ja00538a014

Reactions of 1-3-R²-6,6-(PPh3)2-6,2,3-RuC2B7H7> (I) with (o-styryl)diphenylphosphine (R^1,2 = H, CH3; R¹ = H, R² = Ph), (o-allylphenyl)diphenylphosphine (R^1,2 = H, CH3), and Ph_3-nP(CH2CH2CH=CH2)_n (n = 1, 2; R^1,2 = CH3) afforded the 16e^- ruthenacarborane complexes 1R²)> (IIa-g), in which the alkenylphosphine (L) functions as a bidentate ligand.The crystal structure of (IId) was determined from three-dimensional X-ray counter data.The complex crystallizes in the monoclinic system, space group P2₁/c, with a = 11.740(3) Angstroem, b = 15.185(5) Angstroem, c = 21.748(7) Angstroem, β = 137.43(2) grad, and Z = 4.Refinement of 4168 independent reflections with I > 3?(I) led to a final value of R = 4.0percent.The structure of this complex may best be described in terms of a C2B7 fragment of arachno geometry which occupies nine vertices of an 11-vertex octadecahedron with a ruthenium atom in a nonvertex position and within bonding distance of six atoms in the open face.The observed distortion from the common ten-vertex bicapped square antiprismatic structure is thought to be a result of the perturbation of the polyhedral skeletal bonding induced by the 16-electron Ru^II center.Reaction of IIb with carbon monoxide displaced the coordinated alkenyl side chain to yield the 18e^- Ru^II complex (IIIa) .Reactions of Ph_3-nP(CH2CH2CH=CH2)_n (n = 1,2) with produced the fluxional complexes 2-6,2,3-RuC2B7H9> (IV a,b) which exhibit butenyl side-chain exchange and undergo closo-hyper-closo equilibria as evidenced by variable temperature multinuclear FT NMR spectroscopy.The reactions of IV a,b with carbon monoxide are also discussed.