Alkyne trimerization on carbonyl ruthenium clusters. Synthesis and crystal structure of Ru 3(CO) 8(HC 2Bu t) 3

Abstract

The title complex is a minor product of the reaction of Ru 3(CO) 12 or of HRu 3(CO) 9(C 2Bu t) with excess of 3,3-dimethyl-but-1-yne (t-butyl-acetylene); better yields of the product are obtained by reacting η-C 5H 5) 2Ni 2(HC 2Bu t) with Ru 3(CO) 12, probably because of the known ability of nickel in promoting alkyne trimerization. The crystal structure has been determined by X-ray methods. Crystals are triclinic, space group P1 with Z = 2 in a unit cell of dimensions a = 11.665(8) b = 15.292(12), c = 8.877(7) Å, α = 109.45(8) β = 100.68(8), γ = 94.57(7)°. The structure has been solved from diffractometer data by Patterson and Fourier methods and refined by full-matrix least-squares to R = 0.046 for 2999 observed reflections. The complex consists of a bent arrangement of three Ru atoms forming RuRu bonds nearly perpendicular to each other. Eight (six terminal and two bridging) carbonyls coordinate to them and a ligand, deriving from trimerization of the alkyne, forms two σ-bonds with the central Ru atom, giving origin to a metalla-cyclopentadiene ring. The terminal Ru atoms lie on the opposite sides with respect to this ring and are η-bonded to four carbon atoms of it.