Heterooctanuclear Cluster Complex Formation with Phosphine Participation: Synthesis, Structure, and Magnetic Properties of Co₆Ru₂(mp)₁₀(PBuⁿ₃)₆(H₂mp = 2-Mercaptophenol, PBuⁿ₃= Tri-<i>n</i>-butylphosphine)

Abstract

The reaction of CoCl2, RuCl3, Na2(mp), and PBun3 (H2mp = 2-mercaptophenol, PBun3 = tri-n-butylphosphine) in ethanol in the molar ratio of 0.75:0.25:1:1 gave the complex Co6Ru2(mp)10(PBun3)6. The heterooctanuclear complex consists of six cobalt and two ruthenium ions chelated to as well as bridged by the 2-mercaptophenol ligands in a near-dimeric fashion with two μ2-OR groups bridging the two Co3Ru(mp)5(PBun3)3 fragments without a crystallographic center of symmetry. Each fragment is formed by binding two of the Co(mp)2(PBun3) structural units and one Co(mp) species to a central Ru(III) ion through the S donors of the five mp ligands, while the sixth coordination site of the octahedral Ru environment is completed by a phosphine ligand in the axial position. The Co6Ru2 moiety exhibits a zigzag assembly constructed by the μ2-O and μ2-S bridges of the bidentate 2-mercaptophenol ligands in a highly asymmetric fashion. The Co atoms are square pyramidally coordinated with apices that are occupied by the phosphine ligands or an oxygen atom from a mp2- ligand. Variable-temperature magnetic susceptibilities that were measured in the temperature range 300−1.6 K reveal that the spin cluster exhibits weak antiferromagnetic exchange interactions. A quantitative interpretation of the magnetic data was carried out by the irreducible tensor operator approach. Crystal data of the complex are as follows: triclinic space group P1̄, a = 14.931(3) Å, b = 23.195(5) Å, c = 24.259(5) Å, α = 74.91(3)°, β = 74.83(3)°, γ = 78.80(3)°, and Z = 2.