Ruthenium carbonyl cluster complexes with oxygen ligands. Reactions between Ru₃(CO)₁₂ and 4-methoxyphenol or 2-naphthol. Crystal structure of Ru₄(μ₃-OC₆H₄OMe-4)₂(μ-Cl)(μ-OC₆H₄OMe-4)(CO)₁₀, an unusual mixed-valence cluster complex

Abstract

The reaction between 4-methoxyphenol and Ru3(CO)12 in cyclohexane has been investigated and found to afford a hexaruthenium 'raft' cluster Ru6(μ-H)2(μ5-η7-OC6H3OMe-4)(CO)16 (3a), together with tetraruthenium clusters incorporating three (Ru4(μ3-OC6H4OMe-4)2(μ-Cl)(μ-OC6H4OMe-4)(CO)10 (3b)) or four (Ru4(μ3-OC6H4OMe-4)2(μ-OC6H4OMe-4)2(CO)10 (3c)) aryloxo ligands; similarly, reaction of Ru3(CO)12 with 2-naphthol afforded the analogous Ru6(μ-H)2(μ5-η7-OC10H6)(CO)16 (4a), Ru4(μ3-OC10H7)2(μ-Cl)(μ-OC10H7)(CO)10 (4b) and Ru4(μ3-OC10H7)2(μ-OC10H7)2(CO)10 (4c). The source of chloride in 3b and 4b is believed to be carbon tetrachloride contaminant in the cyclohexane. An X-ray diffraction study reveals that 3b contains an Ru3(CO)8 unit linked to an Ru(CO)2 moiety by two asymmetric triply-bridging and one asymmetric doubly-bridging 4-methoxyphenoxo ligands, and an asymmetric doubly-bridging chloro ligand; this interaction is strongly suggestive of a higher oxidation state ruthenium linked to a trinuclear cluster of formally zero oxidation state. The dynamic 13C NMR spectra of 4c have been recorded, and are consistent with restricted rotation about the ArO linkage of the μ2-coordinated naphthoxo ligands at low temperature. Show more