ARYLOXIDE AND ALKOXIDE DERIVATIVES OF METAL-CLUSTERS - SYNTHESES, STRUCTURES, AND REACTIVITIES OF THE MU-OXO-BRIDGED TRIRUTHENIUM CLUSTERS RU3(CO)8(MU-ETA-2-OC6H4CL)2 AND RU3(CO)8(MU-ETA-2-OCH2C5H4N)2

The halide-stabilized phenol derivatives of triruthenium carbonyl Ru3(CO)8(mu-eta2-OC6H4X)2 (X = F, Cl, Br) have been synthesized via the reaction of RU3(CO)12 with the corresponding phenol (o-XC6H4OH) and anhydrous Me3NO. The complex where X = Cl(I) has been characterized both in solution by FTIR and H-1/C-13 NMR spectroscopies and in the solid-state by X-ray crystallography. The o-OC6H4Cl- ligands serve as five-electron donor groups which bridge an edge of the triruthenium framework, with the bridged Ru ... Ru separation being significantly longer (3.042(1) angstrom) than the other two Ru-Ru bond distances, which average 2.738[1] angstrom. The coordination spheres of the ruthenium centers, which arc mu-oxygen atom bridged, arc completed by interactions with the chloride substituents on the phenol ligands. The unique ruthenium atom has a Ru(CO)4 structure similar to that of the parent dodecacarbonyl cluster. Complex 1 is shown to reversibly react with carbon monoxide to disrupt the Ru ... Cl interaction to afford unstable Ru3(CO)8+n(mu-OC6H4Cl)2 (n = 1, 2) species. Similarly, complex 1 reacts sequentially with a variety of donor ligands (L) to provide more stable Ru3(CO)8L2(mu-OC6H4X)2 derivatives. A stable prototype of one such complex, Ru3(CO)8(mu-eta2-OCH2C5H4N)2 (12), was prepared from Ru3(CO)12 and pyridinecarbinol in the presence of anhydrous Me3NO. This derivative was characterized in the solid state by X-ray crystallography. It was shown to possess two ruthenium metal centers (nonbonded at 3.024(1) angstrom) bridged by two alkoxide mu-O atoms, with each pyridine substituent further being bonded to a ruthenium atom. The bonded Ru-Ru distances in the triangular cluster averaged 2.783[1] angstrom. Crystal data for 1: orthorhombic space group Pbca, a = 18.676(4) angstrom, b = 9.106(2) angstrom, c = 28.496(6) angstrom, Z = 8, R = 5.07%. Crystal data for 12: space group P2(1)/c, a = 12.305(3) angstrom, b = 10.331(2) angstrom, c = 18.489(4) angstrom, beta = 90.67(2)-degrees, Z = 4, R = 3.08%.