HEXANUCLEAR ARENE CLUSTERS OF RUTHENIUM

The hexanuclear cluster (Ru6C(CO)14(eta6-arene)] 1 (arene = C6H6, C6H5 Me, C6H4Me2-1,3 or C6H3Me3-1,3,5) reacts with Me3NO-CH2Cl2 in the pres ence of cyclohexa-1,3-diene or cyclohexa-1,4-diene to yield compound [ Ru6C(CO)12(eta6-arene)(mu-eta2:eta2-C6H8)] 2 in which the diene spans one metal edge of the octahedral cluster unit. Further treatment of 2 with Me3NO-CH2Cl2 affords the bis(arene) derivative [Ru6C(CO)11(eta6-a rene)(C6H6)]. Onthe basisof spectroscopic data and single-crystal X-ra ydata itappears that these bis(arene) derivatives exist in two isomeri c forms, viz. [Ru6C(CO)11(eta6-arene)(mu-eta2:eta2:eta2-C6H6)] 3 and ( Ru6C(CO)11(eta6-arene)(eta6-C6H6)] 4. Evidence that compound 3 isforme d initially,followed by isomerisation to 4 is presented. The structure s of [Ru6C(CO)11(eta6-C6H5Me)(mu3-eta2:eta2:eta2-C6H6)] 3b and (CO)11( eta6-C6H4Me2-1,3)(mu3-eta2:eta2:eta2-C6H6)] 3c have been determined by single-crystal X-ray diffraction. Compound 3b is orthorhombic. space group Pnma, a = 9.035(5), b = 14.796(2), c = 20.534(4) angstrom, Z = 4 , 1770 unique observed reflections [I > 2sigma(I)], R = 0.020; 3c is m onoclinic, space group P2(1)/n, a = 18.27(2), b = 9.729(2), c = 34.39( 3) angstrom, beta = 94.94(6)-degrees, Z = 8, 7833 unique observed refl ections [I > 2.0sigma(I)], R = 0.058, R' = 0.062.