The preparation and x-ray structural characterization of dinuclear chromium, molybdenum, ruthenium, rhodium, and osmium complexes

Abstract

Eleven new dimeric complexes containing metal-metal bonds have been prepared and structurally characterized by X-ray crystallography. Seven are of the type M(,2)(O(,2)CR)(,4) (M = Cr, Mo, Rh; R = CH(,3), 2-biphenyl, CPh(,3), 1-adamantyl); the remaining four formulated as M(,2)(2-oxopyridinato)(,4)ClX (M = Ru, Os; X = Cl, 2-hydroxypyridine). Cr(,2)(O(,2)Cbiph)(,4) is prepared by the reaction of 2-biphenylcarboxylic acid(HO(,2)Cbiph) with either Cr(,2)(O(,2)CCH(,3))(,4) in THF or with CrCp(,2) (Cp=C(,5)H(,5)) in toluene, giving, respectively, Cr(,2)(O(,2)Cbiph)(,4)(THF)(,2) with a Cr-Cr bond distance of 2.316(3)(ANGSTROM) and {Cr(,2)(O(,2)Cbiph)(,4)}(,2)(.)4C(,7)H(,8), a dimer of dimers, with a Cr-Cr distance of 2.348(2)(ANGSTROM). Reaction of Mo(,2)(O(,2)CCH(,3))(,4) with HO(,2)Cbiph gave the expected Mo(,2)(O(,2)Cbiph)(,4) with a Mo-Mo distance of 2.082(1)(ANGSTROM), the first dimolybdenum tetracarboxylate to be totally isolated from axial coordination. Crystallization of Rh(,2)(O(,2)CCH(,3))(,4) from a 1:1 acetonitrile/toluene mixture gave Rh(,2)(O(,2)CCH(,3))(,4)(CH(,3)CN)(,2) with a Rh-Rh distance of 2.384(1)(ANGSTROM). Reaction of Rh(,2)(O(,2)CCH(,3))(,4) with HO(,2)Cbiph, triphenylacetic acid, and 1-adamantanecarboxylic acid gave the compounds Rh(,2)(O(,2)Cbiph)(,4)(CH(,3)CN)(,2)(.)3C(,6)H(,6) with a Rh-Rh distance of 2.396(1)(ANGSTROM); Rh(,2)(O(,2)CCH(,3))(,2)(O(,2)CCPh(,3))(,2)(CH(,3)CN)(,2)(.)C(,7)H(,8) with a Rh-Rh distance of 2.388(2)(ANGSTROM); and Rh(,2){1-O(,2)Cadamantyl}(,4)(HOCH(,3))(,2). 5HOCH(,3) with a Rh-Rh distance of 2.371(2)(ANGSTROM). Reaction of 2-hydroxypyridine (Hhp) with either Ru(,2)(O(,2)CCH(,3))(,4)Cl or "RuCl(,3)(.)3H(,2)O" gives, respectively, Ru(,2)(hp)(,4)Cl with a Ru-Ru distance of 2.250(2)(ANGSTROM) and Ru(,2)(hp)(,4)(Hhp)Cl with a Ru-Ru distance of 2.283(1)(ANGSTROM). Reaction of Hhp with OsCl(,3) in ethanol yielded the compound Os(,2)(hp)(,4)Cl(,2), which upon crystallization from a 1:1 mixture of ether/dichloromethane gives Os(,2)(hp)(,4)Cl(,2)(.)Et(,2)) with a Os-Os bond distance of 2.344(2)(ANGSTROM). Recrystallization of this compound from acetonitrile gives Os(,2)(hp)(,4)Cl(,2)(.)2CH(,3)CN with a Os-Os distance of 2.357(1)(ANGSTROM). This compound is formulated as being the first example of an Os-Os triple bond.