UNUSUAL IRON-IRON AND RUTHENIUM-RUTHENIUM SINGLE BONDS DOUBLY BRIDGED BY 2 CU(PR3) FRAGMENTS - SYNTHESES OF IRON COPPER, IRON SILVER, AND RUTHENIUM COPPER HETEROMETALLIC COMPLEXES AND STRUCTURES OF M2(CO)8(MU-CUPCY3)2 (M = FE, RU), [PPH4][FE2(CO)8(MU-CUPCY3)], AND [PPH4]2([FE2(CO)8]2[MU-4-ETA-2-CU2(CY2PCH2CH2PCY2)])

Heterometallic tetranuclear clusters M2(CO)8(mu-M'PCy3)2 (M = Fe, M' = Cu (1); M = Fe, M' = Ag(2); M = Ru, M' = Cu (3)), trinuclear clusters X[M2(CO)8(mu-M'PCy3)] (X = Na, M = Fe, M' = Cu (4a); X = PPh4, M = Fe, M' = Cu (4b); X = PPh4, M = Fe, M'= Ag (5); X = PPh4, M = Ru, M' = Cu (6)), and the hexanuclear complex [PPh4]2{[Fe2(CO)8]2[mu-4-eta2-Cu2 (Cy2PCH2CH2PCy2)]} (7) are synthesized from reactions of the transition-metal carbonylates [M2(CO)8]2- (M = Fe, Ru) with mixtures of [Cu(CH3CN)4][PF6] or AgBF4 and the phosphine ligand tricyclohexlphosphine (PCy3) or 1,2-bis(dicyclohexylphosphino)ethane (Cy2PCH2CH2PCy2). The molecular structures of 1,3, 4b.0.5THF, and 7 were determined from single-crystal X-ray data. The structures of 1 and 3 are without precedent in that they contain Fe-Fe and Ru-Ru single bonds doubly bridged by two Cu(PCy3) fragments. The four-metal cores are of the butterfly type with dihedral angles of about 150-degrees. Futhermore, two Cu(PCy3) fragments bridge the M-M bond in an asymmetric fashion, which might be caused by a second-order Jahn-Teller effect. In 4b, the Fe-Fe bond in the Fe2(CO)8 unit is bridged by one Cu(PCy3) fragment. In 7, two Fe2(CO)8 units are connected by a CuP(Cy2)CH2CH2(Cy2)PCu moiety. Crystal data: Fe2(CO)8(mu-CuPCy3)2 (1), monoclinic, space group P2(1)/c, a = 11.042 (2) angstrom, b = 17.321 (3) angstrom, c = 24.824 (6) angstrom, beta = 92.32 (2)-degrees, Z = 4, and R = 0.030; Ru2(CO)8(mu-CuPCy3)2 (3), monoclinic, space group P2(1)/c, alpha = 11.013 (2) angstrom, b = 17.370 (3) angstrom, c = 25.169 (4) angstrom, beta = 92.53 (1)-degrees, Z = 4, and R = 0.022; [PPh4][Fe2(CO)8(mu-CuPCy3)].0.5THF (4b.05THF) triclinic, space group P1BAR, a = 10.717 (2) angstrom, b = 11.703 (2) angstrom, c = 24.130 (7) angstrom, alpha = 90.62 (2)-degrees, beta = 92.32 (2)-degrees, gamma = 115.53 (1)-degrees, Z = 2, and R = 0.075; [PPh4]2{[Fe2(CO)8]2[mu-4-eta-2-Cu2(Cy2PCH2CH2PCy2)]} (7): triclinic, space group P1BAR, alpha = 10.810 (1) angstrom, b = 11.976 (1) angstrom, c = 18.254 (2) angstrom, alpha = 81.11 (1)-degrees, beta = 82.32 (1)-degrees, gamma = 71.40 (1)-degrees, Z = 1, and R = 0.032.