LIGAND-EXCHANGE PHOTOCHEMISTRY OF M-2(CO)(4)(MU-ETA(5),ETA(5)-C5H4CH2C5H4) (M = FE OR RU) AND THERMAL ACETYLENE EXCHANGE OF ETA(1)-(C6H5)(2)C-2](MU-ETA(5),ETA(5)-C5H4CH2C5H4) - THE MOLECULAR-STRUCTURES OF U-CO)[MU-P(C6H5)(2)](MU-ETA(5),ETA(5)-C5H4CH2C5H4) AND (3)-C6H5C=C(C6H5)O]-(MU-ETA(5),ETA(5)-C5H4CH2C5H4)

Photolysis of Fe-2(CO)(4)(mu-eta(5),eta(5)-C5H4CH2C5H4) in the presenc e of phosphines or phosphites results in the formation of simple carbo nyl substitution products Fe-2(CO)(mu-CO)(2)L(mu-eta(5),eta(5)-C5H4CH2 C5H4) or Fe-2(mu-CO)(2)L-2(mu-eta(5),eta(5)-C5H4CH2C5H4). Acetylenes r eact photochemically with the diiron compound to give vinylketone-brid ged derivatives of the form Fe-2(CO)(mu-CO)[mu-eta(1):eta(3)- RC=C(R)C O](mu-eta(5),eta(5)-C5H4CH2C5H4), where R = CH3O2C and C6H5. Reaction of Ru-2(CO)(4)(mu-eta(5),eta(5)-C5H4CH2C5H4) With triphenylphosphine u nder photochemical conditions resulted in loss of two carbon monoxide ligands and P-C insertion by ruthenium to yield -CO)[mu-P(C6H5)(2)](mu -eta(5),eta(5)-C5H4CH2C5H4). Photolysis of Ru-2(CO)(4)(mu-eta(5),eta(5 )-C5H4CH2C5H4) With diphenylacetylene gave the previously reported eta (1)-(C6H5)(2)C-2](mu-eta(5),eta(5)-C5H4CH2C5H4) and an air oxidation p roduct, (3)-C6H5C=C(C6H5)O](mu-eta(5),eta(5)-C5H4CH2C5H4). The dipheny lacetylene derivative underwent acetylene exchange, but did not underg o exchange with triphenylphosphine. All compounds have been characteri zed by spectroscopic methods, elemental analysis and/or mass spectrosc opy. The molecular structures of two ruthenium compounds were determin ed by X-ray crystallography. -CO)[mu-P(C6H5)(2)](mu-eta(5),eta(5)-C5H4 CH2C5H4): monoclinic, P2(1)/c, a = 13.902(3) Angstrom, b = 13.283(3) A ngstrom, c = 14.426(4) Angstrom, beta = 101.62(2)degrees, V = 2609(1) Angstrom(3), z = 4, R(F)= 3.98%. RU2(CO)(mu-CO)[mu-eta(1):eta(3)- C6H5 C=C(C6H5)O](mu-eta(5),eta(5)-C5H4CH2C5H4): orthorhombic, Pccn, a = 15. 000(4) Angstrom, b = 15.662(4) Angstrom, c = 19.053(4) Angstrom, V = 4 476(2) Angstrom(3), z = 8, R(F)= 3.05%. (C) 1997 Elsevier Science S.A.