Fe-Rh and Fe-Ir clusters substituted by diphenylacetylene: Synthesis, solid state structure and electrochemical behaviour of [Fe2Ir2(CO)(10)(mu(4):eta(2)-PhCCPh)](2-), [FeIr2(CO)(9)(mu(3):eta(2)-PhCCPh)], and [Fe2Rh(CO)(8)(mu(3):eta(2)-PhCCPh)](-)

摘要

The reaction between [Fe2Ir2(CO)(12)](2) and diphenylacetylene in refluxing CH3CN yields the substituted cluster [Fe2Ir2(CO)(10)(PhC2Ph)](2) (1). In the crystals, the four metal atoms define a butterfly arrangement whose Ir-Ir hinge is parallel to the acetylenic C-2 unit. The neutral triangular cluster [FeIr2(CO)(9)(PhC2Ph)] (2) is obtained by the treatment of 1 with acids at room temperature; in this 48 valence electrons species, the C-C and the Ir-Ir bonds are also parallel, in the mu(3)-eta(2)(parallel to) coordination mode. The cluster [Fe2Rh(CO)(10)] reacts with diphenylacetylene in refluxing THF yielding [Fe2Rh(CO)(8)-(PhC2Ph)] (3). In this 46 C.V.E.'s cluster, the C-2 unit is perpendicular to the Fe-Fe edge, exemplifying the mu(3)-eta(2)(perpendicular to) bonding mode. According to C-13 NMR spectra, the structure of the three clusters is maintained in solution. Electrochemical investigations show that the one-electron oxidation of [Fe2Ir2(CO)(10)(L)](2) (L = 2CO, PhC2Ph) as well as the one-electron reduction of [Fe2Rh(CO)(8)(PhC2Ph)] only generates the respective short lived products. (C) 2008 Elsevier B.V. All rights reserved.