Systematic synthesis, solution structural characterization of the square-pyramidal clusters MIr4(CO)7(.mu.-CO)2L(.eta.5-C5Me5)(.mu.4-PPh) (M = Rh, Ir; L = CO, PPh3), and x-ray structural determination of the iridium derivatives

Abstract

The pentanuclear clusters MIr{sub 4}(CO){sub 9}L({eta}{sup 5}-C{sub 5}Me{sub 5})({mu}{sub 4}-PPh) (L = CO, M = Rh (3), Ir (4) and L = PPh{sub 2}Me or PPh{sub 3}, M = Rh (3a) or (3b), Ir (4a) or (4b)) are synthesized in good yields by the reactions of Ir{sub 4}(CO){sub 11}(PPhH{sub 2}) and Ir{sub 4}(CO){sub 10}(PPhH{sub 2})L (L = PPh{sub 2}Me or PPh{sub 3}), respectively, in acetonitrile with (M-({eta}{sup 5}-C{sub 5}Me{sub 5})(NCMe){sub 3})(SbF{sub 6}){sub 2} (M = Rh, Ir) in the presence of 1,8-diazabicyclo(5.4.0)undec-7-ene (DBU). All compounds are characterized by fast-atom bombardment mass spectrometry and a combination of {sup 1}H, {sup 13}C and {sup 31}P NMR. Crystal data for 4: space group P{bar 1}, a = 14.511 (5), b = 15.366 (8), c = 13.962 (2) {angstrom}, {alpha} = 89.99 (3), {beta} = 93.94 (2), {gamma} = 86.15 (3){degree}, Z = 4. Crystal data for 4b: space group P2{sub 1}/a, a = 17.949 (2), b = 9.998 (4), c = 25.606 (5) {angstrom}, {beta} = 108.94 (1){degree}, Z = 4. The solution structures of 3, 4, 3b, and 4b were determined by low-temperature {sup 13}C NMR and are fully consistent with the solid-state structures.