Synthesis and spectral studies on Ru3(CO)12-n(μ-Ph2AsCH2AsPh2)(L) (n = 3, L = PPh3, PCy2Ph, P(OCH3)3);: n = 4, L = Ph2PCH2PPh2):: crystal and molecular structures of Ru3(CO)9(μ-Ph2AsCH2AsPh2)(PCy2Ph) and Ru3(CO)8(μ-Ph2AsCH2AsPh2)(μ-Ph2PCH2PPh2)

Mixed ligand triangulotriruthenium cluster carbonyls, Ru-3(CO)(9)(mu-Ph2AsCH2AsPh2) (L) (L = PPh3, PCy2Ph P(OCH3)(3)) and Ru-3(CO)(8)(mu-Ph2AsCH2AsPh2) (mu-Ph2PCH2PPh2) were synthesised and characterised by microanalysis, IR, H-1,C-13 and P-31 NMR spectrometry. Single crystal X-ray structure determination of Ru-3(CO)(9)(mu-Ph2AsCH2AsPh2) (PCy2Ph) and Ru-3(CO)(8)(mu-Ph2AsCH2AsPh2) (mu-Ph2PCH2PPh2) are reported. In both the clusters, the triruthenium framework is planar. In Ru-3(CO)(9)(mu-Ph2AsCH2AsPh2) (PCy2Ph), the monodentate phosphine occupies an equatorial position for steric reasons. The effect of tri-substitution is explicit in the highly significant differences observed in Ru-Ru distances (2.8301(6), 2.8653(7) and 2.8873(7) Angstrom) in the present compound compared to Ru-3(CO)(10)(mu-Ph2AsCH2AsPh2). The observed Ru-As distances are 2.4508(7) and 2.4331(7) Angstrom respectively and the Ru-P distance is 2.362(1) Angstrom. In the case of Ru-3(CO)(8)(mu-Ph2AsCH2AsPh2) (mu-Ph2PCH2PPh2), the chelating ligands occupy four equatorial positions. Two of the Ru-Ru distances are similar in length (2.848(2), 2.850(2) and 2.828(2) Angstrom). However, positional disorder is associated with As and P atoms. Other bond parameters are normal. (C) 1998 Elsevier Science Ltd. All rights reserved.