Mixed ligand triangulotriruthenium cluster carbonyls, Ru 3 (CO) 9 (μ-Ph 2 AsCH 2 AsPh 2 )(L) (L = PPh 3 , PCy 2 Ph, P(OCH 3 ) 3 ) and Ru 3 (CO) 8 (μ-Ph 2 AsCH 2 AsPh 2 )(μ-Ph 2 PCH 2 PPh 2 ) were synthesised and characterised by microanalysis, IR, 1 H, 1 3 C and 3 1 P NMR spectrometry. Single crystal X-ray structure determination of Ru 3 (CO) 9 (μ-Ph 2 AsCH 2 AsPh 2 )(PCy 2 Ph) and Ru 3 (CO) 8 (μ-Ph 2 AsCH 2 AsPh 2 )(μ-Ph 2 PCH 2 PPh 2 ) are reported. In both the clusters, the triruthenium framework is planar. In Ru 3 (CO) 9 (μ-Ph 2 AsCH 2 AsPh 2 ) (PCy 2 Ph), the monodentate phosphine occupies an equatorial position for steric reasons. The effect of trisubstitution is explicit in the highly significant differences observed in Ru--Ru distances (2.8301(6), 2.8653(7) and 2.8873(7) 9) in the present compound compared to Ru 3 (CO) 1 0 (μ-Ph 2 AsCH 2 AsPh 2 ). The observed Ru--As distances are 2.4508(7) and 2.4331(7) 9 respectively and the Ru--P distance is 2.362(1) 9. In the case of Ru 3 (CO) 8 (μ-Ph 2 AsCH 2 AsPh 2 )(μ-Ph 2 PCH 2 PPh 2 ), 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) 9). However, positional disorder is associated with As and P atoms. Other bond parameters are normal.