Syntheses and structures of some coordinatively saturated and unsaturated diruthenium carbonyl complexes

Abstract

Reaction of [Ru-2(CO)(4)(mu-DPPM)(2)(mu-OAc)][PF6] (1) with Et3O+BF4- in MeCN produced coordinatively saturated [Ru-2(mu-CO)(2)(mu-DPPM)(2)(MeCN)(4)][BF4](2) (2). Upon addition of an excess amount of a uni-negative anion X- to a solution of 2 in MeCN, a series of neutral, coordinatively unsaturated adducts[Ru-2(mu-CO)(2)(mu-DPPM)(2)X-2] (X- = Cl-, 3a; Br-, 3b; I-, 3c, SH-, 3d; Stol(-), 3e; S'Pr-, 3f) were readily formed. The reaction of 3a with trimethylamine N-oxide dihydrate produced two isomeric products of [Ru-2(CO)(2)(mu-DPPM)(2)Cl-2(mu-H)(mu-OH)] at a ratio of 4a-4b = 2.25. Treatment of 3b and 3c with dimethyl acetylenedicarboxylate produced [Ru-2(mu-CO)(mu-DPPM)(2)(mu-MeO2CCCCO2Me)X-2] (X = Br, 5a, 1, 5b), whereas treating of 3e and 3f with I-2, yielded [Ru-2(CO)(2)(mu-DPPM)(2)I-2(mu-I)(mu-SR)] (R = tol, 6a; 'Pr, 6b). The structures of 2, 3a, 3c, 3e, 4b, 5a and 6a were determined by X-ray crystallography. The observed Ru-Ru distances are compared and explained in terms of both electronic and steric effects by considering the multiple metal-ligand (M-X) bonding interactions and Alvarez's structural parameters including M-M-X pyramidal angles and the X-M-M-X torsional angles. (C) 2002 Elsevier Science B.V. All rights reserved.