Compromising the metal-metal bond in diruthenium(II, III) tetraacetate: Reaction of [Ru-2(mu-O2CMe)(4)(MeOH)(2)](+) with phosphines to form 'Ru(mu-O2CMe)(2)(mu-OMe)(2)Ru' cores

摘要

The anaerobic reactions of mixed-valent [Ru-2(mu-O2CMe)(4)(MeOH)(2)](+) with two sterically demanding phosphines, PCy3 (Cy = cyclohexyl) and PCy2Ph (Ph = phenyl), were carried out and an apparent disproportionation reaction occurred in each case. The two corresponding oxidized, Ru-2(III, III) complexes, [(PCy3) (eta(1)-O2CMe)Ru(mu-OMe)(2)(mu-O2CMe)(2)Ru(eta(1)-O2CMe)(PCy3)]center dot center dot center dot 2MeOH, 1, and [(PPhCy2)(eta(1)-O2CMe)Ru(mu-OMe)(2)(mu-O2CMe)(2)Ru(eta(1)-O2CMe)(PPhCy2)]center dot center dot center dot 2.5MeOH, 3, were found not to contain the typical l-oxo bridge and maintained a single Ru-Ru bond. Both complexes show a rare transoid configured 'Ru(mu-O2CMe)(2)(mu-OMe)(2)Ru' core with the remainder of the Ru coordination sphere containing a monodentate phosphine and a monodentate acetate group. This type of core has only been seen once before, in 2004, by Cotton and coworkers in trans-[Ru-2(mu-OMe)(2)(mu-O2CMe)(2)(eta(1)-DAniF)(4)]Cl-2, 5, (DAniF = N,N'di(p-anisyl)formamidinate). Further reaction of complexes 1 and 3 in methanol led to slow displacement of the monodentate acetate groups for monodentate methoxides as is shown in the structure of complexes [(PCy3)(eta(1)-O2CMe)Ru(mu-OMe)(2)(mu-O2CMe)(2)Ru(eta(1)-OMe)(PCy3)]center dot center dot center dot 3.5MeOH, (2), and [(PPhCy2)(eta(1)-OMe)Ru(mu-OMe)(2)-(mu-O2CMe)(2)Ru(eta(1)-OMe)-(PPhCy2)]center dot 2MeOH, 4, which maintain this rare core. All complexes were characterized by elemental analysis, IR spectroscopy, H-1 NMR and single crystal X-ray diffraction. (C) 2014 Elsevier B.V. All rights reserved.