DIRUTHENIUM AND DIOSMIUM TETRACARBOXYLATES - SYNTHESIS, PHYSICAL-PROPERTIES AND APPLICATIONS

Dimetal tetracarboxylates, [M-2(O2CR)(4)](n), have received much cover age in the literature. The metals include Cr, Mo, W, Tc, Re, Ru, Os, C o, Rh, Ir, Ni and Cu with n ranging from -2 to +4 (0 to +2 being most common). Diruthenium and diosmium tetracarboxylates form two of the yo unger families of these ubiquitous compounds and are known to exist as homovalent Ru,(II,II) and Os,(III,III) and mixed-valent Ru,(II,III) a nd Os,(II,III) species. This paper will provide a comprehensive review of these complexes and include such things as their discovery, synthe sis and crystal structures; electronic, vibrational (IR and Raman), ES R and photoelectron spectroscopy; magnetic susceptibility; electrochem istry; kinetics; calorimetry; theoretical calculations such as SCF-X a lpha-SW and CASSCF; and more recent studies of their mesomorphic behav iour and biological and catalytic applications. The ruthenium compound s, in particular, have shown a potential application as liquid crystal s. Current work (including this author's) is also focused on the devel opment of linear chains involving these metal carboxylate units and bi dentate bridges with the view to developing ferromagnetic materials an d conductive polymers. There have been no previous reviews on rutheniu m (and osmium) carboxylates per se. Cotton and Walton give them some c overage in the context of metal-metal bonds in Multiple Bonds Between Metal Atoms (2nd ed., 1993) however the direct coverage of Ru-2(O2CR)( 4) and Os-2(O2CR)(4) type complexes is cursory and dispersed throughou t the book. As well, the coverage is only comprehensive through Decemb er 1990 with some references from 1991. The current review will be com plete through to mid-1997. (C) 1998 Elsevier Science S.A.