Recent developments in the synthesis and properties of diruthenium tetracarboxylates

The chemistry of diruthenium tetracarboxylates has grown substantially since our initial review in 1998. This update of the literature through 2003 covers the versatile synthetic aspects of the [Ru-2(mu-O2CR)(4)L-n](m+) (n = 1 or 2, m = 0-2) building block, for both mixed-valent Ru-2(II,III) and reduced Ru-2(II,II) cores, in which R can include a wide variety of alkyl, alkoxy, aryl, or metallocenyl groups (including chiral groups) with the axial L group normally being a neutral Lewis base or a halide but could also be a weakly coordinating counterion such as ClO4- or BF4-. The [Ru-2(mu-O2CR)(4)L-n](m+) unit has been linked together, through the judicious choice of axial or equatorial bridging ligands, into a variety of polymeric or network structures that display interesting magnetic, electronic, mesomorphic, occlusion and catalytic properties. The use of biologically relevant and/or hydrophilic R and L groups has also lead to the study of anti-tumor and anti-inflammatory properties. (C) 2004 Elsevier B.V. All rights reserved.