Polymeric, molecular, and cation/anion arrangements in chloro-, bromo-, and iododiruthenium(II,III) carboxylate compounds

The synthesis and characterization of the anhydrous compounds [Ru2X(mu-O2CR)(4)] [R = CH2CH2OPh, X = Cl (1a), Br (2a), I (3a); R = CMePh2, X = Br (5a), I (6a)] and of the solvated complexes [Ru2X(mu-O2CR)(4)(H2O)] [R = CH2CH2OPh, X = Cl (1b), I (3b); R = CMePh2, X = Cl (4b), Br (5b), I (6b)] are described. Thermogravimetric analyses have been used to confirm the anhydrous or solvated natures of the complexes. The crystal structures of 1b.2MeOH, 3b.0.5H(2)O, and 4b have been investigated by X-ray diffraction and none of them shows the usual polymeric arrangement reported for tetracarboxylatodiruthenium(II,III) compounds. The structure of 3b.0.5H(2)O consists of cationic and anionic units, [Ru-2(mu-O2CCH2CH2OPh)(4)(H2O)(2)][Ru2I2(mu-O2CCH2CH2OPh)(4)], and represents the first reported crystal structure of a tetracarboxylato(iodo)diruthenium(II,III) derivative. The structures 1b.2MeOH and 4b each show the presence of discrete dinuclear molecules. The crystal structure of [Ru2Cl(mu-O2CCMePh2)(4)(H2O)] demonstrates that diruthenium compounds with the same halide and carboxylate ligands may adopt polymeric or discrete molecular dispositions. Magnetic susceptibility measurements of the complexes in the 2-300 K range have been carried out. Complex 2a shows a strong antiferromagnetic coupling, consistent with the existence of linear chains in the solid state. The complexes [Ru2X(mu-O2CR)(4)(H2O)] show weak through-space antiferromagnetic coupling, in accordance with non-polymeric structures. The magnetic behaviour of la, 3a, 5a, and 6a suggests a mixture of arrangements. ((C) Wiley-VCH Verlag GmbH & Co. KGaA, 69451 Weinheim, Germany, 2003).