Heteronuclear Dirhodium-Gold Anionic Complexes: Polymeric Chains and Discrete Units

In this article, we report on the synthesis and characterization of the tetracarboxylatodirhodium(II) complexes [Rh(2)(μ–O(2)CCH(2)OMe)(4)(THF)(2)] (1) and [Rh(2)(μ–O(2)CC(6)H(4)–p–CMe(3))(4)(OH(2))(2)] (2) by metathesis reaction of [Rh(2)(μ–O(2)CMe)(4)] with the corresponding ligand acting also as the reaction solvent. The reaction of the corresponding tetracarboxylato precursor, [Rh(2)(μ–O(2)CR)(4)], with PPh(4)[Au(CN)(2)] at room temperature, yielded the one-dimensional polymers (PPh(4))(n)[Rh(2)(μ–O(2)CR)(4)Au(CN)(2)](n) (R = Me (3), CH(2)OMe (4), CH(2)OEt (5)) and the non-polymeric compounds (PPh(4))(2){Rh(2)(μ–O(2)CR)(4)[Au(CN)(2)](2)} (R = CMe(3) (6), C(6)H(4)–p–CMe(3) (7)). The structural characterization of 1, 3·2CH(2)Cl(2), 4·3CH(2)Cl(2), 5, 6, and 7·2OCMe(2) is also provided with a detailed description of their crystal structures and intermolecular interactions. The polymeric compounds 3·2CH(2)Cl(2), 4·3CH(2)Cl(2), and 5 show wavy chains with Rh–Au–Rh and Rh–N–C angles in the ranges 177.18°–178.69° and 163.0°–170.4°, respectively. A comparative study with related rhodium-silver complexes previously reported indicates no significant influence of the gold or silver atoms in the solid-state arrangement of these kinds of complexes.