Reaction of ruthenium carbonyl chloride with iridium tetracarbonyl anion. Synthesis, crystal structure and characterisation of [Ru 2Ir 2H(CO) 12Cl]: a heterometallic tetranuclear butterfly cluster with chloride bridge

Abstract

Reaction between [Ru 2(CO) 6Cl 4] and Na[Ir(CO) 4] in tetrahydrofuran (THF) yielded [Ru 2Ir 2H(CO) 12Cl], a new iridium–ruthenium mixed-metal cluster of possible catalytic interest. The cluster was characterised by 1H-NMR and infrared spectroscopy and by single-crystal X-ray structure analysis. [Ru 2Ir 2H(CO) 12Cl] exhibits a butterfly arrangement of metal atoms, with three terminal carbonyls on each metal atom, chloride ligand in the bridging position, and hydride ligand at the Ir–Ir edge. The trinuclear ruthenium cluster [Ru 3( μ-Cl) 2(CO) 8(PPhMe 2) 2] was synthesised by reaction of [Ru 2(CO) 6Cl 4] with K[Ir(CO) 4] in THF, followed by ligand substitution with [PPhMe 2] in CH 2Cl 2 at ambient temperature. Determination of the structure by X-ray diffraction showed it to consist of an open trinuclear unit involving two metal–metal bonds. The open edge of the metal framework is supported by two symmetric bridging chloride ligands. Both phosphorus ligands are cis to the chlorine atoms and trans to the unique ruthenium atom.