Ru2(CO)4{OOC(CH2) n CH3}2L2 sawhorse-type complexes containing μ2-η2-carboxylato ligands derived from saturated fatty acids

Abstract

The thermal reaction of Ru3(CO)12 with the saturated fatty acids (heptanoic, nonanoic, decanoic, tridecanoic, tetradecanoic, heptadecanoic, octadecanoic) in refluxing tetrahydrofuran, followed by addition of triphenylphosphine (PPh3) or pyridine (C5H5N), gives the dinuclear complexes Ru2(CO)4{OOC(CH2)nCH3}2L2 (1: n = 5, 2: n = 7, 3: n = 8, 4: n = 11, 5: n = 12, 6: n = 15, 7: n = 16; a: L = NC5H5, b: L = PPh3). The single crystal structure analysis of 1b, 2a, 3a, 4a and 5a reveals a dinuclear Ru2(CO)4 sawhorse structure, the diruthenium backbone being bridged by the carboxylato ligands, while the two L ligands occupy the axial positions at the ruthenium atoms. In 2a, π-π stacking interactions between adjacent pyridyl units of symmetry related molecules prevail, while in the longer alkyl chain derivatives 3a, 4a and 5a, additional van der Waals and electrostatic interactions between the alkyl chains take place as well in the packing arrangement of the molecules, thus giving rise to layers of parallel alkyl chains in the crystal.