Study of new mononuclear platinum group metal complexes containing η5 and η6 - Carbocyclic ligands and nitrogen based derivatives and formation of helices due to N-H•••Cl interactions

A quite general approach for the preparation of eta(5)- and eta(6)-cyclichydrocarbon platinum group metal complexes is reported. The dinuclear arene ruthenium complexes [(eta(6)-arene)Ru(l.t-CI)C112 (arene = C6H6, C10H14 and C6Me6) and eta(5)-pentamethylcyclopentadienyl rhodium and iridium complexes [(eta(5)-C5Me5)M(mu-Cl)Cl](2) (M = Rh and Ir) reacts with two equivalents of the ligands 2-chloro-3-(pyrazolyl)quinoxaline (L-1) and di-(2-pyridyl)amine (12) in presence of NH4PF6 to afford the corresponding mononuclear complexes of the type [(eta(6)-arene)Ru(L-1)Cl]PF6 {arene = C6H6 (1), C10H14 (2) and C6Me6 (3)), [eta(6)-arene)Ru(L-2)Cl]PF6 farene = C6H6 (4), C10H14 (5) and C6Me6 (6)), and [eta(5)-C5Me5)M(L-1)Cl]PF6 (M = Rh (7), Ir (8)) and [eta(5)-C5Me5)M(L-2)Cl]PF6 = Rh (9), Ir (10)). However the mononuclear eta(5)-cyclopentadienyl analogues such as [(eta(5)-C5H5)Ru(PPh3)(2)Cl], [(eta(5)-C5H5)Os(PPh3)(2)Br], [(eta(5)-C5Me5)Ru(PPh3)(2)Cl] and [(eta(5)-C9H7)Ru(PPh3)(2)Cl] complexes react in presence of one equivalent of ligands 2-chloro-3-(pyrazolyl)quinoxaline (L-1) and di-(2-pyridyl)amine (L-2) and one equivalent of NH4PF6 in methanol yielded mononuclear complexes [(eta(6)-C5H5)Ru(PPh3)(L-1)]PF6 (11), [eta(5)-C5H5)Os(PPh3)(L-1)]PF6 (12), [(eta(6)-C5Me5)Ru(PPh3)(L-1)]PF6 (13) and [(eta(5)-C9H2)Ru(PPh3)(L-1)]PF6 (14) and [(eta(5)-C5H5)Ru(PPh3)(L-2)]PF6 (15), [(eta(5)-C5H5)Os(PPh3)(L-2)]PF6 (16), [(eta(5)-C5Me5)Ru(PPh3)(L-2)]PF6 (17) and [(eta(5)-C9H2)Ru(PPh3)(L-2)]PF6 (18) respectively. These compounds have been systematically characterized by IR, NMR and mass spectrometry. The molecular structures of 2, 4 and 15 have been established by single crystal X-ray diffraction study and some of the representative complexes have also been studied by UV-visible spectroscopy. The crystal packing diagram of complex 4 reveals that the cation [(eta(6)-C6H6)Ru(L-2)Cl](+) is engaged in non-covalent interaction. This compound gives rise to a 1D helical architecture along the 'a' axis via intermolecular N H center dot center dot center dot Cl hydrogen bonds. (C) 2010 Elsevier BA/. All rights reserved.