Cyclometallated ruthenium(II) carbonyl complexes with 1-pyrenaldehyde 4-R-3-thiosemicarbazones: Regioselective ruthenation of the 1-pyrenyl group

Abstract

A facile method for the synthesis of a series of cyclometallated ruthenium(II) carbonyl complexes with 1-pyrenaldehyde 4-R-3-thiosemicarbazones (H 2 L n 2 L n where the two H's represent the dissociable thioamide and pyrenyl protons; R = H, Me and Ph) has been described. The characterization of the complexes having the general molecular formula trans-[Ru(L n)(CO)(EPh 3) 2 ] (where E = P or As) were accomplished by elemental (CHN) analysis, magnetic susceptibility and spectroscopic (ESI-MS, IR, UV-Vis, emission and 1 H-NMR) measurements. Electronic spectra of the complexes display multiple strong absorptions in the range 440-224 nm due to intraligand transitions. All the complexes exhibit emission bands that are characteristic of ligand centred emissive states. X-ray diffraction studies with representative complexes reveal a pincer-like 5,5-membered fused chelate rings forming CNS coordination mode of the thiosemicarbazonate ligand (L n) 2- via regioselective activation of 1-pyrenyl ortho C-H and formation of a distorted octahedral C 2 NSE 2 coordination sphere around the ruthenium(II) centre. [Figure not available: see fulltext.]