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 < inf > 2 < /inf > L n < inf > 2 < /inf > 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 < sup > n < /sup > )(CO)(EPh < inf > 3 < /inf > ) < inf > 2 < /inf > ] (where E = P or As) were accomplished by elemental (CHN) analysis, magnetic susceptibility and spectroscopic (ESI-MS, IR, UV-Vis, emission and < sup > 1 < /sup > 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 < sup > n < /sup > ) < sup > 2- < /sup > via regioselective activation of 1-pyrenyl ortho C-H and formation of a distorted octahedral C < inf > 2 < /inf > NSE < inf > 2 < /inf > coordination sphere around the ruthenium(II) centre. [Figure not available: see fulltext.]