Study of half-sandwich mono and dinuclear complexes of platinum group metals containing pyrazolyl pyridine analogues: Synthesis and spectral characterization

Abstract

The chelating ligands 3-chloro-6-(3-pyridyl-1-pyrazolyl)pyridazine (pp-Cl) and 3,6-bis(3-pyridyl- 1-pyrazolyl)pyridazine (bppp), were prepared by the condensation of pyridylpyrazole and 3,6-dichloropyridazine. The mononuclear complexes [(η 6-arene)Ru(pp-Cl)Cl] + {η 6-arene = C6H6 (1); p-iPrC6H4Me (2)}, [(η 5-C5Me5)M(pp-Cl)] + {M = Rh (3); Ir (4)}, [(η 6-arene)Ru(bppp)Cl] + {η 6-arene = C6H6 (5); p-iPrC6H4Me (6)}, [(η 5-C5Me5)M(bppp)] + {M =Rh (7); Ir (8)} as well as the binuclear complexes [{(η 6-arene)RuCl}2(bppp)]2 + {η 6 -arene =C6H6 (9); p-iPrC6H4Me (10)} and [{(η 5-C5Me5)MCl}2(bppp)]2 + {M = Rh (11); Ir (12)} have been synthesized from 3-chloro-6-(3-pyridyl-1-pyrazolyl)pyridazine (pp-Cl) or 3,6-bis(3-pyridyl-1-pyrazolyl)pyridazine (bppp) and the corresponding dimers [(η 6-arene)Ru(μ-Cl)Cl]2 and [Cp*M(μ-Cl)Cl]2, respectively. All complexes were isolated as their hexafluorophosphate salts and characterized by IR, NMR, mass spectrometry and UV-visible spectroscopy. The molecular structures of [2]PF6 and [7]PF6 have been established by single crystal X-ray structure analysis. The chelating ligands, 3-chloro-6-(3-pyridyl-1-pyrazolyl)pyridazine (pp-Cl) and 3,6-bis(3-pyridyl-1-pyrazolyl)pyridazine (bppp), were synthesized and their reactions with arene ruthenium, Cp* rhodium and Cp* iridium dimers resulted in the formation of mono and dinuclear complexes. The complexes were characterized by spectral techniques; the structures of representative compounds were confirmed by single crystal X-ray studies.