Novel mononuclear η5-pentamethylcyclopentadienyl complexes of platinum group metals bearing pyrazolylpyridazine ligands: Syntheses and spectral studies

Condensation of 3,6-dichloropyridazine with 3,5-dimethylpyrazole in 1:1 ratio yielded one side substituted pyrazolylpyridazine ligand 3-chloro-6-(3,5-dimethylpyrazolyl)pyridazine (L) while condensation of 3,6-dichloropyridazine with substituted pyrazoles in 1:2 ratio yielded both side substituted pyrazolylpyridazine ligands such as 3,6-bis(pyrazolyl)pyridazine (L1), 3,6-bis(3-methylpyrazolyl)pyridazine (L2) and 3,6-bis(3,5-dimethylpyrazolyl)pyridazine (L3). A new series of cationic mononuclear complexes of the type [(η5-Cp)Ma(L)(PPh3)]PF6, [(η5-Cp*)Mb(L)Cl]PF6, [(η5-Cp*)Ru(L′)(PPh3)]PF6 and [(η5-Cp*)Mb(L′)Cl]+ (where Ma = Ru, Os; Mb = Rh, Ir and L′ = L1, L2, L3) bearing pyrazolylpyridazine and η5-cyclopentadienyl ligands are reported. The complexes have been completely characterized by spectral studies. The molecular structures of representative complexes have been determined by single crystal X-ray crystallography.