Reactivity studies of (η6-arene)ruthenium dimeric complexes towards pyrazoles: isolation of amidines, bis pyrazoles and chloro bridged pyrazole complexes

The complex [(η6-p-cymene)Ru(μ-Cl)Cl]2 1 reacts with pyrazole ligands (3a–g) in acetonitrile to afford the amidine derivatives of the type [(η6-p-cymene)Ru(L)(3,5-HRR′pz)](BF4)2 (4a–f), where L={HNC(Me)3,5-RR′pz}; R, R′=H (4a); H, CH3 (4b); C6H5 (4c); CH3, C6H5 (4d) OCH3 (4e); and OC2H5 (4f), respectively. The ligand L is generated in situ through the condensation of 3,5-HRR′pz with acetonitrile under the influence of [(η6-p-cymene)RuCl2]2. The …