Reactions of the cationic complex [(η5-C5Me5)2Ir2(μ2-H)3]+ with nitrogen-containing heterocycles in aqueous solution

The dinuclear cation [(η5-C5Me5)2Ir2(μ2-H)3]+ (1) reacts in aqueous solution with pyrazole and 4-methylpyrazole to give the bispyrazolato complexes [(η5-C5Me5)2Ir2(μ2-H)(μ2-η1,η1-N2C3H2R)2]+ (R=H, 2; R=Me, 3). The reaction of complex 1 with 1,2,4-triazole results in the formation of the bistriazolato complex [(η5-C5Me5)2Ir2(μ2-H)(μ2-η1,η1-N3C2H2)2]+ (4). Successive protonation of the triazolato ligands in 4 leads to the complexes [(η5-C5Me5)2Ir2(μ2-H)(μ2-η1,η1-N3C2H2)(μ2-η1,η1-N3C2H3)]2+ (5) and [(η5-C5Me5)2Ir2(μ2-H)(μ2-η1,η1-N3C2H3)2]3+ (6). The reaction of 1 with 1,2,3-triazole gives a 1:1 mixture of the bistriazolato complexes [(η5-C5Me5)2Ir2(μ2-H)(μ2-η1,η1-N3C2H2)2]+ with parallel (7a) and antiparallel (7b) coordination of the triazolato ligands. The X-ray structure analysis of 3 reveals a diiridium backbone which is bridged by two pyrazolato ligands, the N–N axis being coordinated in a μ2-η1,η1 fashion.