Reactions of the cationic complex [(η 5-C 5Me 5) 2Ir 2(μ 2-H) 3] + with nitrogen-containing heterocycles in aqueous solution

Abstract

The dinuclear cation [(η 5-C 5Me 5) 2Ir 2(μ 2-H) 3] + ( 1) reacts in aqueous solution with pyrazole and 4-methylpyrazole to give the bispyrazolato complexes [(η 5-C 5Me 5) 2Ir 2(μ 2-H)(μ 2-η 1,η 1-N 2C 3H 2R) 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 [(η 5-C 5Me 5) 2Ir 2(μ 2-H)(μ 2-η 1,η 1-N 3C 2H 2) 2] + ( 4). Successive protonation of the triazolato ligands in 4 leads to the complexes [(η 5-C 5Me 5) 2Ir 2(μ 2-H)(μ 2-η 1,η 1-N 3C 2H 2)(μ 2-η 1,η 1-N 3C 2H 3)] 2+ ( 5) and [(η 5-C 5Me 5) 2Ir 2(μ 2-H)(μ 2-η 1,η 1-N 3C 2H 3) 2] 3+ ( 6). The reaction of 1 with 1,2,3-triazole gives a 1:1 mixture of the bistriazolato complexes [(η 5-C 5Me 5) 2Ir 2(μ 2-H)(μ 2-η 1,η 1-N 3C 2H 2) 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 μ 2-η 1,η 1 fashion.