Reactions of the cationic complex [(eta(5)-C5Me5)(2)Ir-2(mu(2)-H)(3)](+) with nitrogen-containing heterocycles in aqueous solution

The dinuclear cation [(eta (5)-C5Me5)(2)Ir2(mu (2)-H)(3)](+) (1) reacts in aqueous solution with pyrazole and 4-methylpyrazole to give the bispyrazola to complexes [(eta (5)-C5Me5)(2)Ir-2(mu (2)-H)(mu (2)-eta (1),eta (1)-N2C3H 2R)(2)](+) (R = H, 2; R = Me, 3). The reaction of complex 1 with 1,2,4-tria zole results in the formation of the bistriazolato complex [(mu (5)-C5Me5)( 2)Ir-2(mu (2)-H)(mu (2)-eta (1),eta (1)-N3C2H2)(2)](+) (4). Successive prot onation of the triazolato ligands in 4 leads to the complexes [(eta (5)-C5M e5)(2)Ir-2(mu (2)-H)(mu (2)-eta (1),eta (1)-N3C2H2)(mu (2)-eta (1),eta (1)- N3C2H3)](2+) (5) and [(eta (5)-C5Me5)(2)Ir-2(mu (2)-H)(mu (2)-eta (1),eta ( 1)-H3C2H3)(2)](3+) (6). The reaction of 1 with 1,2,3-triazole gives a 1:1 m ixture of the bistriazolato complexes [(eta (5)-C5Me5)(2)Ir-2(mu (2)-H)(mu (2)-eta (1),eta (1)-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, th e N-N axis being coordinated in a mu (2)-eta (1),eta (1) fashion. (C) 2001 Elsevier Science B.V. All rights reserved.