Structural comparison of (pentamethylcyclopentadienyl)iridium(III) azido complexes containing potentially N,S-bidentate N-heterocyclic thiolates: 2- or 8-quinolinethiolate and benzimidazole-2-thiolate

The crystal structures of mononuclear (azido)(pentamethylcyclopentadienyl)iridium(III) complexes bearing 2- or 8-quinolinethiolate (n-Sqn−), [Cp∗Ir(N3)(n-Sqn)] {n = 2 (1) or 8 (2); Cp∗ = η5-C5Me5} have been determined by X-ray analysis. The 2-Sqn complex, 1, acquires severe steric strains in the four-membered κ2N,S chelate ring, while the 8-Sqn isomer, 2, forms a strain-free five-membered planar κ2N,S chelate ring. It has also been revealed that the corresponding benzimidazole-2-thiolate (Hbimt−) complex, which was obtained similarly to the above n-Sqn complexes from [Cp∗Ir(N3)2]2 and Na(Hbimt), takes an unsymmetrical dinuclear structure bridged by two Hbimt− ligands with different bonding modes, [Cp∗Ir(N3){μ(S:N1)-Hbimt}{μ(S:S)-Hbimt}Ir(N3)Cp∗] · MeOH (3).

Graphical abstractThe crystal structures of [Cp∗Ir(2-Sqn-κ2N,S)(N3)] (1), [Cp∗Ir(8-Sqn-κ2N,S)(N3)] (2) and [Cp∗Ir(N3){μ(S:N1)-Hbimt}{μ(S:S)-Hbimt}Ir(N3)Cp∗] · MeOH (3) have been determined by X-ray analysis. It has been revealed that the Hbimt complex has a novel unsymmetrical core structure with a six-membered diiridacycle consisting of (Ir,S,C,N,Ir,S) in a skew-boat conformation.Figure optionsDownload full-size imageDownload as PowerPoint slide