Preparation of metalated azine complexes of iridium(iii)

Abstract

Arylaldazine and acetoneazine complexes [IrCl(η⁵-C₅Me₅){κ¹-[NC(H)(R2C₆H₄)]–NC(H)(R2C₆H₄)}{P(OR1)₃}]BPh₄ (1, 2) and [IrCl(η⁵-C₅Me₅){κ¹-[NC(CH₃)₂]–NC(CH₃)₂}{P(OR1)₃}]BPh₄ (3, 4) [R1 = Me (1, 3), Et (2, 4); R2 = H (a), 4-CH₃ (b), 2,6-(CH₃)₂ (f)] were prepared by allowing chloro complexes IrCl₂(η⁵-C₅Me₅)[P(OR1)₃] to react first with AgOTf and then with the appropriate azine. In solution, κ¹-complexes 1–4 undergo a metalation reaction, affording chelate κ²-azine derivatives [Ir{κ²-R2C₆H₃(H)CN–NC(H)(R2C₆H₄)}(η⁵-C₅Me₅){P(OR1)₃}]BPh₄ (5, 6) and [Ir{κ²-CH₂(CH₃)CN–NC(CH₃)₂}(η⁵-C₅Me₅){P(OR1)₃}]BPh₄ (7, 8) [R1 = Me (5, 7), Et (6, 8); R2 = H (a), 4-CH₃ (b), 4-CH₃O (c); 4-F (d), 4-NO₂ (e)]. The complexes were characterised spectroscopically and by X-ray crystal structure determination of [Ir{κ²-C₆H₄(H)CN–NC(H)(C₆H₅)}(η⁵-C₅Me₅){P(OEt)₃}]BPh₄ (6a). Most of the κ²-arylazine derivatives showed photoluminescence properties upon excitation with near-UV and violet light, with emission peaks at around 650 nm. The photoluminescence features were rationalised according to DFT calculations.