Iridium Complexes with BIAN-Type Ligands: Synthesis, Structure and Redox Chemistry

A series of iridium complexes with bis(diisopropylphenyl)iminoacenaphtene (dpp-bian) ligands, [Ir(cod)(dpp-bian)Cl] (1), [Ir(cod)(NO)(dpp-bian)](BF4)2 (2) and [Ir(cod)(dpp-bian)](BF4) (3), were prepared characterized by spectroscopic techniques, elemental analysis, X-ray diffraction analysis cyclic voltammetry (CV). The structures 1–3 feature a square planar backbone consisting two C = π-bonds 1,5-cyclooctadiene (cod) nitrogen atoms dpp-bian supplemented chloride ion (for 1) or NO group 2) to complete square-pyramidal geometry. In the nitrosyl complex 2, Ir-N-O has bent geometry (the angle is 125°). CV data for 1 3 show reversible waves between 0 -1.6 V (vs. Ag/AgCl). Reversible oxidation was also found at E1/2 0.60 1. Magnetochemical measurements 2 in range from 1.77 300 K revealed an increase magnetic moment increasing temperature up 1.2 μB (at K). Nitrosyl unstable solution loses its yield (3). paramagnetic complex, [Ir(cod)(dpp-bian)](BF4)2 (4), detected as result decomposition. EPR spectrum 4 CH2Cl2 described spin Hamiltonian Ĥ gβHŜ S 1/2 gxx gyy 2.393 gzz 1.88, which are characteristic low-spin 5d7-Ir(II) state. DFT calculations carried out order rationalize experimental results.