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

• Published in: International journal of molecular sciences 2023-06, Vol.24 (13), p.10457
• Main Authors: Romashev, Nikolai F, Bakaev, Ivan V, Komlyagina, Veronika I, Abramov, Pavel A, Mirzaeva, Irina V, Nadolinny, Vladimir A, Lavrov, Alexander N, Kompan'kov, Nikolai B, Mikhailov, Artem A, Fomenko, Iakov S, Novikov, Alexander S, Sokolov, Maxim N, Gushchin, Artem L
• Format: Article
• Language: English
• Subjects: Chemical Sciences; Crystallography, X-Ray; Dichloromethane; Hydrogenation; Iridium - chemistry; Iridium compounds; Ligands; Magnetic moments; Nitrogen; Nitrogen atoms; Oxidation; Oxidation-Reduction; Silver chloride; Single crystals; Spectrum Analysis; X-ray diffraction
• ISSN: 1422-0067; 1661-6596; 1422-0067
• DOI: 10.3390/ijms241310457

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