Imino-pyridyl and PPh3 mixed ligand complexes of Cu(I)X (X: I, Br, and Cl): Synthesis, structure, DFT and Hirshfeld surface studies

Abstract

Three new halide bridged copper(I)complexes [Cu₂(µ-L)(µ-X)₂)(PPh₃)₂]_n {X: I (1), Br (2) and Cl (3)} have been synthesized by the reaction of Cu(I)X (X: I, Br and Cl) with PPh₃ and the polydentate imino-pyridyl ligand L. Interestingly, copper(I) forms coordination polymers with the ligand L and the co-ligand PPh₃. These complexes 1, 2 and 3 have been characterized by elemental analysis, IR, UV-Vis, and NMR spectroscopy. The crystal structure of the complex 2 has been determined by single-crystal X-ray analysis. Crystal data for complex 2: triclinic, space group P-1 (no. 2), a = 9.471(10) Å, b = 11.043(11) Å, c = 13.215(18) Å, α = 65.853(18)°, β = 69.94(2)°, γ = 67.350(14)°, V = 1135(2) Å³, Z = 2, T = 296.15 K, μ(MoKα) = 2.806 mm^-1, D_calc = 1.535 g/cm³, 4059 reflections measured (3.462° ≤ 2Θ ≤ 44.818°), 2639 unique (R_int = 0.0637, R_sigma = 0.1621) which were used in all calculations. The final R₁ was 0.0700 (I > 2σ(I)) and wR₂ was 0.2207 (all data). Hirshfeld surface analysis of the complex 2 showed H···H, N···H and Br···H interactions of 55.9, 14.4 and 4.1%, respectively. MEP of ligand L reflects the whole molecule is reddish yellow in color because of equally distributed electron density over the molecule. For this reason, the ligand is supramolecularly arranged via -{Cu^I₂-µ-X₂} rhomboid core in the complex 2. The ligand L is non-emissive at room temperature in dichloromethane, whereas the complexes 1, 2 and 3 are photoluminescent. DFT and Hirshfeld surface studies have also been performed for complex 2.