A novel coordination mode of κ(1)-N-Br-pyridylbenz-(imida, oxa or othia)-zole to Pt(ii): synthesis, characterization, electrochemical and structural analysis

Herein, three novel Pt(ii) complexes with formula [trans-Pt(Br-PyBenz-X)(Cl)(2)(DMSO)] (1–3) having Br-pyridylbenz-(imida, oxa or othia)-zole (L(1–3)) derivatives as potential bidentate ligands, under an unusual κ(1)-N-coordination mode are reported. All compounds were obtained straightforwardly via reaction of corresponding L(PB1–3) and [Pt(Cl)(2)(DMSO)(2)] (DMSO = dimethyl sulfoxide), at 100 °C in acetonitrile, respectively. 1–3 complexes were characterized by analytical and spectroscopic data: melting point, FT-IR, Raman, UV/Vis and NMR experiments. Cyclic voltammetry studies show an irreversible two-electron process at −0.50 and −0.51 V, which was ascribed to the Pt(ii)/Pt(iv) couple, for complexes 2 and 3. The crystal structure of complex 2 was elucidated by single-crystal X-ray diffraction, where the platinum atom exhibits a square plane geometry, where L(PB2) adopts an unusual mono-coordinated mode via an N-κ(1)-benzoxazole ring. According to DFT calculations the first N-coordination exchanging one DMSO molecule is favourable, while the second N-coordination is highly impeded.