摘要
The preparation of complexes trans-[Ni(-SeC <sub>6</sub> H <sub>4</sub> -o-NH-) <sub>2</sub> ] <sup>-</sup> (1), cis-[Ni(-TeC <sub>6</sub> H <sub>4</sub> -o-NH-) <sub>2</sub> ] <sup>-</sup> (2), trans-[Ni(-SC <sub>6</sub> H <sub>4</sub> - o-NH-) <sub>2</sub> ] <sup>-</sup> (3), and [Ni(-SC <sub>6</sub> H <sub>4</sub> -o-S-) <sub>2</sub> ] <sup>-</sup> (4) by oxidative addition of 2-aminophenyl dichalcogenides to anionic [Ni(CO)(SePh) <sub>3</sub> ] <sup>-</sup> proves to be a successful approach in this direction. The cis arrangement of the two tellurium atoms in complex 2 is attributed to the intramolecular Te⋯Te contact interaction (Te⋯Te contact distance of 3.455 Å). The UV-vis electronic spectra of complexes 1 and 2 exhibit an intense absorption at 936 and 942 nm, respectively, with extinction coefficient ε > 10000 L mol <sup>-1</sup> cm <sup>-1</sup> . The observed small g anisotropy, the principal g values at g <sub>1</sub> = 2.036, g <sub>2</sub> = 2.062, and g <sub>3</sub> = 2.120 for 1 and g <sub>1</sub> = 2.021, g <sub>2</sub> = 2.119, and g <sub>3</sub> = 2.250 for 2, respectively, indicates the ligand radical character accompanied by the contribution of the singly occupied d orbital of Ni(III). The X-ray absorption spectra of all four complexes show L <sub>III</sub> peaks at ∼854.5 and ∼853.5 eV. This may indicate a variation of contribution of the Ni(II)-Ni(III) valence state. According to the DFT calculation, the unpaired electron of complex 1 and 2 is mainly distributed on the 3d <sub>xz</sub> orbital of the nickel ion and on the 4p <sub>z</sub> orbital of selenium (tellurium, 5p <sub>z</sub> ) as well as the 2p <sub>z</sub> orbital of nitrogen of the ligand. On the basis of X-ray structural data, UV-vis absorption, electron spin resonance, magnetic properties, DFT computation, and X-ray absorption (K- and L-edge) spectroscopy, the monoanionic trans-[Ni(-SeC <sub>6</sub> H <sub>4</sub> -o-NH-) <sub>2</sub> ] <sup>-</sup> and cis-[Ni(-TeC <sub>6</sub> H <sub>4</sub> -o-NH-) <sub>2</sub> ] <sup>-</sup> complexes are appositely described as a resonance hybrid form of Ni(III)-bis(o-amidochalcogenophenolato(2-)) and Ni(II)- (o-amidochalcogenophenolato(2-))-(o-iminochalcogenobenzosemiquinonato(1-) π-radical; i.e., complexes 1 and 2 contain delocalized oxidation levels of the nickel ion and ligands.