Electronic Structure of Bis (tropolonato) nickel (II)

Mikiko WADA, Miki HASEGAWA, Michio KOBAYASHI, Tetsutaro YOSHINAGA†, Hiroshi HIRATSUKA†† and Toshihiko HOSHI*

Department of Chemistry, College of Science and Engineering, Aoyama Gakuin University; Chitosedai, Setagaya-ku, Tokyo 157-8572 Japan
† Department of Chemistry, Faculty of Engineering, Kyushu Institute of Technology; Sensuicho, Tobata-ku, Kitakyushu-shi 804-8550 Japan
†† Department of Chemistry, Faculty of Engineering, Gunma University; Tenjincho, Kiryu-shi 376-8515 Japan

1H-NMR, X-ray photoelectron, and electronic absorption spectra have been measured for two kinds of complexes, monomer troNi (II) and dimer (troNi (II) ) 2, which are formed between tropolone and nickel (II) . From these spectral data together with MO calculations using a modified Pariser-Parr-Pople approximation, the electronic and molecular structure of the above complexes has been clarified. In the solid state, the central metal ion of troNi (II) takes a tetrahedral sp3 hybridization. On the other hand, in solution, the metal ion takes an octahedral d2sp3 hybridization, being linked with solvent or water (contained in the solvent) molecules. Furthermore in solution, the two tropolonato skeletal planes are coplanar, and are arranged transoid. The 402, 339 and 240.2 nm bands of troNi (II) observed in ethanol are assigned to the calculated ππ*2, ππ*3 and ππ*11 transitions, respectively. A weak band observed at around 674 nm is due to d-d transitions. The XPS Ni2p band of troNi (II) is observed at 857.8 eV, and that of (troNi (II) ) 2 at 858 eV. Both bands accompany with shake-up bands, indicating that the two complexes are paramagnetic in the solid states.


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