Preparation, Structure, and Properties of a Mixed-Valent NiIINiIII Amine-Selenolate Complex

Autor: Dieter Siebert, Berthold Kersting
Rok vydání: 1999
Předmět:
Zdroj: European Journal of Inorganic Chemistry. 1999:189-193
ISSN: 1099-0682
1434-1948
DOI: 10.1002/(sici)1099-0682(199901)1999:1<189::aid-ejic189>3.0.co;2-1
Popis: Two dinuclear nickel amine-selenolate complexes of the tridentate amine-selenolate ligand, 4-tert-butyl-2,6-di(aminomethyl)selenophenol (1b), have been synthesized and their properties characterized. The green complex [NiII2(1b)3]Cl (4a) is readily prepared from 1b, NiCl2 · 6 H2O, and NaOMe in methanol or by reaction of coordinatively unsaturated [NiII2(1b)2][BPh4]2 (2b) with another one equivalent of 1b in the presence of triethylamine. The face-sharing, bioctahedral structure of 4a is derived from UV/Vis spectroscopy, cyclic voltammetry, and single-crystal X-ray diffraction of its oxidation product, [NiIINiIII(1b)3]2+. The dication was prepared by air-oxidation of 4a in MeOH and isolated as the dark-brown BPh4− salt, [NiIINiIII(1b)3][BPh4]2 · CH3OH (4b). Mixed-valent complex 4b consists of a dinuclear, face-sharing bioctahedral dication with a central N3NiII(μ2-SeR)3NiIIIN3 core and well-separated tetraphenylborate anions. Distortions from D3h symmetry suggest that 4b is a trapped-valence compound in the solid-state. On the CV time scale complex 4a undergoes two reversible one-electron oxidations at E11/2 = –0.15 and at E21/2 = +0.29 V vs SCE, affording 4b and the thermally not stable trication [NiIII2(1b)3]3+, respectively. The EPR spectrum of a powdered sample of 4b reveals an S = 3/2 ground state of the mixed-valent NiIINiIII complex.
Databáze: OpenAIRE
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