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Preparation, Structure, and Properties of a Mixed‐Valent Ni II Ni III Amine‐Selenolate Complex
Author(s) -
Kersting Berthold,
Siebert Dieter
Publication year - 1999
Publication title -
european journal of inorganic chemistry
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.667
H-Index - 136
eISSN - 1099-0682
pISSN - 1434-1948
DOI - 10.1002/(sici)1099-0682(199901)1999:1<189::aid-ejic189>3.0.co;2-1
Subject(s) - chemistry , dication , triethylamine , electron paramagnetic resonance , cyclic voltammetry , crystal structure , tetraphenylborate , valence (chemistry) , crystallography , amine gas treating , medicinal chemistry , inorganic chemistry , stereochemistry , molecule , organic chemistry , ion , electrochemistry , physics , electrode , nuclear magnetic resonance
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 [Ni II 2 ( 1b ) 3 ]Cl ( 4a ) is readily prepared from 1b , NiCl 2 · 6 H 2 O, and NaOMe in methanol or by reaction of coordinatively unsaturated [Ni II 2 ( 1b ) 2 ][BPh 4 ] 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, [Ni II Ni III ( 1b ) 3 ] 2+ . The dication was prepared by air‐oxidation of 4a in MeOH and isolated as the dark‐brown BPh 4 − salt, [Ni II Ni III ( 1b ) 3 ][BPh 4 ] 2 · CH 3 OH ( 4b ). Mixed‐valent complex 4b consists of a dinuclear, face‐sharing bioctahedral dication with a central N 3 Ni II (μ 2 ‐SeR) 3 Ni III N 3 core and well‐separated tetraphenylborate anions. Distortions from D 3h 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 E 1 1/2 = –0.15 and at E 2 1/2 = +0.29 V vs SCE , affording 4b and the thermally not stable trication [Ni III 2 ( 1b ) 3 ] 3+ , respectively. The EPR spectrum of a powdered sample of 4b reveals an S = 3 / 2 ground state of the mixed‐valent Ni II Ni III complex.