Molecular and Electronic Structures of Tetrahedral Complexes of Nickel and Cobalt Containing N,N'-Disubstituted, Bulky o-Diiminobenzosemiquinonate(1-) 
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- 作者：Krzysztof Ch
//pubs.acs.org/images/entities/lstrok.gif" border="0">opek ; Eberhard Bothe ; Frank Neese ; Thomas Weyhermü ; ller ; Karl Wieghardt
- 刊名：Inorganic Chemistry
- 出版年：2006
- 出版时间：August 7, 2006
- 年：2006
- 卷：45
- 期：16
- 页码：6298 - 6307
- 全文大小：337K
- 年卷期：v.45,no.16(August 7, 2006)
- ISSN：1520-510X
文摘
The reaction of 2 equiv of the bulky ligand N,N'-bis(3,5-di-tert-butylphenyl)-1,2-phenylenediamine, H2[3LPDI], excesstriethylamine, and 1 equiv of M(CH3CO2)2·4H2O (M = Ni, Co) in the presence of air in CH3CN/CH2Cl2 solutionyields violet-black crystals of [NiII(3LISQ)2] CH3CN (1) or violet crystals of [Co(3L)2] (3). By using Pd(CH3CO2)2 asstarting material, green-blue crystals of [PdII(3LISQ)2]·CH3CN (2) were obtained. Single-crystal X-ray crystallographyrevealed that 1 and 3 contain (pseudo)tetrahedral neutral molecules [M(3L)2] (M = Ni, Co) whereas in 2 nearlysquare planar, neutral molecules [PdII(3LISQ)2] are present. Temperature-dependent susceptibility measurementsestablished that 1 and 2 are diamagnetic (S = 0) whereas 3 is paramagnetic with an S = 3/2 ground state. It isshown that 1 contains two 
radical benzosemiquinonate(1-)-type monoanions, ((3LISQ)1-
, Srad = 1/2), and acentral Ni(II) ion (d8; S = 1) which are antiferromagnetically coupled yielding the observed St = 0 ground state.This result has been confirmed by broken symmetry DFT calculations of 1. In contrast, the St = 3/2 ground stateof 3 is more difficult to understand: the two resonance structures [CoIII(3LISQ)(3LPDI)] 
[CoII(3LPDI)(3LIBQ)] might beinvoked (for tetrahedral [CoII(3LISQ)2] containing an SCo = 3/2 with two antiferromagnetically coupled -radical ligandsan St = 1/2 is anticipated). Complex 2 is diamagnetic (S = 0) containing a PdII ion (d8, SPd = 0 in an almostsquare planar ligand field) and two antiferromagnetically coupled ligand radicals (Srad = 1/2). The electrochemistryand spectroelectrochemistry of 1, 2, and 3 have been studied, and electron-transfer series comprising the species[M(L)2]z (z = 2+, 1+, 0, 1-, 2-) have been established. All oxidations and reductions are ligand centered.
radical benzosemiquinonate(1-)-type monoanions, ((3LISQ)1-, Srad = 1/2), and acentral Ni(II) ion (d8; S = 1) which are antiferromagnetically coupled yielding the observed St = 0 ground state.This result has been confirmed by broken symmetry DFT calculations of 1. In contrast, the St = 3/2 ground stateof 3 is more difficult to understand: the two resonance structures [CoIII(3LISQ)(3LPDI)] [CoII(3LPDI)(3LIBQ)] might beinvoked (for tetrahedral [CoII(3LISQ)2] containing an SCo = 3/2 with two antiferromagnetically coupled -radical ligandsan St = 1/2 is anticipated). Complex 2 is diamagnetic (S = 0) containing a PdII ion (d8, SPd = 0 in an almostsquare planar ligand field) and two antiferromagnetically coupled ligand radicals (Srad = 1/2). The electrochemistryand spectroelectrochemistry of 1, 2, and 3 have been studied, and electron-transfer series comprising the species[M(L)2]z (z = 2+, 1+, 0, 1-, 2-) have been established. All oxidations and reductions are ligand centered.