TY - JOUR

T1 - Tetrahedral nickel(ii) and cobalt(ii) bis-O-iminobenzosemiquinonates

AU - Ershova, Irina V.

AU - Smolyaninov, Ivan V.

AU - Bogomyakov, Artem S.

AU - Fedin, Matvey V.

AU - Starikov, Andrey G.

AU - Cherkasov, Anton V.

AU - Fukin, Georgy K.

AU - Piskunov, Alexandr V.

PY - 2019/6/19

Y1 - 2019/6/19

N2 - The new bis-o-iminobenzosemiquinonate nickel and cobalt complexes (imSQt-Bu)2M (M = Ni (1), Co (2)), where imSQ is a radical anion of 4,6-di-tert-butyl-N-(tert-butyl)-o-iminobenzoquinone, were synthesized and characterized in detail. The molecular structures of 1 and 2 have been established by single-crystal X-ray analysis. The metal atoms in 1 and 2 have a distorted tetrahedral environment, and the dihedral angles between the planes of two radical imSQ ligands are approximately 80° in both complexes. According to the structural and spectroscopy data along with magnetic susceptibility measurements the electronic structure of the complexes should be interpreted definitely as a high spin metal center NiII (d8, S = 1) in 1 and CoII (d7, S = 3/2) in 2 bonded with two o-iminobenzosemiquinonate radicals (Srad = 1/2). The strong antiferromagnetic metal-ligand spin interactions in both complexes lead to the observed St = 0 and St = 1/2 ground states in 1 and 2, respectively. The computational DFT UB3LYP/6-311++G(d,p) studies performed on 1 and 2 are in good agreement with experimental data. Complexes 1 and 2 have similar electrochemical properties. The electrochemical reduction of the complexes includes two quasi-reversible one-electron-transfer waves in the cathodic region corresponding to the formation of the anions [M(AP)2]2- and [(imSQ)M(AP)]1- (AP-dianion of 4,6-di-tert-butyl-N-(tert-butyl)-o-iminobenzoquinone), while in the anodic region only one quasi-reversible redox process was registered. All redox processes are shown to be ligand-based.

AB - The new bis-o-iminobenzosemiquinonate nickel and cobalt complexes (imSQt-Bu)2M (M = Ni (1), Co (2)), where imSQ is a radical anion of 4,6-di-tert-butyl-N-(tert-butyl)-o-iminobenzoquinone, were synthesized and characterized in detail. The molecular structures of 1 and 2 have been established by single-crystal X-ray analysis. The metal atoms in 1 and 2 have a distorted tetrahedral environment, and the dihedral angles between the planes of two radical imSQ ligands are approximately 80° in both complexes. According to the structural and spectroscopy data along with magnetic susceptibility measurements the electronic structure of the complexes should be interpreted definitely as a high spin metal center NiII (d8, S = 1) in 1 and CoII (d7, S = 3/2) in 2 bonded with two o-iminobenzosemiquinonate radicals (Srad = 1/2). The strong antiferromagnetic metal-ligand spin interactions in both complexes lead to the observed St = 0 and St = 1/2 ground states in 1 and 2, respectively. The computational DFT UB3LYP/6-311++G(d,p) studies performed on 1 and 2 are in good agreement with experimental data. Complexes 1 and 2 have similar electrochemical properties. The electrochemical reduction of the complexes includes two quasi-reversible one-electron-transfer waves in the cathodic region corresponding to the formation of the anions [M(AP)2]2- and [(imSQ)M(AP)]1- (AP-dianion of 4,6-di-tert-butyl-N-(tert-butyl)-o-iminobenzoquinone), while in the anodic region only one quasi-reversible redox process was registered. All redox processes are shown to be ligand-based.

KW - TRANSITION-METAL-COMPLEXES

KW - ELECTRON-TRANSFER SERIES

KW - NONINNOCENT LIGAND

KW - CRYSTAL-STRUCTURE

KW - OXIDATION-STATES

KW - SQUARE-PLANAR

KW - COORDINATION

KW - 4-COORDINATE

KW - NI

KW - NICKEL(O)-BIS(CHELATES)

UR - http://www.scopus.com/inward/record.url?scp=85069219075&partnerID=8YFLogxK

U2 - 10.1039/c9dt01424a

DO - 10.1039/c9dt01424a

M3 - Article

C2 - 31246209

AN - SCOPUS:85069219075

VL - 48

SP - 10723

EP - 10732

JO - Dalton Transactions

JF - Dalton Transactions

SN - 1477-9226

IS - 28

ER -