TY - JOUR
T1 - Stabilization of a cobalt-cobalt bond by two cyclic alkyl amino carbenes
AU - Mondal, Kartik Chandra
AU - Samuel, Prinson P.
AU - Roesky, Herbert W.
AU - Carl, Elena
AU - Herbst-Irmer, Regine
AU - Stalke, Dietmar
AU - Schwederski, Brigitte
AU - Kaim, Wolfgang
AU - Ungur, Liviu
AU - Chibotaru, Liviu F.
AU - Hermann, Markus
AU - Frenking, Gernot
PY - 2014/2/5
Y1 - 2014/2/5
N2 - (Me2-cAAC:)2Co2 (2, where Me 2-cAAC: = cyclic alkyl amino carbene,:C(CH2)(CMe 2)2N-2,6-iPr2C6H3)) was synthesized via the reduction of precursor (Me2-cAAC:Co II(μ-Cl)Cl)2 (1) with KC8. 2 contains two cobalt atoms in the formal oxidation state zero. Magnetic measurement revealed that 2 has a singlet spin ground state S = 0. The cyclic voltammogram of 2 exhibits both one-electron oxidation and reduction, indicating the possible synthesis of stable species containing 2•- and 2 •+ ions. The latter was synthesized via reduction of 1 with required equivalents of KC8 and characterized as [(Me 2-cAAC:)2Co2]•+OTf- (2•+OTf-). Electron paramagnetic resonance spectroscopy of 2•+ reveals the coupling of the electron spin with 2 equiv 59Co isotopes, leading to a (Co0.5) 2 state. The experimental Co1-Co2 bond distances are 2.6550(6) and 2.4610(6) Å for 2 and 2•+OTf-, respectively. Theoretical investigation revealed that both 2 and 2•+OTf - possess a Co-Co bond with an average value of 2.585 Å. A slight increase of the Co-Co bond length in 2 is more likely to be caused by the strong π-accepting property of cAAC. 2•+ is only 0.8 kcal/mol higher in energy than the energy minimum. The shortening of the Co-Co bond of 2•+ is caused by intermolecular interactions.
AB - (Me2-cAAC:)2Co2 (2, where Me 2-cAAC: = cyclic alkyl amino carbene,:C(CH2)(CMe 2)2N-2,6-iPr2C6H3)) was synthesized via the reduction of precursor (Me2-cAAC:Co II(μ-Cl)Cl)2 (1) with KC8. 2 contains two cobalt atoms in the formal oxidation state zero. Magnetic measurement revealed that 2 has a singlet spin ground state S = 0. The cyclic voltammogram of 2 exhibits both one-electron oxidation and reduction, indicating the possible synthesis of stable species containing 2•- and 2 •+ ions. The latter was synthesized via reduction of 1 with required equivalents of KC8 and characterized as [(Me 2-cAAC:)2Co2]•+OTf- (2•+OTf-). Electron paramagnetic resonance spectroscopy of 2•+ reveals the coupling of the electron spin with 2 equiv 59Co isotopes, leading to a (Co0.5) 2 state. The experimental Co1-Co2 bond distances are 2.6550(6) and 2.4610(6) Å for 2 and 2•+OTf-, respectively. Theoretical investigation revealed that both 2 and 2•+OTf - possess a Co-Co bond with an average value of 2.585 Å. A slight increase of the Co-Co bond length in 2 is more likely to be caused by the strong π-accepting property of cAAC. 2•+ is only 0.8 kcal/mol higher in energy than the energy minimum. The shortening of the Co-Co bond of 2•+ is caused by intermolecular interactions.
UR - http://www.scopus.com/inward/record.url?scp=84893767062&partnerID=8YFLogxK
U2 - 10.1021/ja4123285
DO - 10.1021/ja4123285
M3 - 文章
AN - SCOPUS:84893767062
SN - 0002-7863
VL - 136
SP - 1770
EP - 1773
JO - Journal of the American Chemical Society
JF - Journal of the American Chemical Society
IS - 5
ER -