The synthesis, structural characterization, and reactivity of the first two-coordinate cobalt complex featuring a metal-element multiple bond [(IPr)Co(NDmp)] (4; IPr=1,3-bis(2',6'-diisopropylphenyl)imidazole-2-ylidene; Dmp=2,6-dimesitylphenyl) is reported. Complex 4 was prepared from the reaction of [(IPr)Co(η(2) -vtms)2 ] (vtms=vinyltrimethylsilane) with DmpN3 . An X-ray diffraction study revealed its linear C-Co-N core and a short Co-N distance (1.691(6) Å). Spectroscopic characterization and calculation studies indicated the high-spin nature of 4 and the multiple-bond character of the Co-N bond. Complex 4 effected group-transfer reactions to CO and ethylene to form isocyanide and imine, respectively. It also facilitated E-H (E=C, Si) σ-bond activation of terminal alkyne and hydrosilanes to produce the corresponding cobalt(II) alkynyl and cobalt(II) hydride complexes as 1,2-addition products.
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http://dx.doi.org/10.1002/anie.201505937 | DOI Listing |
Inorg Chem
January 2022
Jiangsu Key Lab for NSLSCS, School of Physical Science and Technology, Nanjing Normal University, Nanjing 210023, P. R. China.
Complete-active-space self-consistent field and N-electron valence second-order perturbation theory have both been employed to investigate the magnetic anisotropy of one two-coordinate cobalt(II) compound altering the Co-C bond lengths and twist angle φ. The calculated energy barrier decreases with the decrease in the Co-C bond lengths due to the gradually increasing interaction between the 3d orbitals of Co and the coordination ligand field and then to the decrease in the ground orbital angular moment of Co. Thus, we cannot improve simply by shortening the Co-C bond lengths.
View Article and Find Full Text PDFChem Sci
January 2019
Department of Chemistry , Yale University, New Haven , Connecticut 06520 , USA . Email:
Fixation and chemical reduction of CO are important for utilization of this abundant resource, and understanding the detailed mechanism of C-O cleavage is needed for rational development of CO reduction methods. Here, we describe a detailed analysis of the mechanism of the reaction of a masked two-coordinate cobalt(i) complex, L Co (where L = 2,2,6,6-tetramethyl-3,5-bis[(2,6-diisopropylphenyl)imino]hept-4-yl), with CO, which yields two products of C-O cleavage, the cobalt(i) monocarbonyl complex L Co(CO) and the dicobalt(ii) carbonate complex (L Co)(μ-CO). Kinetic studies and computations show that the κ,η-arene isomer of L Co rearranges to the κ , binding mode prior to binding of CO, which contrasts with the mechanism of binding of other substrates to L Co.
View Article and Find Full Text PDFAngew Chem Int Ed Engl
October 2015
State Key Laboratory of Organometallic Chemistry, Shanghai Institute of Organic Chemistry, Chinese Academy of Sciences, 345 Lingling Road, Shanghai, 200032 (P.R. China) http://dengliang.sioc.ac.cn/.
The synthesis, structural characterization, and reactivity of the first two-coordinate cobalt complex featuring a metal-element multiple bond [(IPr)Co(NDmp)] (4; IPr=1,3-bis(2',6'-diisopropylphenyl)imidazole-2-ylidene; Dmp=2,6-dimesitylphenyl) is reported. Complex 4 was prepared from the reaction of [(IPr)Co(η(2) -vtms)2 ] (vtms=vinyltrimethylsilane) with DmpN3 . An X-ray diffraction study revealed its linear C-Co-N core and a short Co-N distance (1.
View Article and Find Full Text PDFInorg Chem
March 2014
Department of Chemistry, University of California, Davis, One Shields Avenue, Davis, California 95616, United States.
Treatment of the cobalt(II) amide, [Co{N(SiMe3)2}2]2, with four equivalents of the sterically crowded terphenyl phenols, HOAr(Me6) (Ar(Me6) = C6H3-2,6(C6H2-2,4,6-Me3)2) or HOAr(iPr4) (Ar(iPr4) = C6H3-2,6(C6H3-2,6-Pr(i)2)2), produced the first well-characterized, monomeric two-coordinate cobalt(II) bisaryloxides, Co(OAr(Me6))2 (1) and Co(OAr(iPr4))2 (2a and 2b), as red solids in good yields with elimination of HN(SiMe3)2. The compounds were characterized by electronic spectroscopy, X-ray crystallography, and direct current magnetization measurements. The O-Co-O interligand angles in 2a and 2b are 180°, whereas the O-Co-O angle in 1 is bent at 130.
View Article and Find Full Text PDFChem Commun (Camb)
July 2010
Department of Chemistry, University of California, One Shields Avenue, Davis, CA 95616, USA.
The synthesis and characterization of two-coordinate cobalt(ii) complexes CoAr'(2) (1) and Ar'CoN(SiMe(3))(2) (2) (Ar' = C(6)H(3)-2,6-(C(6)H(3)-2,6-(i)Pr(2))(2)) are reported. The magnetic data for 2 show that it has an unexpectedly high mu(eff) of 5.65 mu(B) whereas the bent complex 1 has a significantly lower moment.
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