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A high-spin nickel(II) borohydride complex in dehalogenation

Title
A high-spin nickel(II) borohydride complex in dehalogenation
Authors
Tak, H[Tak, Hyeonwoo]Lee, H[Lee, Hyunjoo]Kang, J[Kang, Joongoo]Cho, J[Cho, Jaeheung]
DGIST Authors
Tak, H[Tak, Hyeonwoo]; Lee, H[Lee, Hyunjoo]; Kang, J[Kang, Joongoo]; Cho, J[Cho, Jaeheung]
Issue Date
2016
Citation
Inorganic Chemistry Frontiers, 3(1), 157-163
Type
Article
Article Type
Article
ISSN
2052-1553
Abstract
A nickel(ii)-borohydride complex bearing a macrocyclic tridentate N-donor ligand, [Ni(Me3-TACN)(BH4)(CH3CN)]+ (Me3-TACN = 1,4,7-trimethyl-1,4,7-triazacyclononane), was prepared, isolated, and characterized by various physicochemical methods, including UV-vis, ESI-MS, IR and X-ray analyses. The structural and spectroscopic characterization clearly shows that the borohydride ligand is bound to the high-spin nickel(ii) center in an η2-manner. Density functional theory calculations provided geometric information of 2, showing that the η2-binding of borohydride to the nickel center is more favorable than the η3-binding mode in CH3CN. The complex is paramagnetic with an effective magnetic moment of 2.9μB consistent with a d8 high-spin system. The reactivity of the high-spin nickel(ii)-borohydride complex was examined in dehalogenation with numerous halocarbons. A kinetic isotope effect value of 1.7 was observed in the dehalogenation of CHCl3 by the nickel(ii)-borohydride complex. Kinetic studies and isotopic labeling experiments implicate that hydride ion or hydrogen atom transfer from the borohydride group is the rate determining step. The positive Hammett ρ value of 1.2, obtained in the reactions of [Ni(Me3-TACN)(BH4)(CH3CN)]+ and para-substituted benzoyl chloride, indicates that the dehalogenation by the nickel(ii)-borohydride species occurs via a nucleophilic reaction. © the Partner Organisations 2016.
URI
http://hdl.handle.net/20.500.11750/2569
DOI
10.1039/c5qi00206k
Publisher
Royal Society of Chemistry
Files:
There are no files associated with this item.
Collection:
Emerging Materials ScienceComputational Materials Theory Group1. Journal Articles


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