Cited 0 time in webofscience Cited 0 time in scopus

Synthesis, Characterization and Reactivity of a Mononuclear Nickel(II)-Borohydride Complex

Title
Synthesis, Characterization and Reactivity of a Mononuclear Nickel(II)-Borohydride Complex
Authors
Tak, Hyeon Woo
DGIST Authors
Tak, Hyeon Woo; Cho, Jae Heung; Kim, Hyun Chul
Advisor(s)
Cho, Jae Heung
Co-Advisor(s)
Kim, Hyun Chul
Issue Date
2016
Available Date
2016-08-18
Degree Date
2016. 8
Type
Thesis
Keywords
High-spin nickell(II)-borohydride complexdehalogenation고스핀 니켈-보로하이드라이드 화합물탈할로겐반응
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 2.9 μB 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. ⓒ 2016 DGIST
Table Of Contents
Ⅰ. Introduction 1 -- 1.1 Motivation 1 -- 1.2 Previous work 1 -- 1.3 This work 2 -- Ⅱ. Results and discussion 3 -- 2.1 Nickel(II) precursor complex 3 -- 2.2 Nickel(II)–borohydride complex and characterization 5 -- 2.3 Reactivity 2 -- 2.4 Density functional theory results 19 -- Ⅲ. Conclusions 27 -- 3.1 Conclusions 27 -- Ⅳ. Experimental section 28 -- 4.1 Materials 28 -- 4.2 Physical methods 28 -- 4.3 Syntheses 29 -- 4.3.1 [Ni(Me3-TACN)(CH3CN)2](ClO4)2 (1-(ClO4)2) 29 -- 4.3.2 [Ni(Me3-TACN)(BH4)(CH3CN)](BPh4) (2-(BPh4)) 29 -- 4.4 X-ray crystallography 30 -- 4.5 Reactivity 31 -- 4.6 Computational details 31
URI
http://dgist.dcollection.net/jsp/common/DcLoOrgPer.jsp?sItemId=000002296548
http://hdl.handle.net/20.500.11750/1472
DOI
10.22677/thesis.2296548
Degree
Master
Department
Emerging materials Science
University
DGIST
Files:
Collection:
Emerging Materials ScienceThesesMaster


qrcode mendeley

Items in DSpace are protected by copyright, with all rights reserved, unless otherwise indicated.

BROWSE