Spectroscopic Analyses on Reaction Intermediates Formed during Chlorination of Alkanes with NaOCl Catalyzed by a Nickel Complex
dc.contributor.author
dc.date.accessioned
2016-02-23T11:25:17Z
dc.date.available
2016-02-23T11:25:17Z
dc.date.issued
2015-11-05
dc.identifier.issn
0020-1669
dc.identifier.uri
dc.description.abstract
The spectroscopic, electrochemical, and crystallographic characterization of [(Me,HPyTACN)NiII(CH3CN)2](OTf)2 (1) (Me,HPyTACN = 1-(2-pyridylmethyl)-4,7-dimethyl-1,4,7-triazacyclononane, OTf = CF3SO3) is described together with its reactivity with NaOCl. 1 catalyzes the chlorination of alkanes with NaOCl, producing only a trace amount of oxygenated byproducts. The reaction was monitored spectroscopically and by high resolution electrospray-mass spectrometry (ESI-MS) with the aim to elucidate mechanistic aspects. NaOCl reacts with 1 in acetonitrile to form the transient species [(L)NiII-OCl(S)]+ (A) (L = Me,HPyTACN, S = solvent), which was identified by ESI-MS. UV/vis absorption, electron paramagnetic resonance, and resonance Raman spectroscopy indicate that intermediate A decays to the complex [(L)NiIII-OH(S)]2+ (B) presumably through homolytic cleavage of the O-Cl bond, which liberates a Cl• atom. Hydrolysis of acetonitrile to acetic acid under the applied conditions results in the formation of [(L)NiIII-OOCCH3(S)]2+ (C), which undergoes subsequent reduction to [(L)NiII-OOCCH3(S)]2+ (D), presumably via reaction with OCl- or ClO2 -. Subsequent addition of NaOCl to [(L)NiII-OOCCH3(S)]+ (D) regenerates [(L)NiIII-OH(S)]2+ (B) to a much greater extent and at a faster rate. Addition of acids such as acetic and triflic acid enhances the rate and extent of formation of [(L)NiIII-OH(S)]2+ (B) from 1, suggesting that O-Cl homolytic cleavage is accelerated by protonation. Overall, these reactions generate Cl• atoms and ClO2 in a catalytic cycle where the nickel center alternates between Ni(II) and Ni(III). Chlorine atoms in turn react with the C-H bonds of alkanes, forming alkyl radicals that are trapped by Cl• to form alkyl chlorides
dc.description.sponsorship
Financial support comes from the European Research Council (ERC-2011-StG-279549, W.R.B. and ERC-2009-StG-239910, M.C.), The Netherlands Fund for Technology and Science STW (11059, W.R.B.) the Ministry of Education, Culture and Science (Gravity program 024.001.035, A.D., W.R.B.) and the Ubbo Emmius Fund of the University of Groningen (AD). M.C. thanks MINECO of Spain (CTQ2012 37420-C02-01/BQU, CSD2010-00065) and Generalitat de Catalunya (2009SGR637, and ICREA Acadèmia Award)
dc.format.mimetype
application/pdf
dc.language.iso
eng
dc.publisher
American Chemical Society (ACS)
dc.relation
info:eu-repo/grantAgreement/MINECO//CTQ2012-37420-C02-01/ES/DISEÑO BIOINSPIRADO DE CATALIZADORES PARA LA OXIDACION DE ENLACES C-H, C=C Y AGUA/
MICINN/PN 2010-2016/CSD2010-00065
AGAUR/2009-2014/2009 SGR-637
dc.relation.isformatof
Reproducció digital del document publicat a: http://dx.doi.org/10.1021/acs.inorgchem.5b01463
dc.relation.ispartof
© Inorganic Chemistry, 2015, vol. 54, p. 10656-10666
dc.relation.ispartofseries
Articles publicats (D-Q)
dc.rights
Tots els drets reservats
dc.subject
dc.title
Spectroscopic Analyses on Reaction Intermediates Formed during Chlorination of Alkanes with NaOCl Catalyzed by a Nickel Complex
dc.type
info:eu-repo/semantics/article
dc.rights.accessRights
info:eu-repo/semantics/embargoedAccess
dc.embargo.terms
Cap
dc.date.embargoEndDate
info:eu-repo/date/embargoEnd/2026-01-01
dc.relation.projectID
info:eu-repo/grantAgreement/EC/FP7/239910/EU/Bio-inspired Design of Catalysts for Selective Oxidations of C-H and C=C Bonds/BIDECASEOX
dc.type.version
info:eu-repo/semantics/publishedVersion
dc.identifier.doi
dc.identifier.idgrec
024610
dc.contributor.funder
dc.relation.FundingProgramme
dc.relation.ProjectAcronym
dc.identifier.eissn
1520-510X