(N-Benzyl-bis-N′,N″-salicylidene)-cis-1,3,5-triaminocyclohex ane copper(ii): A novel catalyst for the aerobic oxidation of benzyl alcohol

Alison K. Nairn; Stephen J. Archibald; Rajiv Bhalla; Bruce C. Gilbert; Elizabeth J. MacLean; Simon J. Teat; Paul H. Walton

doi:10.1039/b512296c

(N-Benzyl-bis-N′,N″-salicylidene)-cis-1,3,5-triaminocyclohex ane copper(ii): A novel catalyst for the aerobic oxidation of benzyl alcohol

Alison K. Nairn, Stephen J. Archibald, Rajiv Bhalla, Bruce C. Gilbert, Elizabeth J. MacLean, Simon J. Teat, Paul H. Walton^*

^*Corresponding author for this work

Imaging Chemistry & Biology

Research output: Contribution to journal › Article › peer-review

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Abstract

Reaction of Cu(BF₄)₂·6H₂O with the N₃O₂ donor ligand H₂L (where H₂L = N-benzyl-N′,N″-di-tert-butyl-disalicyl-triaminocyclohexane) results in the formation of a novel Cu^IIL complex, 1. X-Ray crystallography of 1 shows the Cu^II centre coordinated by two phenolate oxygens and two imine nitrogens in a distorted square plane with an elongated bond to the amine nitrogen (2.512 Å) in the axial position. EPR spectroscopy of 1 gives g values of g₁ = 2.277, g₂ = 2.100, g₃ = 2.025, and A₁ = 15.6 mT which are consistent with the distorted square pyramidal coordination environment determined from the X-ray structure. UV/visible and electrochemical analysis of 1 shows that it undergoes two reversible processes assigned to the successive oxidation of the phenolate oxygens to phenoxyl radicals, the first at E_1/2 = 0.89 V (ΔE = 81 mV, vs. Ag/AgCl) and the second at E_1/2 = 1.13V (ΔE = 84 mV, vs. Ag/AgCl). Chemical oxidation of 1 results in the formation of a species, assigned as [1]⁺ which is EPR silent due to antiferromagnetic coupling between the Cu^II centre and the bound phenoxyl radical. The oxidised species catalyses the oxidation of benzyl alcohol to benzaldehyde.

Original language	English
Pages (from-to)	172-176
Number of pages	5
Journal	Dalton Transactions
Issue number	1
DOIs	https://doi.org/10.1039/b512296c
Publication status	Published - 2006

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title = "(N-Benzyl-bis-N′,N″-salicylidene)-cis-1,3,5-triaminocyclohex ane copper(ii): A novel catalyst for the aerobic oxidation of benzyl alcohol",

abstract = "Reaction of Cu(BF4)2·6H2O with the N3O2 donor ligand H2L (where H2L = N-benzyl-N′,N″-di-tert-butyl-disalicyl-triaminocyclohexane) results in the formation of a novel CuIIL complex, 1. X-Ray crystallography of 1 shows the CuII centre coordinated by two phenolate oxygens and two imine nitrogens in a distorted square plane with an elongated bond to the amine nitrogen (2.512 {\AA}) in the axial position. EPR spectroscopy of 1 gives g values of g1 = 2.277, g2 = 2.100, g3 = 2.025, and A1 = 15.6 mT which are consistent with the distorted square pyramidal coordination environment determined from the X-ray structure. UV/visible and electrochemical analysis of 1 shows that it undergoes two reversible processes assigned to the successive oxidation of the phenolate oxygens to phenoxyl radicals, the first at E1/2 = 0.89 V (ΔE = 81 mV, vs. Ag/AgCl) and the second at E1/2 = 1.13V (ΔE = 84 mV, vs. Ag/AgCl). Chemical oxidation of 1 results in the formation of a species, assigned as [1]+ which is EPR silent due to antiferromagnetic coupling between the CuII centre and the bound phenoxyl radical. The oxidised species catalyses the oxidation of benzyl alcohol to benzaldehyde.",

author = "Nairn, {Alison K.} and Archibald, {Stephen J.} and Rajiv Bhalla and Gilbert, {Bruce C.} and MacLean, {Elizabeth J.} and Teat, {Simon J.} and Walton, {Paul H.}",

year = "2006",

doi = "10.1039/b512296c",

language = "English",

pages = "172--176",

journal = "Dalton Transactions",

issn = "1477-9226",

publisher = "Royal Society of Chemistry",

number = "1",

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T1 - (N-Benzyl-bis-N′,N″-salicylidene)-cis-1,3,5-triaminocyclohex ane copper(ii)

T2 - A novel catalyst for the aerobic oxidation of benzyl alcohol

AU - Nairn, Alison K.

AU - Archibald, Stephen J.

AU - Bhalla, Rajiv

AU - Gilbert, Bruce C.

AU - MacLean, Elizabeth J.

AU - Teat, Simon J.

AU - Walton, Paul H.

PY - 2006

Y1 - 2006

N2 - Reaction of Cu(BF4)2·6H2O with the N3O2 donor ligand H2L (where H2L = N-benzyl-N′,N″-di-tert-butyl-disalicyl-triaminocyclohexane) results in the formation of a novel CuIIL complex, 1. X-Ray crystallography of 1 shows the CuII centre coordinated by two phenolate oxygens and two imine nitrogens in a distorted square plane with an elongated bond to the amine nitrogen (2.512 Å) in the axial position. EPR spectroscopy of 1 gives g values of g1 = 2.277, g2 = 2.100, g3 = 2.025, and A1 = 15.6 mT which are consistent with the distorted square pyramidal coordination environment determined from the X-ray structure. UV/visible and electrochemical analysis of 1 shows that it undergoes two reversible processes assigned to the successive oxidation of the phenolate oxygens to phenoxyl radicals, the first at E1/2 = 0.89 V (ΔE = 81 mV, vs. Ag/AgCl) and the second at E1/2 = 1.13V (ΔE = 84 mV, vs. Ag/AgCl). Chemical oxidation of 1 results in the formation of a species, assigned as [1]+ which is EPR silent due to antiferromagnetic coupling between the CuII centre and the bound phenoxyl radical. The oxidised species catalyses the oxidation of benzyl alcohol to benzaldehyde.

AB - Reaction of Cu(BF4)2·6H2O with the N3O2 donor ligand H2L (where H2L = N-benzyl-N′,N″-di-tert-butyl-disalicyl-triaminocyclohexane) results in the formation of a novel CuIIL complex, 1. X-Ray crystallography of 1 shows the CuII centre coordinated by two phenolate oxygens and two imine nitrogens in a distorted square plane with an elongated bond to the amine nitrogen (2.512 Å) in the axial position. EPR spectroscopy of 1 gives g values of g1 = 2.277, g2 = 2.100, g3 = 2.025, and A1 = 15.6 mT which are consistent with the distorted square pyramidal coordination environment determined from the X-ray structure. UV/visible and electrochemical analysis of 1 shows that it undergoes two reversible processes assigned to the successive oxidation of the phenolate oxygens to phenoxyl radicals, the first at E1/2 = 0.89 V (ΔE = 81 mV, vs. Ag/AgCl) and the second at E1/2 = 1.13V (ΔE = 84 mV, vs. Ag/AgCl). Chemical oxidation of 1 results in the formation of a species, assigned as [1]+ which is EPR silent due to antiferromagnetic coupling between the CuII centre and the bound phenoxyl radical. The oxidised species catalyses the oxidation of benzyl alcohol to benzaldehyde.

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U2 - 10.1039/b512296c

DO - 10.1039/b512296c

M3 - Article

AN - SCOPUS:33645548530

SN - 1477-9226

SP - 172

EP - 176

JO - Dalton Transactions

JF - Dalton Transactions

IS - 1

ER -

(N-Benzyl-bis-N′,N″-salicylidene)-cis-1,3,5-triaminocyclohex ane copper(ii): A novel catalyst for the aerobic oxidation of benzyl alcohol

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