Oxidation of alkylbenzenes with cerium complexes containing a tripodal oxygen ligand

Xiao Yi Yi; Guo Cang Wang; Ho Fai Ip; Wai Yeung WONG; Lizhuang Chen; Herman H.Y. Sung; Ian D. Williams; Wa Hung Leung

doi:10.1002/ejic.201402772

Oxidation of alkylbenzenes with cerium complexes containing a tripodal oxygen ligand

Xiao Yi Yi, Guo Cang Wang, Ho Fai Ip, Wai Yeung WONG, Lizhuang Chen, Herman H.Y. Sung, Ian D. Williams, Wa Hung Leung^*

^*Corresponding author for this work

Department of Chemistry

Research output: Contribution to journal › Journal article › peer-review

13 Citations (Scopus)

Abstract

The treatment of [Ce(L_OEt)₂(NO₃)₂] (L_OEt^- = [Co(η⁵-C₅H₅){P(O)(OEt)₂}₃]^-) with KMnO₄ in water afforded a diamagnetic purple solid 1, which is tentatively formulated as a Ce^IV permanganate complex, "[Ce(L_OEt)₂(MnO₄)₂]". The Zr^IV analogue, [Zr(L_OEt)₂(MnO₄)₂] (2), has been prepared similarly from [Zr(L_OEt)₂(NO₃)₂] and KMnO₄. The recrystallization of 1 from CH₂Cl₂/hexanes at -18 C led to the isolation of dinuclear [(CeL_OEt)₂(μ-L_OEt′)₂][MnO₄]₂ (3), which contains the dianionic tripodal ligand [L_OEt′]^2- ([(η⁵-C₅H₅)Co{P(O)(OEt)₂}₂{P(O)₂(OEt)}]^2-). The reactions of 1 with K[ReO₄] and [NH₄][OsO₃N] afforded the heterodimetallic complexes [Ce(L_OEt)₂(ReO₄)₂] (4) and [Ce(L_OEt)₂(NOsO₃)₂] (5), respectively. The crystal structures of 3 and 5 have been determined. Freshly prepared 1 can oxidize alkylbenzenes such as toluene, ethylbenzene, and cumene at room temperature to give the corresponding ketone and/or alcohol products. Ce-L_OEt complexes are efficient promoters of the aerobic oxidation of alkylbenzenes by a radical mechanism. For example, cumene in the presence of [Ce(L_OEt)₂(H₂O)₂]Cl (1 mM) in air at 100 C for 10 h afforded a ca. 6:1 mixture of 2-phenyl-2-propanol and acetophenone with a total turnover number of 6810.

Original language	English
Pages (from-to)	6097-6103
Number of pages	7
Journal	European Journal of Inorganic Chemistry
Volume	2014
Issue number	35
DOIs	https://doi.org/10.1002/ejic.201402772
Publication status	Published - Dec 2014

Scopus Subject Areas

Inorganic Chemistry

User-Defined Keywords

Alkylbenzenes
Cerium
Heterometallic complexes
O ligands
Oxidation

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10.1002/ejic.201402772

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@article{a3181411efd9452ab40e312afd7799c3,

title = "Oxidation of alkylbenzenes with cerium complexes containing a tripodal oxygen ligand",

abstract = "The treatment of [Ce(LOEt)2(NO3)2] (LOEt- = [Co(η5-C5H5){P(O)(OEt)2}3]-) with KMnO4 in water afforded a diamagnetic purple solid 1, which is tentatively formulated as a CeIV permanganate complex, {"}[Ce(LOEt)2(MnO4)2]{"}. The ZrIV analogue, [Zr(LOEt)2(MnO4)2] (2), has been prepared similarly from [Zr(LOEt)2(NO3)2] and KMnO4. The recrystallization of 1 from CH2Cl2/hexanes at -18 C led to the isolation of dinuclear [(CeLOEt)2(μ-LOEt′)2][MnO4]2 (3), which contains the dianionic tripodal ligand [LOEt′]2- ([(η5-C5H5)Co{P(O)(OEt)2}2{P(O)2(OEt)}]2-). The reactions of 1 with K[ReO4] and [NH4][OsO3N] afforded the heterodimetallic complexes [Ce(LOEt)2(ReO4)2] (4) and [Ce(LOEt)2(NOsO3)2] (5), respectively. The crystal structures of 3 and 5 have been determined. Freshly prepared 1 can oxidize alkylbenzenes such as toluene, ethylbenzene, and cumene at room temperature to give the corresponding ketone and/or alcohol products. Ce-LOEt complexes are efficient promoters of the aerobic oxidation of alkylbenzenes by a radical mechanism. For example, cumene in the presence of [Ce(LOEt)2(H2O)2]Cl (1 mM) in air at 100 C for 10 h afforded a ca. 6:1 mixture of 2-phenyl-2-propanol and acetophenone with a total turnover number of 6810.",

keywords = "Alkylbenzenes, Cerium, Heterometallic complexes, O ligands, Oxidation",

author = "Yi, {Xiao Yi} and Wang, {Guo Cang} and Ip, {Ho Fai} and WONG, {Wai Yeung} and Lizhuang Chen and Sung, {Herman H.Y.} and Williams, {Ian D.} and Leung, {Wa Hung}",

year = "2014",

month = dec,

doi = "10.1002/ejic.201402772",

language = "English",

volume = "2014",

pages = "6097--6103",

journal = "European Journal of Inorganic Chemistry",

issn = "1434-1948",

publisher = "Wiley-VCH Verlag",

number = "35",

}

TY - JOUR

T1 - Oxidation of alkylbenzenes with cerium complexes containing a tripodal oxygen ligand

AU - Yi, Xiao Yi

AU - Wang, Guo Cang

AU - Ip, Ho Fai

AU - WONG, Wai Yeung

AU - Chen, Lizhuang

AU - Sung, Herman H.Y.

AU - Williams, Ian D.

AU - Leung, Wa Hung

PY - 2014/12

Y1 - 2014/12

N2 - The treatment of [Ce(LOEt)2(NO3)2] (LOEt- = [Co(η5-C5H5){P(O)(OEt)2}3]-) with KMnO4 in water afforded a diamagnetic purple solid 1, which is tentatively formulated as a CeIV permanganate complex, "[Ce(LOEt)2(MnO4)2]". The ZrIV analogue, [Zr(LOEt)2(MnO4)2] (2), has been prepared similarly from [Zr(LOEt)2(NO3)2] and KMnO4. The recrystallization of 1 from CH2Cl2/hexanes at -18 C led to the isolation of dinuclear [(CeLOEt)2(μ-LOEt′)2][MnO4]2 (3), which contains the dianionic tripodal ligand [LOEt′]2- ([(η5-C5H5)Co{P(O)(OEt)2}2{P(O)2(OEt)}]2-). The reactions of 1 with K[ReO4] and [NH4][OsO3N] afforded the heterodimetallic complexes [Ce(LOEt)2(ReO4)2] (4) and [Ce(LOEt)2(NOsO3)2] (5), respectively. The crystal structures of 3 and 5 have been determined. Freshly prepared 1 can oxidize alkylbenzenes such as toluene, ethylbenzene, and cumene at room temperature to give the corresponding ketone and/or alcohol products. Ce-LOEt complexes are efficient promoters of the aerobic oxidation of alkylbenzenes by a radical mechanism. For example, cumene in the presence of [Ce(LOEt)2(H2O)2]Cl (1 mM) in air at 100 C for 10 h afforded a ca. 6:1 mixture of 2-phenyl-2-propanol and acetophenone with a total turnover number of 6810.

AB - The treatment of [Ce(LOEt)2(NO3)2] (LOEt- = [Co(η5-C5H5){P(O)(OEt)2}3]-) with KMnO4 in water afforded a diamagnetic purple solid 1, which is tentatively formulated as a CeIV permanganate complex, "[Ce(LOEt)2(MnO4)2]". The ZrIV analogue, [Zr(LOEt)2(MnO4)2] (2), has been prepared similarly from [Zr(LOEt)2(NO3)2] and KMnO4. The recrystallization of 1 from CH2Cl2/hexanes at -18 C led to the isolation of dinuclear [(CeLOEt)2(μ-LOEt′)2][MnO4]2 (3), which contains the dianionic tripodal ligand [LOEt′]2- ([(η5-C5H5)Co{P(O)(OEt)2}2{P(O)2(OEt)}]2-). The reactions of 1 with K[ReO4] and [NH4][OsO3N] afforded the heterodimetallic complexes [Ce(LOEt)2(ReO4)2] (4) and [Ce(LOEt)2(NOsO3)2] (5), respectively. The crystal structures of 3 and 5 have been determined. Freshly prepared 1 can oxidize alkylbenzenes such as toluene, ethylbenzene, and cumene at room temperature to give the corresponding ketone and/or alcohol products. Ce-LOEt complexes are efficient promoters of the aerobic oxidation of alkylbenzenes by a radical mechanism. For example, cumene in the presence of [Ce(LOEt)2(H2O)2]Cl (1 mM) in air at 100 C for 10 h afforded a ca. 6:1 mixture of 2-phenyl-2-propanol and acetophenone with a total turnover number of 6810.

KW - Alkylbenzenes

KW - Cerium

KW - Heterometallic complexes

KW - O ligands

KW - Oxidation

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U2 - 10.1002/ejic.201402772

DO - 10.1002/ejic.201402772

M3 - Journal article

AN - SCOPUS:84916233802

SN - 1434-1948

VL - 2014

SP - 6097

EP - 6103

JO - European Journal of Inorganic Chemistry

JF - European Journal of Inorganic Chemistry

IS - 35

ER -

Oxidation of alkylbenzenes with cerium complexes containing a tripodal oxygen ligand

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