abstract
The chemistry and catalytic performance of the dichlorido complex [MoO2Cl2(pbim)] (1) [pbim = 2-(2-pyridyl)benzimidazole] in the epoxidation of olefins is reported. Complex 1 acts as a precatalyst and is more effective with tert-butyl-hydroperoxide (TBHP) as the oxidant than with aq. hydrogen peroxide: the cis-cyclooctene (Cy) reaction with TBHP gave 98 % epoxide yield at 70 degrees C/24 h. Catalyst characterization showed that 1 is transformed in situ to the oxidodiperoxido complex [MoO(O-2)(2)(pbim)] (2), with H2O2 and a hybrid molybdenum(VI) oxide solid formulated as [MoO3(pbim)] (3) with TBHP. The hybrid material 3 was prepared on a larger scale and explored for the epoxidation of the biorenewable olefins methyl oleate, methyl linoleate, and (R)-(+)-limonene. With TBHP as the oxidant, 3 acts as a source of soluble active species of the type 2. A practical method for recycling oxidodiperoxidomolybdenum(VI) catalysts for the Cy/TBHP reaction is demonstrated by using an ionic liquid as the solvent for the molecular catalyst 2.
keywords
OXO-MOLYBDENUM COMPLEXES; METAL-ORGANIC FRAMEWORK; OLEFIN EPOXIDATION; STRUCTURAL ELUCIDATION; EFFICIENT CATALYSTS; DIOXOMOLYBDENUM(VI)-BIPYRIDINE COMPLEXES; HYDROTHERMAL SYNTHESIS; RHENIUM COMPLEXES; PEROXO COMPLEXES; DIOXO COMPLEXES
subject category
Chemistry
authors
Neves, P; Nogueira, LS; Gomes, AC; Oliveira, TSM; Lopes, AD; Valente, AA; Goncalves, IS; Pillinger, M
our authors
Ana Catarina Costa Gomes Alves
Assistant Researcher
Anabela Tavares Aguiar Valente
Principal Researcher
Isabel Maria de Sousa Gonçalves
Associate Professor
Lucie Solange Nogueira
PhD Student
Martyn Pillinger
Principal Researcher
Patrícia dos Santos Neves
Assistant Researcheracknowledgements
This work was developed in the scope of the project CICECO - Aveiro Institute of Materials (POCI-01-0145-FEDER-007679) financed by national funds through the Fundacao para a Ciencia e a Tecnologia (FCT) (ref. UID/CTM/50011/2013) and Ministerio da Educacao e Ciencia (MEC) and when applicable, cofinanced by Fundo Europeu de Desenvolvimento Regional (FEDER) under the PT2020 Partnership Agreement. The FCT and the European Union are acknowledged for a Ph.D. grant to L. N. (PD/BD/109666/2015), and post-doctoral grants to P. N. (SFRH/BPD/110530/2015) and A. C. G. (SFRH/BPD/108541/2015), cofunded by Ministerio da Ciencia, Tecnologia e Ensino Superior (MCTES) and the European Social Fund through the program Programa Operacional Potencial Humano (POPH) of Quadro de Referencia Estrategica Nacional (QREN).