Group 6 carbonyl complexes of N,O,P-ligands as precursors of high-valent metal-oxo catalysts for olefin epoxidation

resumo

The metal-catalyzed epoxidation of olefins is an important reaction in organic synthesis, as epoxides are useful intermediates for the production of bulk and fine chemicals. Molybdenum complexes are known as effective catalysts for selective epoxidation with alkyl hydroperoxides as oxidants. Very early on, it was recognized that molybdenum hexacarbonyl could be used directly as a catalyst precursor, being con-verted in situ to a soluble MoVI active species. In recent years this field has expanded greatly with the study of a wide range of group 6 carbonyl complexes as precursors to catalysts and/or functional metal oxides. In this review, pioneering work on the use of group 6 hexacarbonyls, mainly Mo(CO)6, as pre-catalysts is summarized, followed by a comprehensive analysis of recent research in which heteroleptic complexes of the type [Mo(CO)x(L)n] (x = 3 or 4; n = 1 or 3) and [MXm(CO)3(L)n] (M = Mo, W; X = halide; m = 1 or 2; n = 1 or 2) were employed, where L is a N-, O-or P-donor ligand. The topics covered include precursor synthesis and structural chemistry, solvent, oxidant and ligand effects, catalytic applications for the valorization of functionalized and nonfunctionalized olefins, catalyst activation and mechanistic studies. Current understanding about the oxidation of the heteroleptic Mo0/II complexes to oxomolybde-num complexes or hybrid materials is discussed, with a review of the behavior of these compounds as (pre)catalysts for homogeneous or heterogeneous olefin epoxidation.(c) 2022 The Author(s). Published by Elsevier B.V. This is an open access article under the CC BY license (http://creativecommons.org/licenses/by/4.0/).

palavras-chave

MICROWAVE-ASSISTED SYNTHESIS; TERT-BUTYL HYDROPEROXIDE; MO(II) COMPLEXES; MOLYBDENUM(VI) COMPLEXES; TETRACARBONYL COMPLEXES; ORGANIC HYDROPEROXIDES; ALKYL HYDROPEROXIDES; CRYSTAL-STRUCTURES; ELECTROCHEMICAL SYNTHESIS; PYRAZOLYLPYRIDINE LIGAND

categoria

Chemistry

autores

Bruno, SM; Valente, AA; Gonçalves, IS; Pillinger, M

Grupos

G1 - Materiais Porosos e Nanossistemas
G4 - Materiais Renováveis e Economia Circular

Projectos

Collaboratory for Emerging Technologies, CoLab (EMERGING TECHNOLOGIES)

CICECO - Aveiro Institute of Materials (UIDB/50011/2020)

CICECO - Aveiro Institute of Materials (UIDP/50011/2020)

Associated Laboratory CICECO-Aveiro Institute of Materials (LA/P/0006/2020)

Sistemas ativados por estímulos para a terapia com monóxido de carbono (SASCOT)

Conversao catalitica de olefinas derivadas da biomassa (BiOle_AcidOxCat)

agradecimentos

We acknowledge support and funding provided within the project CICECO - Aveiro Institute of Materials [FCT (Fundacao para a Ciencia e a Tecnologia) ref. UIDB/50011/2020, UIDP/50011/2020 and LA/P/0006/2020], the CENTRO 2020 Regional Operational Programme (project references CENTRO-01-0145-FEDER-028031 and PTDC/QUIQOR/28031/2017), and the COMPETE 2020 Operational Thematic Program for Competitiveness and Internationalization (POCI-01-0145-FEDER-030075), co-financed by national funds through the FCT/MEC (Ministerio da Educacao e Ciencia) and the European Union through the European Regional Development Fund under the Portugal 2020 Partnership Agreement.