Preparation and catalytic studies of bis(halogeno) dioxomolybdenum(VI)-diimine complexes

authors	Petrovski, Z; Pillinger, M; Valente, AA; Goncalves, IS; Hazell, A; Romao, CC
nationality	International
journal	JOURNAL OF MOLECULAR CATALYSIS A-CHEMICAL
author keywords	molybdenum; nitrogen ligands; oxide complexes; olefin epoxidation; X-ray diffraction
keywords	ALKENE EPOXIDATION; ALKYL HYDROPEROXIDES; OLEFIN EPOXIDATION; OXIDATION; REACTIVITY; ADDUCTS; LIGAND
abstract	Dioxomolybdenum(VI) complexes of the type MoO(2)X(2)L containing ethylenediimine ligands were prepared in good yield by reaction of MoO(2)X(2)(THF)(2) (X = Cl, Br) with the bidentate ligands Ph(2)C=NCH(2)CH(2)N=CPh(2) (PBED) or PhCH=NCH(2)CH(2)N=CHPh (BED). The crystal structure of MoO(2)Br(2)(BED) was determined by X-ray diffraction. The dichloro complexes were active as catalysts for the reaction of cyclooctene with tert-butyl hydroperoxide (TBHP) at 55 degreesC yielding epoxycyclooctane as the only product up to 7 h after the start of the reaction. The highest initial activity was obtained with MoO(2)Cl(2)(BED) (63 mol mol(Mo)(-1) h(-1)). Other olefins were also tested, and activities decreased in the order cyclooctene > cycloclodecene > (R)-(+)-limonene > cyclohexene > trans-2-octene > 1-octene. The dibromo complexes exhibited much lower activities than the dichloro complexes for the epoxidation of cyclooctene. (C) 2004 Elsevier B.V. All rights reserved.
publisher	ELSEVIER SCIENCE BV
issn	1381-1169
year published	2005
volume	227
issue	1-2
beginning page	67
ending page	73
digital object identifier (doi)	10.1016/j.molcata.2004.10.004
web of science category	Chemistry, Physical
subject category	Chemistry
unique article identifier	WOS:000226424000009