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Coordination Chemistry of 1,3‐Bis(2‐pyridylimino)‐ and 1,3‐Bis(2‐thiazolylimino)soindole Copper Complexes: Investigation of Their Catalytic Behavior in Oxidation Reactions
Author(s) -
Meder Markus B.,
Gade Lutz H.
Publication year - 2004
Publication title -
european journal of inorganic chemistry
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.667
H-Index - 136
eISSN - 1099-0682
pISSN - 1434-1948
DOI - 10.1002/ejic.200400012
Subject(s) - chemistry , cyclohexene , monoclinic crystal system , copper , trigonal bipyramidal molecular geometry , square pyramidal molecular geometry , crystal structure , coordination geometry , orthorhombic crystal system , crystallography , coordination complex , catalysis , monomer , allylic rearrangement , ligand (biochemistry) , coordination polymer , polymer chemistry , molecule , organic chemistry , polymer , metal , hydrogen bond , receptor , biochemistry
The copper complexes [Cu(4‐MeBPI)(OAc)] ( 4 ), [Cu(4‐Me‐10‐ t BuBPI)(OAc)] ( 5 ) and [Cu(BTI)(OAc)] ( 6 ) [BPI = 1,3‐bis(2‐pyridylimino)isoindole, BTI = 1,3‐bis(2‐thiazolylimino)isoindole] were prepared by reaction of the protio ligands with copper( II ) acetate. Compounds 4 and 6 were characterized by X‐ray diffraction, establishing distorted square‐planar coordination geometries of the copper ions. Two monoclinic modifications of 6 ( 6a and 6b ) were found, both crystallizing in the space group P 2 1 / c , but possessing different cell parameters. In contrast to 6a , which is monomeric in the crystal, the second monoclinic modification 6b has a more complicated crystal structure, which is composed of both monomeric complex units such as those found in 6a and infinite chains of coordination polymers. The copper atoms in the polymeric chains of 6b display fivefold coordination and a ligand polyhedron that is an intermediate form between a trigonal‐bipyramidal and a square‐pyramidal geometry. The allylic peroxylation of cyclohexene with t BuOOH (70% aqueous solution) catalyzed by 4 and 6 (0.17 mol %) gave tert ‐butylperoxy‐3‐cyclohexene with selectivities of 86% and 80% (based on cyclohexene) and turnover frequencies of 63 h −1 and 18 h −1 , respectively. The peroxylation reaction is thought to proceed according to a Haber−Weiss radical chain mechanism. (© Wiley‐VCH Verlag GmbH & Co. KGaA, 69451 Weinheim, Germany, 2004)