Dioxygen Activation Using Schiff Base Macrocyclic Dinuclear Copper( I ) Complexes: Structurally Characterized Dioxygen Reaction Products

Reactivity of Copper Complexes with Bis(piperidinyl)methane and Bis(quinolinyl)methane Ligands

“…Although the copper(I) ions were oxidized to copper(II) ions, no effects on the ligand were observed. This coordination motif is quite usual (only a few examples are given in the references) and is observed if a ligand hydroxylation does not occur. Depending on the solvent, the formation of similar bis(µ‐hydroxido)copper complexes is possible, as well , …”

Bispidine Coordination Chemistry

“…These include the reduced Cu(I)Cu(I) state with a bridging water and a Cu-Cu distance of 4.4 Å (deoxy), the oxidized Cu(II)Cu(II) form with a hydroxo bridge and a Cu-Cu distance of 2.9 Å (met), and an intermediate Cu(II)Cu(II) form with a bound catechol model substrate (the inhibitor phenylthiourea), coordinated as a monodentate ligand to one of the copper centers with a Cu-Cu distance of 4.2 Å (277). A number of low molecular weight model systems have been described, and relevant experimental structural data have been obtained for the dicopper(I) (289)(290)(291)(292), the m-peroxo dicopper(II) (280), the m-Z 2 :Z 2 -peroxo dicopper(II) (269), the bis-m-oxo-dicopper(III) (293), the m-hydroxo-dicopper(II) (289), and various dicopper(II) catecholate complexes with bridging catecholate (192,294), monodentate and various forms of chelating catecholate bound to one copper center (these generally have the deactivated tetrachlorocatechol (tcc) coordinated as the substrate) (192). Among the most relevant high-resolution structures as models for catecholase are the first structure with a dicopper(II) center bridged with a catecholate (294), the recently published structure of the hydroxobridged-dicopper(II) met form (289), and the series of structures, which emerged from copper(II)-bispidine chemistry and includes a structure with a bridging catecholate, one with a monodentate catecholate (the first structure of that kind and a structural model for an intermediate in one of the catalytic cycles described above) and structures with two types of chelating catecholates (192), see Fig.…”

Conformational polymorphism in a Schiff-base macrocyclic organic ligand: an experimental and theoretical study

“…DIEN is an isomeric form of a hexa-aza 24-membered ring system belonging to the class of tetra-Schiff base macrocyclic organic ligands (Adams et al, 1987;Drew, 1980). The latter compounds have attracted a great deal of interest during the last decades as synthons for tyrosinase model systems (Menif et al, 1990;Martell et al, 1997;Ma et al, 2002;Utz et al, 2003). Actually, tetra-Schiff base dinuclear Cu I complexes can coordinate O 2 , promoting the regioselective oxidation of organic substrates (Martell et al, 1997) or even of the ligand itself (Menif et al, 1990).…”

“…With respect to DIEN, DIEN2 lacks the imidazolidine rings and bears two N-(CH 2 ) 2 -NH-(CH 2 ) 2 -N groups which can act as tridentate ligands towards a metal centre. Within coordination complexes, only the DIEN2 form of the ligand was observed both in solution and in the solid state (Menif et al, 1990;Adams et al, 1991;Ma et al, 2002;Utz et al, 2003), while the crystallization of the ligand alone seems to invariably lead to DIEN (Menif et al, 1990;Adams et al, 1991). However, it has to be mentioned that the crystal structure of a Ba complex with a methyl-substituted analogue of DIEN was reported several years ago (Drew, 1980).…”