A Paramagnetic Copper(III) Complex Containing an Octahedral CuIIIS6 Coordination Polyhedron

Abstract

Only the second octahedral, paramagnetic copper(III) complex (S=1) has now been synthesized and characterized. Six thiolato bridging ligands in the heterotrinuclear species [LCo Cu Co L](ClO ) ⋅2 Me CO (L=1,4,7-tris(4-tert-butyl-2-sulfidobenzyl)-1,4,7-triazacyclononane) stabilize this rare electron configuration. A section of the structure of the reduced form (Cu , S=½) is shown. XAS, EXAFS, and EPR spectroscopy prove unambiguously that the one-electron oxidation to the copper(III) is metal- rather than ligand-centered.

Mechanistic Studies of Ullmann‐Type C–N Coupling Reactions: Carbonate‐Ligated Copper(III) Intermediates

“…In toluene, 5 b shows absorptions at λ 1 =1058, 1020 ( 3 A 2g → 3 T 2g ), λ 2 =910, 874 ( 3 A 2g → 3 T 1g , F), and λ 3 =474 nm ( 3 A 2g → 3 T 1g , P). A doublet ( λ =714, 730 nm) is attributed to forbidden transition 3 A 2g → 1 E 1g . No shift in the position of the absorption bands was observed by exchanging 2 b with 2 c .…”

Electron-rich salen-type Schiff base complexes of Cu(II) as catalysts for oxidation of cyclooctene and styrene with tert-butylhydroperoxide: A comparison with electron-deficient ones

“…The improved selectivity of reaction as well as the efficiency of the title catalysts may be resulted in by the presence of electron-donating groups at aryl rings of the title Schiff bases. Electron-donor substituents seems to facilitate the oxidation of Cu(II) to Cu(III) [30][31][32]. It should be noted that the oxidation of Cu(II) to Cu(III) has been proposed as an important step in the Cu-salen catalyzed oxidation of hydrocarbons with TBHP (Scheme 1) [9].…”

Diamagnetic–Paramagnetic Conversion of Tris(2‐pyridylthio)methylcopper(III) through a Structural Change from Trigonal Bipyramidal to Octahedral

“…The CuC(sp 2 ) bonds in the N‐confused porphyrins are stabilized by the π‐delocalization effect in the porphyrin ring aided by protonation–deprotonation of the peripheral nitrogen atoms 8. Nonplanar Cu III complexes are rare, and only a few structures have been reported,3 namely square‐pyramidal [Cu(PhCO 2 ) 2 (pyridine) 2 Cl]9 and an octahedral moiety in a Co III Cu III Co III heterometallic cluster bridged by 1,4,7‐tris(4‐ tert ‐butyl‐2‐sulfidobenzyl)‐1,4,7‐triazacyclononane 10…”