Abstract
Copper(I) halides dissolve in deoxygenated methylene chloride and nitrobenzene solutions of equimolar N,N,N′-triethylethylenediamine (TriEED) to give air-sensitive colorless or pale yellow copper(I) dimers [(TriEED)(μ-X)Cu]
2
, X = Cl, Br or I. Dioxygen uptake, analytical, cryoscopic and spectral data show that copper(I) dimers are oxidized to μ-oxo complexes, [(TriEED)
2
(μ-X)
2
(μ-O)Cu
2
], which react with carbon dioxide to form μ-carbonato analogues, [(TriEED)
2
X
2
(μ-CO
3
)Cu
2
]. Both oxo and carbonato complexes are homogeneous oxidative coupling catalysts for oxidation of 2,6-dimethylphenol to mixture of diphenoquinone (DPQ) and polyphenyleneoxide (PPO). Kinetic data for oxidation of [(TriEED)(μ-X)Cu]
2
by dioxygen in nitrobenzene obey the third-order rate law d[[(TriEED)
2
(μ-X)
2
(μ-O)Cu
2
]]/dt = k
D
[[(TriEED)(μ-X)Cu]
2
]
2
[O
2
]. Comparison of the kinetic data with data for oxidation of [(TEED)(μ-Br)Cu]
2
, TEED = N,N,N′,N′-tetraethylethylenediamine (the fully alkylated diamine), by dioxygen indicate that N-H in (TriEED) speeds the reaction by a factor of 220 due to an intermolecular attractive force between N-H of (TriEED) and the incoming dioxygen, helping to assemble the activated complex.