Dicopper complexes, bridged

A further extension of m-xylyl dicopper complexation and xylyl hydroxy la-tion is seen in a Schiff-base macrocycle [175], When dicopper(I) complex 38 is reacted with 02, one of the two arene rings is hydroxylated, again producing a phenoxo-bridged dicopper(II) species a peroxo-dicopper(II) intermediate is suggested as the actual oxidant. 

This chapter focuses on the chemistry ofbiomimetic copper nitrosyl complexes relevant to the NO-copper interactions in proteins that are central players in dissimilatory nitrogen oxide reduction (denitrification). The current state of knowledge of NO-copper interactions in nitrite reductase, a key denitrifying enzyme, is briefly surveyed the syntheses, structures, and reactivity of copper nitrosyl model complexes prepared to date are presented and the insight these model studies provide into the mechanisms of denitrification and the structures of other copper protein nitrosyl intermediates are discussed. Emphasis is placed on analysis of the geometric features, electronic structures, and biomimetic reactivity with NO or NOf of the only structurally characterized copper nitrosyls, a dicopper(II) complex bridged by NO and a mononuclear tris(pyrazolyl)hydroborate complex having a Cu(I)-NO formulation. 

Molecular mechanics studies of a series of dicopper complexes of a 20-membered macrocycle containing differing types of bridges between the metal centers, M. G. B. Drew and P. C. Yates, J. Chem. Soc., Dalton Trans., 1987, 2563. 

The closely related oxygen-bridged dicopper complexes based on /3-enaminoketones were also studied ((280) X = H, n= 12, 14, 16, 18). They exhibited an enantiotropic SmA phase typically between the melting point in the range 145-150 °C and the clearing point in the range 160-180 °C. 

Figure 12 Phenoxo-bridged dicopper complex (a) and a portion of the 2D square grid structure (b) in 82.

With a dicopper complex bearing bis-imidazole ligands (Figure 25d), a strong cooperativity was observed for the 1,3 distal complex. The suggested mechanism involved double activation of the bridging phosphoryl function, followed by nucleophilic attack assisted by the coordinated hydroxide. ... 

In 1984, Valentine reported that an iodosylbenzene might be capable of bridging two Cu(II) ions via its oxygen atom, and that such a complex might lose Phi to generate an active [Cu -0-Cu ] species [32]. A dicopper complex was later found to react with PhIO to produce a new complex that slowly releases Phi [33]. This adduct, in the presence of excess cyclohexene, yielded significant amounts of the corresponding epoxide. 

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