Copper complexes three-coordinate

The reaction of metallic copper with thiuram disulfides yields complexes of Cu I), which are polymeric in solution as well as in the solid state 121,122). In 123) the copper atoms are located at the corners of a slightly distorted tetrahedron with Cu—Cu distances ranging from 2.6—2.7 A. Each of the copper atoms is coordinated to three sulfur atoms in a nearly planar triangular arrangement and each sulfur atom coordinates one or two copper atoms. 

The material included in this chapter has been organized by oxidation state, with further subdivision into ligand donor type, and was obtained from reports published in primary research journals. The article will cover coordination complexes of copper in three oxidation states Cum, Cu11, and Cu1. The sections dealing with specific ligand donor types cut across several structural types. In view of the all-inclusive nature of the previous review of CCC(1987), no effort will be made here to present a comprehensive account. Instead, specific cases will be chosen for discussion because they exemplify important concepts concerning the relationship of ligand structure to metal complex properties. 

Using 1,4,8,11-tetraazacyclotetradecane, the structure of complex (800) (distorted trigonal planar Cu-Cu 6.739 A) was determined. Reactivity with 02 was investigated to demonstrate the formation of trans-l,2-peroxo species.585 As part of their work with copper(I) complexes with 02, the structure of a dicopper(I) complex ((801) distorted tetrahedral 7.04 A), supported by macrocyclic ligand environment, was reported by Comba and co-workers. Tolman and co-workers structurally characterized a three-coordinate copper(I)-phenoxide complex (802) (planar T-shaped) that models the reduced form of GO.587 The copper(I) analogue [Cu(L)][CF3-SO3]-0.43MeOI I (803) of a copper(II) complex (534) was also reported to demonstrate the role of ligand framework conformability in CV /Cu1 redox potentials.434 Wilson and co-workers... 

A combination of the SNAr feature and the coordination ability of a copper complex has led to the development of a new O-arylation method that makes use of a triazene as an activating and directing group (Equation (2)).32,33 This protocol, though necessitating a three-step removal sequence of the triazene moiety, has been successfully applied to the total synthesis of vancomycin1 6 and extended to a solid-phase synthesis in which the triazene unit serves as an anchor to the resin.37... 

Three major approaches have been followed to provide reactive dyes in this important sector. One category is closely related to the reddish blue monoazo 1 1 copper complexes already described (section 7.5.8). To provide the higher substantivity and deeper intensity for build-up to navy blue shades, a second unmetallised azo grouping is introduced. As with the brown dyes, the A—>M—>E pattern is adopted for their synthesis. Component A is normally a sulphonated aniline, M an aminophenol or aminocresol and E a sulphonated naphthol or aminonaphthol. The reactive system (Z) is usually, but not invariably, located on the E component and the copper atom always coordinates with an o,o -dihydroxyazo grouping provided by the M and E components (7.109). 

The complexation of anionic species by tetra-bridged phosphorylated cavitands concerns mainly the work of Puddephatt et al. who described the selective complexation of halides by the tetra-copper and tetra-silver complexes of 2 (see Scheme 17). The complexes are size selective hosts for halide anions and it was demonstrated that in the copper complex, iodide is preferred over chloride. Iodide is large enough to bridge the four copper atoms but chloride is too small and can coordinate only to three of them to form the [2-Cu4(yU-Cl)4(yU3-Cl)] complex so that in a mixed iodide-chloride complex, iodide is preferentially encapsulated inside the cavity. In the [2-Ag4(//-Cl)4(yU4-Cl)] silver complex, the larger size of the Ag(I) atom allowed the inner chloride atom to bind with the four silver atoms. The X-ray crystal structure of the complexes revealed that one Y halide ion is encapsulated in the center of the cavity and bound to 3 copper atoms in [2-Cu4(//-Cl)4(//3-Cl)] (Y=C1) [45] or to 4 copper atoms in [2-Cu4(/U-Cl)4(/U4-I)] (Y=I) and to 4 silver atoms in [2-Ag4(/i-Cl)4(/i4-Cl)] [47]. NMR studies in solution of the inclusion process showed that multiple coordination types take place in the supramolecular complexes. 

Turning to the X-ray absorption edge spectrum of the T3 site In T2D laccase (Figure 10a), a peak Is observed below 898A eV. This energy Is characteristic of Cu(I) while the shape of the peak suggests that It is due to three coordinate copper. The amount of reduced copper present can then be quantitated from the normalized edge intensities of copper model complexes with the appropriate... 

Figure 14.4 The three forms of the copper-complexed catenane, each species being either a monovalent or a divalent complex, (a) Four-coordinate complex, (b) five-coordinate complex, and (c) six-coordinate complex.

In the solid state the stereochemistry of copper(I) in its mononuclear complexes, as determined by X-ray crystallography (Figure 4.1), is dominated by four coordination. A significant number of three- and two-coordinate complexes are known, very few five-coordinate complexes exist and six coordination (or above) is unknown. This contrasts with the predominance of six coordination in the chemistry of copper(II) (see Section 53.4.2) and the absence of two or three coordination in the solid state, and with the formation of a significant number of seven- and eight-coordinate geometries.47,48... 

Table 6 Copper(I) Mononuclear Three-coordinate Complexes...

Copper and nickel complexes of the tridentate l-(2-carboxyphenyl)-3,5-diphenyl- (169 X = C02 R = R = Ph) and 1-(2-hydroxyphenyl)-3,5-diphenyl-(169 X = 0 R = R = Ph) formazans were prepared118 by the interaction of the formazan and the appropriate metal acetate in alcohol and were assigned the three-coordinate structures (170 X = O, C02 R = R = Ph M = Ni, Cu) since the diamagnetic nickel complexes were found to be unimolecular in benzene solution. Treatment of the nickel complex (170 X = O, R = R = Ph M = Ni) with pyridine gave a violet crystalline adduct which was assigned the four-coordinate structure (171 X = O R = R = Ph M = Ni). A product similar to the latter could not be obtained from the nickel complex of l-(2-carboxyphenyl)-3,5-diphenylformazan but nickel complexes of this type were obtained from both l-(2-hydroxyphenyl)- (169 X = O, R = CN R = Ph) and l-(2-carboxyphenyl)- (169 X = C02 R = CN R = Ph) 3-cyano-5-phenylformazans. In all three cases a considerable shade change occurred on going from the three-coordinate complex to the pyridine adduct. 

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