Copper linearly-coordinated

Polymeric complexes are formed when copper(I) chloride reacts with dialkylhydrazines (105) or with 3,5,5-trimethylpyrazolidine. In Cu2Cl2(MeN=NMe) the structure consists of parallel Cl-Cu-Cl chains cross-linked by weak Cu-Cl bonds and strong Cu-N a bonds (47). Structures of CuI(PhN=NH) and Cu4Cl4(PhN=NH) may be similar (282, 290). Diazoaminobenzene copper(I) (110, 245) can be prepared from copper and the ligand it is dimeric with each copper linearly coordinated to 1,1 iV or 3,3 N atoms (48). The cation in [Cu(PhN2Ph)]-CIO4 may have a related structure (265). 

The complexes of copper(I) like those of silver(I) (p. 430), but unlike those of preceding transitions metals, tend to prefer a linear coordination of two ligands, i.e. X—Cu—X thus copper(I) chloride in aqueous ammonia gives the colourless [Cu(NH3)2] (readily oxidised in air to give blue [Cu (NH3)4(H20)2] copper(I) chloride in hydrochloric acid gives [CuClj], although [CuCl3] is also known. 

All three M+ ions are known to form compounds with the unusual digonal linear coordination (see also section 4.9.7), though this is most common for gold. As a result, complexes R3PMX of copper and silver are normally di-and tetranuclear species with 3- or 4-coordinate metals, while the gold analogues are 2-coordinate monomers. This is the reverse of what would be expected on steric grounds [13, 14],... 

The copper-alkoxo unit, which is usually synthesized in situ, plays a significant role in metal-promoted transformations of organic substrates by copper(I). To determine the reaction form of the Cu-OPh unit, Floriani and co-workers structurally characterized four complexes (772) (pseudotetrahedral Cu-Cu 3.223 AT (773) (pseudotetrahedral), (774) ( anion linear coordination) and (775) (planar trigonal).57 Using 3,3,6,6-tetramethyl-l-thia-4-cycloheptyne as terminal ligand the structural characterization of a copper(I)-alkyne complex (776) (Cu-Cu 2.940 A) was reported.573... 

Figure 4 Polarization of the cores of Bi111 and Cu1. Oxygen ligands are unable to form strong bonds using the empty Cu 4s or Bi 6p orbitals due to interference of the 3d or 6s cores. Core polarization, d-s, for copper solves this problem and gives two-fold linear coordination for Cu1 and other d10 cations such as Ag1 and Hgn. Core polarization, s-p, for bismuth results in strong bonds on one side of Bi111 and weak bonds on the opposite side.

The cuprite (CujO) structure consists of a body-centred cubic array of oxygen the copper atoms occupy centres of four of the eight cubelets into which the BCC cell may be divided (Fig. 1.7). In this structure, copper has a linear coordination and oxygen tetrahedral coordination (2 4). This structure is unique among inorganic materials in that it consists of two identical interpenetrating frameworks which are not directly linked to each other. 

Several metals bind at the vacant copper site of apoazurin, including Ni11 and Co11,928 and, less usually, gold.929 There were some differences between the H NMR spectra of the copper and gold azurins, notably in the methionine S—Me region. Au1 prefers linear coordination. 

That subtle variations in the ligand system can have a large influence on the overall structure of the copper compound is also attested to by the different structures of [Cu(MesSiCH(Py-2))]4 (Py-2 = 2-pyridyl) and [Cu((MejSi)2C(Py-2))]2. In both compounds, the 2-methylpyridyl group is -bonded to a copper atom, while a linear coordination geometry at the copper center is achieved throu inter-molecular coordination of the nitrogen atom of an adjacent pyridyl unit. However [Cu(MejSiCH(Py-2))]4 exists as a tetramer in solution and in the solid state [68], whereas [Cu((MejSi)2C(Py-2))]2 has a dimeric structure (see Fig. 1.11) [68, 69]. This difference is probably a consequence of the presence of a second bulky Me Si substituent at the carbon atom bound to copper in [Cu((Me5Si)2C(Py-2))]2. 

A similar species distribution is found for [(en)Pd(OH)2]/erythritol solutions, and a crystal stracture containing a binuclear complex analogous to 9 has been determined [19]. A solid-state structure of this type is also formed by ethylenediamine-copper(II) [20]. In strong alkaline aqueous solutions, the ethylenediamine-copper bond is cleaved and the formation of homolep-tic complexes such as the linear coordination polymer 10 (O Fig. 1) is enabled [21]. 

In 1994, the ab initio X-ray crystal stucture determination from powder diffraction data of [Cu(pz)] and [Ag(pz)] were reported (13). During these studies it was ascertained that copper(I) and silver(I) pyrazolates, depending on the synthetic method used, each appear in two distinct crystalline phases. The a-[Cu(pz)] , 2a, and /3-[Cu(pz)] , 2b, consist of infinite chains of linearly coordinated copper atoms, bridged by exo-bidentate pyrazolate anions (Fig. 2). The two phases differ mainly in the interchain Cu- -Cu contacts, which are 3.34 A in a-[Cu(pz)] and 2.97 A in 3-[Cu(pz)] . 

Cuprous Complexes.3 With simple ligands (e.g., halide ions, amines), the coordination is almost invariably tetrahedral. No discrete 2- or 3-coordinate species have been found in solids (contrast with Ag1 and Au1), although linear 2-coordination is found in Cu20 and KCuO. KCu(CN)2 contains no linear Cu(CN)2 ion (as do its Ag1 and Au1 analogs), but instead it has a spiral polymeric structure in which each Cu1 atom is bound to two CN-carbon atoms and one CN-nitrogen atom in a nearly coplanar array (see Fig. 25-H-l). In the (l,3-dimethyltriazeno)copper(i) complex each copper atom is linearly coordinated by two nitrogen atoms (25-H-I) and there is... 

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