Cu tetrahedra

For the Cu tetrahedra to lit into the empty spaces of the Mg pattern there must be a significant difference in the atomic diameters. In this case, the diameter ratio of the pure metals is about 3.2/2.56 = 1.25 which is just enough. Figure 8.3 is a schematic of the complete unit cell. This stmcture is often described in terms of layers lying normal to the (111) directions, but the present method is preferred by this author. 

In the same way, no evidence is found of Cu-H distances at about 1.5 distance from the center to the Cu atom in Ti3 Cu tetrahedra) despite the larger weight of the Cu-H correlations au3 conqpared to the Ti-H ones in the total pair-correlation function. This confirms the NMR results of Bowman et al. which also show that Ti tetrahedral sites are preferential... 

Fig. 17.2 The [Cu2(pzc)2(H20)2(Re04)] structure (a), with the infinite Cu(Re04) chain marked. Also, the mixed valence Cu jCu chain bonded through the pzc ligand (b). Dark polyhedra = Cu-centered light=Re04 tetrahedra.

Take the network of vertex-sharing tetrahedra of the Cu atoms in MgCu2 (Fig. 15.4) and assume that there is an additional atom inside of every tetrahedron. What structure type would this be ... 

Cu Mo30jj(x = 0.15) M0O4 in fairly regular tetrahedra CuOg ... 

Tetrammino-cupric Iodide Monohydrate, [Cu(NH3)4]I2.H20, crystallises in dark blue tetrahedra and decomposes rapidly in air, with loss of ammonia and formation of a dark brown compound. If the solution of the salt in ammonia be warmed it changes in colour, and, on cooling, crystals of decammino-tricupric iodide, [Cu3(NII3 separate. This substance on heating is transformed into diammino-eupric iodide. 

The only reported discrete trinuclear halogenocuprate(I) species composed of four-coordinated metal(I) centers is [Cu3l6]3-, which contains three face-sharing copper(I) iodide tetrahedra (91,95). Terminal Cu—I bonds are 2.505(5) and 2.519(6) A, whereas bridging Cu—I bonds range from 2.529(6) to 3.205(8) A the face sharing of tetrahedra results in very short Cu—Cu contacts [2.518(6) and 2.519(6) A] involving the middle copper(I) center (95). 

Recently, evidence has been provided for the existence of polymeric [Agl2] ions in fairly concentrated solutions of sodium diiodoar-gentate(I) in acetonitrile (119). In bis(2,2-bipyridyl)copper(II) bis[dich-lorocuprate(I) ] (24), the polymeric anion is composed of pairs of edgesharing tetrahedra linked via linear Cl—Cu—Cl units (see Section II,A,2). 

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