Six-coordinate stereochemistry

The stereochemistry and electronic properties of fluxional six-coordinate copper(II) complexes. B. Hathaway, M. Duggan, A. Murphy, J. Mullane, C. Power, A. Walsh and B. Walsh, Coord. Chem. Rev., 1981,36, 267-324 (132). 

Site symmetry symbols, I, 128 Six-coordinate compounds stereochemistry, 1, 49-69 Six-membered rings metal complexes, 2, 79 Skeletal muscle sarcoplasmic reticulum calcium pump, 6, 565 Slags... 

All these methods have found applications in theoretical considerations of numerous problems more or less directly related to solvent extraction. The MM calculated structures and strain energies of cobalt(III) amino acid complexes have been related to the experimental distribution of isomers, their thermodynamic stability, and some kinetic data connected with transition state energies [15]. The influence of steric strain upon chelate stability, the preference of metal ions for ligands forming five- and six-membered chelate rings, the conformational isomerism of macrocyclic ligands, and the size-match selectivity were analyzed [16] as well as the relation between ligand structures, coordination stereochemistry, and the thermodynamic properties of TM complexes [17]. 

Alexander and Gray 70) and Caulton 71) have studied the electronic spectrum of the species [Co(CN)5] . Although direct proof is lacking, it has been affirmed that the optical and E. P. R. spectra are consistent with an essentially square p5u-amidal stereochemistry and are inconsistent with a trigonal bipyramidal structure (70). It has been claimed, however, that this species may be actually six-coordinate in water, i. e. [Co(CN)5(H20)]3- (72). The spectrum of [Co(CN)5]3. has four bands of low intensity between 10 and 32 kK, as well as two high intensity bands at higher frequence (Table 7). 

The stereochemistry of molecular six-coordinated dimethyltin derivatives can vary substantially from the cis [SnQQj geometry (71), adopted by dimethyltin bis(oxinate)441 and... 

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... 

Five-coordination is as abundant in copper(II) complexes as the six-coordinate elongated rhombic octahedral stereochemistry (Figure 19.1). The regular square-based pyramidal geometry with five equivalent ligands is only of limited occurrence, but does arise in... 

The observation of temperature variable structures for six-coordinate copper(II) complexes involving tetragonalities greater than 0.85 enables the various stereochemistries of Figure 19 to be subdivided into their temperature variable and non-temperature-variable stereochemistries,396 as summarized in Table 29. In this sense they may be divided into the static and nonstatic stereochemistries of the copper(II) ion, but it should always be remembered that 95% of the observed structures of the copper(II) ion involve static stereochemistries, which are non temperature variable. 

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