Silver structural data

Until recently, only two reports existed for 1 1 adducts of silver halides with amines, namely AgT piperidine57 and Agl-morpholine.381 The first had a tetrameric cubane structure whilst the second was described as a stair polymer adduct. The range has now been extended to include 2-and 3-methylpyridine, quinoline and triethylamine.382 In each case the adduct was obtained by recrystallization of silver(I) iodide from neat base. The colourless crystals were found to lose base readily on exposure to the atmosphere and structural data were collected from crystals mounted in argon-filled capillaries, containing mother liquor. 

No structural data are available for silver(H) pyridine salts. Based on the evidence500 of ease of doping at all levels of the silver and copper persulfate complexes into the cadmium spedes, isomorphism was assumed. X-Ray powder photographs have since shown this not to be the case.499... 

The larger-ringed macrocycles of (53a-d) form binuclear complexes with alkali metal, alkaline earth, silver(I) and lead(II) cations.68,192 The two 18-membered rings are large enough to allow for cations as large as Rb+ to be incorporated within their cavity, with a net result of increasing the metal-metal separation. Thus, crystal structure data for the disodium complex of (53a) indicate the sodium ions to be 6.40 A apart,193,194 compared to a 3.88 A separation found for the aforementioned disilver complex of (52a). Heteronuclear complex formation has also been observed, e.g. with both Ag+ and Pb2+ incorporated in the same cryptand.192... 

Melnik and Parish (10) correlated 197Au Mossbauer and X-ray structural data for gold clusters in 1986, and Salter (11) has recently published a review of the stereochemical nonrigidity exhibited in solution by the metal skeletons of some mixed-metal clusters containing copper, silver, and gold. 

The silver halides, with the exception of one crystal modification of Agl, have cubic crystal structures. Crystal structure data, relevant lattice properties and low temperature dielectric constants, are collected in Table 3. AgF, AgCl, and AgBr all have the NaCl rocksalt structure in which there are four silver halide pairs per nonprimitive unit cell with cation-anion nearest neighbor distances equal to one-half a lattice constant. 

Allen, F. H., Kennard, 0., and Taylor, R., Systematic analysis of structural data as a research technique in organic chemistry, Acc. Chem. Res., 16, 146-153 (1983). Vranka, R. G., and Amma, E. L., Metal ion-aromatic complexes. II. The crystal structure of the 1 1 silver nitrate-pyrazine complex, Inorg. Chem., 5, 1020-1025 (1966). Kubel, F, and Strahle, J., Crystal structure of polymeric bis(dismethyl-glyoximato)pyrazine iron (II), Z Naturforsch. B, 38, 258-259 (1983). 

Tetraazafulvalenes bearing two pyrazole subunits could be prepared by an original way. Tlius, treatment of benzylidene acetophenone with iso-pentylnitrite leads to an A, A -dihydroxy-bipyrazolyl-A, A -oxide, which in turn can be oxidized to TAF of type 100 (72CC961, 79JOC3211). Another type of oxidative dimerization was observed by the reaction of the electron-rich l-methyl-2,4-bis(dimethylamino)imidazole with silver salts (83TL3563). A bis-cation was isolated in 30% yield in the presence of sodium tetrafluo-roborate an unsymmetrical structure 101 was predicted from its NMR data (Scheme 40). 

Isoxazol-5-ones can exist in three different types of structures, cf. 45- 7 (R = H). Early investigators assigned structures to these compounds on the basis of unreliable chemical evidence thus the NH structure 47 was favored because the silver salt of 3-phenyl-isoxazol-5-one reacts with methyl iodide to give a product which was incorrectly (see reference 44) formulated as the iV-incthyl derivatives (cf. also reference 46). Bromine titration data led to assignment of an incorrect structure to 3,4-diphcnylisoxazol-5-one cf. article I (Volume 1), Section II,A. Comparison of the dipole moments of 3-phenyIisoxazol-5-one with those of the methyl derivatives 45 (R = Me) and 46... 

Calculate the atomic radius of each of the following elements from the data given (a) silver, fee structure, density 10.500 g-cm 3 (b) chromium, bcc structure, density 7.190 g-cm-3. 

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