Chromium , crystal structure

The chromium crystal structure is characterized by a cubic lattice with valence 6 and coordination number 8. Therefore, each chromium surface atom is able to attach k <3 carbonyl CO groups without destruction of the lattice (Darken Gurry, 1960 Atkins,... 

Stainless and heat-resisting steels containing at least 18% by weight chromium and 8% nickel are in widespread use in industry. The structure of these steels is changed from magnetic body centered cubic or ferritic crystal structure to a nonmagnetic, face-centered cubic or austenitic crystal structure. 

Now in the case of chromium carbide separation from the steel, three possible crystal structures may be taken up, those of CrjC, (or CrjsCJ, Cr7C3 and CrjCj. It is necessary first to calculate the free energies of formation of the compounds from pure chromium and carbon. The results are ... 

Chromium, (ri6-benzene)tricarbonyl-stereochemistry nomenclature, 1,131 Chromium complexes, 3,699-948 acetylacetone complex formation, 2,386 exchange reactions, 2,380 amidines, 2,276 bridging ligands, 2,198 chelating ligands, 2,203 anionic oxo halides, 3,944 applications, 6,1014 azo dyes, 6,41 biological effects, 3,947 carbamic acid, 2,450 paddlewheel structure, 2, 451 carboxylic acids, 2,438 trinuclear, 2, 441 carcinogenicity, 3, 947 corroles, 2, 874 crystal structures, 3, 702 cyanides, 3, 703 1,4-diaza-1,3-butadiene, 2,209 1,3-diketones... 

The structures of these stannylene complexes closely resemble those of carbene complexes. In Fig. 12 the crystal structure of the stannylene complex 4 is displayed the tin atom, the two carbon and the chromium atoms are equi-planar 30). 

A colorless mineral known as corundum (composed of aluminum oxide) is colorless. A red variety of corundum known as ruby, a precious stone, owes its color to impurities of chromium within the crystal structure of corundum. Blue and violet varieties of corundum are classified as sapphires, the blue being the result of iron and titanium impurities, and the violet of vanadium impurities within the corundum crystal structure. Another colorless mineral is beryl (composed of beryllium aluminum silicate) but blue aquamarine, green emerald, and pink morganite, are precious varieties of beryl including different impurities aquamarine includes iron, emerald chromium and vanadium, and morganite manganese. 

Eujii T, Suzuki D, Gunjii K, Watanabe K, Moriyama H, Nishizawa K (2002) Nuclear field shift effect in the isotope exchange reaction of chromium(III) using a crown ether. J Phys Chem A 106 6911-6914 Gale JD (2001) Simulating the crystal structures and properties of ionic materials from interatomic potentials. Rev Mineral Geochem 42 37-62... 

The crystal structures of (3a,4-8,8a-f/)-[5.7,8-trimethyl-8H-cyclohepta-(fe)-thiophen]- and (1—3,3a.8a-f7)-[5,7-dimethyl-4//-cyclohepta-(c)-thiophen]-chromium tricarbonyl complexes, (55) and (56). respectively, have been determined. ... 

The crystal structure of tricarbonyl-(2,4,6-triphenylphosphorin)chromium (57) has been reported. The Cr(CO)3 group has a central position above the... 

The crystal structure of the chromium metallocarborane salt Cs[Cr(BgC2-H9Me2)2] has been determined. The anion consists of two icosahedra sharing a chromium atom as a common vertex. ... 

CrP has been synthesized by reaction of the elements at pressures of 15— 65 kbar. The crystal structure involves chromium atoms co-ordinated by six phosphorus atoms in a distorted octahedral arrangement with Cr—P = 232—239 pm. CrMAs (where M = Co or Ni) have been characterized by A"-ray diffraction spectra. ... 

M. Krumpolc, B. G. DeBoer, and J. Rocek, A stable chromium(V) compound. Synthesis, properties and crystal structure of potassium bis(2-hydroxy-2-methylbutyrato)-oxochromate(V) monohydrate, J. Am. Chem. Soc., 100 (1978) 145-153. 

Since little is known about crystal structures of the low-temperature mked oxides of niobia, it is difficult to explain from a theoretical point of view the good results obtained for doping with vanadium or chromium. It appears that the vanadium and chromium are present in the catalyst in a unique environment, which makes... 

The intermediate cyclooctene complex appears to be more reactive with respect to CS coordination and more sensitive to oxidation when the arene ring bears electron-withdrawing groups (e.g., C02CH3). Dicarbonyl(methyl rj6-benzoate)-thiocarbonyl)chromium is air stable in the solid state and reasonably stable in solution.9 The infrared spectrum exhibits metal carbonyl absorptions at 1980 and 1935 cm"1 and a metal thiocarbonyl stretch at 1215 cm"1 (Nujol) (these occur at 1978, 1932, and 1912 cm"1 in CH2C12 solution).10 Irradiation of the compound in the presence of phosphite or phosphine leads to slow substitution of CO by these ligands, whereas the CS ligand remains inert to substitution. The crystal structure has been published."... 

Wood, R. M., Aboud, K. A., Palenik, R. C., and Palenik, G. J. (2000). Bond valence sums in coordination chemistry. Calculation of the oxidation state of chromium complexes containing only Cr-O bonds and a redetermination of the crystal structure of potassium tetra(peroxo)chromate(V). Inorg. Chem. 

The crystal structure determination by Vahrenkamp and Noth proves the assumed structure of this new and interesting chromium-tricarbonyl complex 56 (Fig. 16). 

Chromium atoms provide a unique route to 7r-pyridine complexes. No simple product has been isolated from the reaction of pyridine and chromium atoms, but 2,6-dimethylpyridine and chromium atoms give a low yield of (i 8-2,6-dimethylpyridine)2chromium characterized by a crystal structure showing essentially planar pyridine rings (103). A mixture of pyridine with either PF3 or mesitylene gives a 7r-C5H5N complex ... 

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