Bond-strength-bond-length relationships for bonds between oxygen and H+, Li+, Be2+, B3+, Na+, Mg2+, Al3+, Si4+, P5+, S6+, K+, Ca2+, Sc3+, Ti4+, V5+, Cr6+, Mn2+, Fe3+, Fe2+, Co2+, Cu2+, Zn2+, Ga3+, Ge4+ As5+ have been derived by requiring that the sums of bond strengths around cations be equal to their valence in 417 crystals whose structures accurately determined. The relationship is form s = (R/R0)-N where strength, R length R0 N are fitted constants. It further shown all ions with an...

The structures observed for many inorganic solids are the result of a compromise between conflicting requirements chemical bonding and threedimensional geometry. ideal structure bond geometry can be predicted using bondvalence model which is developed in some detail. constraints imposed on this when mapped into three-dimensional space require, cases, that lengths strained. Particularly compounds containing bonds intermediate strength (e.g. oxides halides di- trivalent cations), relaxation...

ADVERTISEMENT RETURN TO ISSUEPREVArticleNEXTThe inorganic crystal structure data baseG. Bergerhoff, R. Hundt, Sievers, and I. D. BrownCite this: J. Chem. Inf. Comput. Sci. 1983, 23, 2, 66–69Publication Date (Print):May 1, 1983Publication History Published online1 May 2002Published inissue 1 1983https://doi.org/10.1021/ci00038a003RIGHTS & PERMISSIONSArticle Views1440Altmetric-Citations397LEARN ABOUT THESE METRICSArticle Views are the COUNTER-compliant sum of full text article downloads since...

The specification of a new standard Crystallographic Information File (CIF) is described. Its development based on the Self-Defining Text Archive and Retrieval (STAR) procedure [Hall (1991). J. Chem. Inf. Comput. Sci. 31, 326-333]. CIF general, flexible easily extensible free-format archive file; it human machine readable can be edited by simple text editor. designed for electronic transmission crystallographic data between individual laboratories, journals databases: has been adopted...

The asymmetry of hydrogen bonds arises from the repulsion between O atoms forming bonds. A bond-valence analysis leads to conclusion that strong and weak are different in kind, stronger ones (O-O less than 2.7 Å) involve strain linear while weaker greater have an extra degree freedom generally bent. strength bond is determined by a number factors such as requirement valences around each atom add up atomic valence, tendency for O-O distance be close Å, crystal-packing considerations which...

The DOS program VALENCE is designed to calculate bond valences from lengths and vice versa. It can also bond-valence sums average lengths, determine parameters the bonding environments of different cations.

Over 14 000 coordination environments of 100 different cations retrieved from the Inorganic Crystal Structure Database have been analyzed. For comparison predicted numbers (PCN's) calculated using ionic radius ratios. The observed are generally smaller than or equal to PCN's and their range, for most cations, can be a knowledge Lewis-base strengths available anions requirement that these close Lewis-acid strength cation. occurrence is associated with strongly directed bonds (electronic...

The deformation electron-density (dynamic Fourier) maps and the anharmonicity of atomic displacements in strontium titanate, SrTiO 3 (Gram-Charlier model), were studied by high-precision single-crystal X-ray diffraction analysis at 145(1) 296(2) K. Space group Pm3m, cubic, λ(Mo Kα) = 0.71069 A, Z 1, F(000) 84, T 145 (1)K, a 3.8996(5)A, V 59.30(2)A , D x 5.138(2) g cm -3 μ 26.778 mm -1 R 0.0063, wR 0.0040, S 1.05 for 131 unique reflections 296(2)K, 3.901(1)A, 59.36(5)A 5.133(4) 26.700 0.0071,...

The compound Hg 2.86 AsF 6 belongs to the tetragonal space group I4 1 /amd with lattice parameters a = 7.538(4) Å, c 12.339(5) and Z 4. structure was refined using 109 symmetry independent reflections by full matrix least-squares refinement final R value of 0.079. may be described as consisting octahedral − ions arranged on which contains linear, non-intersecting channels in two mutually perpendicular directions. Within these are infinite chains mercury atoms, each formal charge +0.35,...

Crystals of K 2 TeBr 6 are monoclinic, space group [Formula: see text] with a = 7.521, b 7.574, and c 10.730 Å; β 89° 40′. Atomic positions have been found by three dimensional X-ray diffraction analysis (least squares R 0.12). The crystals possess PtCl structure which is distorted to allow more efficient packing the comparatively large anions than possible undistorted cubic form. stereochemistry octahedral − ion (Te—Br 2.71 Å) discussed.

The crystal structure of triclinic potassium dichromate has been determined by single X-ray diffraction. cell constants are a = 13.367, b 7.376, c 7.445 Å, α 90.75°, β 96.21°, γ 97.96° with four K 2 Cr O 7 units per cell. Refinement 2600 reflections in both the space groups P1 and [Formula: see text] leads to same structure. This is agreement results anomalous dispersion measurements, confirming that correct group. final index, R, 0.054. two crystallographically independent ions similar,...

Abstract The large bond valence sums found for O 2– en-capsulated by Pb 2+ ions are shown to result from the use of inappropriate parameters. New values r o = 1.963 Å and b 0.49 recommended -O bonds.