Interatomic Distance Predictions for Computer Simulation of Crystal Structures

The composition and structure of jeanbandyite and natanite

“…In dusssertite, the As atom forms a highly regular AS04 tetrahedron (Fil;':' 3) and the average As-O bond length, 1.684(3) A, is almost identical to the values reported for the average arsenate tetrahedron in arsenates (1.683 A, Shannon and Calvo, 1973;1.682 A, Baur;1981). ]1' Ass-had been replaccd by the much largcr Sb5-, then an apprcciably increased bond length would have been observed, probably accompanied by a distortion of the tetrahcdron.…”

BaMgAs2O7 and BaCoAs2O7 – synthesis, crystal structures and twinning of two new barium diarsenates

“…As expected, the Mg/Co [5] -O bonds are slightly shorter than the average Mg/Co [6] -O bond distances. Baur [26] gives an average Mg [6] -O distance of 2.085 Å; according to Wildner [27] the overall mean Co [6] -O bond lengths for 112 CoO 6 octahedra is 2.1115(621) Å. The bond-length distortions were calculated in analogy to that defined for octahedra [28,29] according to the formula ∆ tetr-…”

The crystal structures of kidwellite and ‘laubmannite’, two complex fibrous iron phosphates

“…The average Fe(2)ÀO distance, 2.072 Å (Table 9), also provides evidence that Fe(2) is occupied by a mixture of ferrous and ferric iron in an approximate ratio of 1:1. According to Baur (1981) The relatively short Fe(1)ÀFe(2) distance in the face-sharing dimer, 2.924(1) Å , makes it understandable that only this dimer accepts Fe 2+ , but not the other, edge-and corner-sharing dimers: if it would host only Fe 3+ cations, electrostatic cation repulsion across the shared face would be much stronger and could lead to severe intrapolyhedral strain. In kidwellite, which contains only Fe 3+ ions in an otherwise very similar face-sharing dimer, the Fe(1)ÀFe(2) distance is considerably longer, 2.967(2) Å , as would be expected from a stronger repulsion across the shared face.…”