Refinement of the crystal structures of (C6H5)4AsI3 and CsI3 at 20°C and at –160°C

Tetraphenylarsonium trichloride

“…A small deviation from symmetry would be very difficult to detect by X-ray diffraction (Rae, 1975), as neither any extra reflexions nor any change in Laue symmetry would be observed. This is also true for the isomorphous crystal structures [As(C6Hs)4]I 3 (Runsink, Swen-Walstra & Migchelsen, 1972), [P(C6Hs)4]Br2I I (M/iller, 1979) and [P(C6Hs)4]Br3 (Bogaard & Rae, 1981). In contrast, the symmetric form of [N(C2Hs)4]I a has space group Cmca, and asymmetry of the I~-ion would cause the destruction of the symmetry element 2 parallel to a.…”

“…The crystal structures of compounds involving trihalide ions are of interest in that whenever site symmetry allows an asymmetry of the trihalide ion, statistically meaningful asymmetry is observed (Runsink, Swen-Walstra & Migchelsen, 1972). For some compounds, e.g.…”

Crystal chemistry of tetraradial species. Part 2. Crystal structures of Et4NI, Ph4PBr•H2O, and Ph4PBr•2H2O

“…The volume-averaged symmetry simulated at an N site can be as high as C4h, D2d, and D4h, and the alternative orientations need not be populated equally (cf. (32) mXC(X = C1, Br, I. C1O4, MnO4) eSbBr6 (15)" bAuBr; (1 8) ppBr3 (20) paBr3(Il) (2 1) P P I B~~ (23) pal3 (25) ppSnX3 (X = C1, Br) (27) paAuCI4 (30) "ZB, zincblende, W, wurzite; m, Me4N; ma, Me4As; ms, Me4Sb; e, Et,N; p, t i -Pr,N; b, ti-Bu4N; pp, Ph4P; pa, Ph4As; pb, Ph4Bi. Distortions from the aristotype symmetry are not detailed here.…”

Ring cleavage of imidazole to oxamide by reaction with dioxygen in the presence of a CuI–amine complex. Structure of μ-oxamidato-bis[(1,4,7-trimethyl-1,4,7-triazacyclononane)copper(II)] triiodide iodide

“…As the shortest non-bonding I...I contacts are 5.080 ,~ and as hydrogen-iodine interactions (> 3.2 ,~) are of negligible influence, the If groups may be regarded as isolated anions. Nevertheless, the group is asymmetric with two I--I distances [2.895 (3) and 2.942 (3) ]k] different from the value of 2.920 A for a 'free' triiodide anion (Runsink, Swen-Walstra & Migchelsen, 1972). However, the large anisotropic displacement parameters indicate that the atomic positions of the triiodide suffer from disorder and so the derived bonding parameters are less meaningful.…”