Bromine NQR and Crystal Structures of Tetraanilinium Decabromotricadmate and 4-Methylpyridinium Tribromocadmate

Abstract

The(4-(CHThe relations between Br-NQR and crystal structures are discussed.

Crystal Structures of Piperazinium Tetrahalogenometallates (II) [C4H12N2]MX4 (M = Zn, Hg; X = Br, I)

“…In contrast to the above mentioned general trend, piperazinium tetraiodocadmate (II) was found to adopt an isolated anion structure in our previous work [13]. Furthermore, we found that a series of salts [C 4 H 12 N 2 ]MX 4 (II) (M = Zn, Cd, Hg; X = Br, I) show a single firstorder structural phase transition around 560 K [16]. Crystals of all these complexes seem stable, with decomposition temperatures above 600 K without any phase transitions between ca.…”

“…The structures of [C 4 (4) were determined using a Stoe IPDS instrument. From measured intensities corrected for Lorentz-polarization and absorption effects, the structures were solved by the direct techniques and Fourier syntheses, and refined by least-squares methods with programs given in ref [20].…”

“…A variety of polymeric structures of anions in the Cd compounds were detected, whereas only isolated tetrahedral ZnX 4 2− anions exist in the Zn compounds. In contrast to the above mentioned general trend, piperazinium tetraiodocadmate (II) was found to adopt an isolated anion structure in our previous work [13].…”

“…130 K and ca. 560 K. In order to elucidate this rather unusual lattice stability and the mechanism of the transitions at high temperatures, we determined the structures of [C 4 H 12 N 2 ]MX 4 (M = Zn, Hg; X = Br, I).…”

Tetraguanidium Hexabromocadmate, [C(NH2)3]4[CdBr6]. Crystal Structure and Bromine Nuclear Quadrupole Resonance

“…A nother quite stable and com m on com position is A2 CdBr4 with m ore or less distorted tetra hedral anions [C d B rJ20. Recently we have investi gated a num ber of brom ocadm ate complexes by X-ray diffraction and brom ine nuclear quadrupole resonance, N QR, and found several rather unusual types of polymer anions [1][2][3]. Besides the form ation of polymer anions, Cd1 1 may exist in the solid state with Br ligands as isolated octahedral anion [CdBr6]40 and we have studied the bromine (79'81Br) NQR in some complexes A4 [CdBr6] [4], The crystal structures of these complexes are of high symmetry and if A is a simple cation such as an alkali m etal ion, the octahedron [CdBr6] deviates only little from regu larity.…”