The Crystal Structure of Antimony Pentachloride at -30°

Abstract

The 489' transformation in Na2C03 makes its first appearance at 67.5 mole yo. No level range is observed indicating that this transformation is not quite as spontaneous as its opposite member. The 361' transition in NaZC03 is not detectable until approximately 92.5 mole yo from which point its latent heat increases continuously. The X-ray data indicate that the upper and lower curves have approximately a 10 mole yo separation a t room temperature which explains the rapid decrease in the magnitude of the spontaneous latent heat. The consistency of the patterns in the 8-E two phase region indicates that the X-ray sample preparation resulted in a fairly good approach to equilibrium and this also lends support to the validity of the entire diagram as constructed.NOTE ADDED IN PRooF.-The author has hitherto been unable to offer any explanation for the heat effects a t ca. 620" reported in ref. 2. Subsequent to the compilation of this manuscript, a probable explanation for the "anomalous heat effects" was forthcoming in a private communication from Drs. which is abstracted herewith. I n the course of differential thermal analysis studies in the sodium carbonate-silica system we also have been unable to observe this peak (at ca. 600") when using analytical reagent sodium carbonate However, when using commercial sodium carbonate, which is known to contain up to 0.5% sodium chloride, a small peak a t about 620" is observed. D. T. A. curves of sodium carbonate-sodium chloride mixtures (both of analytical reagent quality) show a small peak a t about 620' which increases in area with increasing chloride content. Moreover Mellor' states that eutectic melting occurs between sodium carbonate-sodium chloride mixtures a t 636". Analytical reagent quality potassium carbonate shows no peak a t about 620", but a peak appears when analytical reagent quality potassium chloride is added as an impurity Mellor again gives the eutectic melting temperature of these two substances a t 636".

Solid State Structures of AsCl5 and SbCl5

“…The high temperature form is the one previously analyzed by X-ray crystallography, the hexagonal phase [6]. The results of our remeasurement are in full agreement with the older work.…”

“…The similarity of the molecular and solid state structure came as a surprise, since PCl 5 as a molecule has a trigonal bipyramidal structure [3], but in the solid state it crystallizes as [(PCl 4 ϩ )(PCl 6 Ϫ )] [4]. SbCl 5 , also trigonal bipyramidal as a molecule [5], has the same structure in the solid state, according to an early x-ray analysis [6]. But changes in the vibrational, n.q.r, and Sb-Mößbauer spectra at low temperatures have already previously been interpreted as a dimerisation into [Cl 4 SbCl 2 SbCl 4 ], namely a double chlorine bridged (two edge sharing octahedral) structure like in Nb 2 Cl 10 [7,12].…”

“…Results of ab initio calculations on AsCl 5 , SbCl 5 , As 2 Cl 10 , and Sb 2 Cl 10 : geometries, vibrational frequencies, energies.In search for reliable preparation and recrystallisation conditions for AsCl 5 we accidentally observed salts of the AsCl6 Ϫ anion. This anion is known[17], and there exists a single crystal structure determination of [(C 6 H 5 ) 4 P ϩ AsCl6 Ϫ ][18].…”

“…This anion is known[17], and there exists a single crystal structure determination of [(C 6 H 5 ) 4 P ϩ AsCl6 Ϫ ][18]. In case the solution AsCl 3 /Cl 2 contains H 2 O, (and with this HCl), two compounds [(H 5 O 2…”

The preparation and characterisation of Sb3Cl11F4

“…From a stereochemical point of view they are of interest, since the antimony atom rarely remains five coordinate. Indeed only for SbCl, has fivecoordination been established (2). However, a phase change is thought to occur at low temperatures, resulting in a different structure.…”