Structure of the Complex Ion in Aqueous Solutions of Zirconyl and Hafnyl Oxyhalides

Abstract

X-ray scattering by aqueous solutions of MOX2·8H2O (M=Zr and Hf, X=Cl and Br) can be explained if one assumes the existence of a complex [M4(OH)8 (H2O)16]X8. The metal atoms in this complex are arranged in a square and are held together by double OH bridges along each edge. In addition, each metal atom is bound to four additional water molecules in such a manner that the configuration about the metal is a square Archimedes antiprism. The halogen ions are not bound directly to the metal. They do, however occupy definite positions in the complex, and are presumably held in place by electrostatic forces. The structure is very similar to that which has been found in the crystalline oxyhalides.

Preparation of Delaminated Clay Having a Narrow Micropore Distribution in the Presence of Hydroxyaluminum Cations and Polyvinyl Alcohol

“…Usually, the resultant pillared clay has a basal spacing of 18-20/~, yielding interlayer space having pore openings of ~ 9 ,~. The polyoxymetal cations apparently aggregate to form cationic oligomers in solution (Johansson, 1960;Muha and Vaughan, 1960). The size of these oligomers appears to control the size of the pore openings in the pillared clays.…”

Detection of Polynuclear Zirconium Hydroxide Species in Aqueous Solution by Desktop ESI-MS

“…9) There may be some similarities and differences in these values in Table 1. As a cause of slightly high values of log i;q compared with Walther et al's data, the polymerization to larger species might proceed due to the longer aging period compared with Walther et al's samples aged for at least 1 h. For comparison of the values, however, it is noted that the present log i;q values are obtained by assuming such predominant species as (1,1), (2,4), (3,6), (4,10), (5,12), (8,22), (10,30), and (12,38) in the pH c range of 0.05 to 2.10 in the present study. Because of this assumption, the values are considered to be only temporal, for which further confirmation is needed.…”

“…In the case of Zr, only mononuclear species were considered in some early studies of hydrolysis constants, 1,2) but the formation of polynuclear and colloidal species was observed in many studies. [3][4][5][6] For instance, measuring the size distributions of such species by ultrafiltration (at 3 kDa), Sasaki et al proposed that mononuclear, polynuclear, and colloidal species coexist in weakly acidic and neutral pH solutions. 7) On the other hand, Cho et al developed a method by combining laserinduced breakdown detection (LIBD) with slow coulometric titration in order to sensitively detect the formation of tiny zirconium colloids (>5 nm in size) without the ultrafiltration process.…”

Oxo‐Anion Modified Oxides

“…Zirconium salt solutions have a number of industrial uses [59,60] and their chemistry has been studied extensively [61][62][63][64][65][66][67][68][69][70][71][72][73]. In general, zirconium(IV) cations have a strong tendency to hydrolyze in aqueous medium, i.e.…”

“…8+ is present; it can be neutralized through attachment of eight chloride ions [62,63]. The tetrameric complex has been found in zirconium oxychloride solutions [64,68,71], in zirconium perchlorate solutions [66] and in zirconium nitrate solutions [65].…”