Types of cationic complexes based on oxocentred tetrahedra [OM₄] in the crystal structures of inorganic compounds

Abstract

The renormalization prescription of t'Hooft and Veltman is used to construct crossover scaling functions for the susceptibility and free energy in an isotropic n vector model. Some dilliculties in interpreting the E expansion in this context are discussed, and the formalism is illustrated by a calculation of the expansion factor a ' of a polymer in dilute solution.

Yeomanite, Pb2O(OH)Cl, a new chain-structured Pb oxychloride from Merehead Quarry, Somerset, England

“…From the viewpoint of bond valence theory, these bonds are the strongest in the structure and thus it makes sense to consider the O 2-anions as coordination centres for the oxo-centered OPb 4 tetrahedra. The mean O-Pb length in the O1Pb 4 tetrahedron is 2.31 Å which is typical for such units (Krivovichev et al, 1998 (Figure 6b; Cooper and Hawthorne, 1999), However, the hydroxyl groups in that mineral are arranged in a very different way and do not result in the subsequent formation of OHPb 3 triangles. Similarly, the structures of penfieldite, Pb 2 (OH)Cl 3 (Merlino et al, 1995) and laurionite, Pb(OH)Cl (Venetopoulos and Rentzeperis, 1975) It is also of interest that yeomanite is not structurally related to damaraite, Pb 3 O 2 (OH)Cl (Keller et al, 2001) 2+ chains in damaraite are the main building units in the growing number of "Mendipite Group" minerals mendipite, damaraite, chloroxiphite, and rickturnerite.…”

Crystal Chemistry of Lead Oxide Hydroxide Nitrates I. The Crystal Structure of [Pb6O4](OH)(NO3)(CO3)

“…(OPb ) tetrahedra may polymerize by sharing edges and vertices to form polyions of di!erent connectivity and dimensionality (7}11). The types of oxocentered tetrahedral units were reviewed in (12,13) and some details concerning their relationships to other structural elements may be found in (14). The nature of chemical bonds in (OPb ) tetrahedra and related lead oxo/hydroxo moieties were studied by Bengtsson and Ho!mann (15) who remarked upon the existence of closed-shell Pb2Pb interactions in such units.…”

Crystal structure and magnetic properties of NaCuII[(CuII3O)(PO4)2Cl]

“…For the crystal-chemical classification the structure description by oxygen-centered metal tetrahedra seems to be beneficial especially in the case of copper(II), where the definition of a coordination polyhedron is sometimes difficult because no clear gap in the distances distribution is observed. Using this approach, the structural similarity to sulfate minerals becomes apparent [25,29]. For kamchatkite [30] [31], similar 1 1 fOCu 3 g chains ( Fig.…”

“…Each of these common vertices is in addition part of two edge-sharing [CuO 4 Cl] polyhedra. Focusing on the special coordination of O3 (Table 3) leads to a structure description in terms of oxygen-centered polyhedra OM 4 (M ¼metal) [25]. This approach simplifies the chain representation as shown in Fig.…”

“…The tetrahedra chain is reminiscent of chain silicates for which a comprehensive nomenclature was developed [26]. Applying this to the observed linkage, the chain belongs to the group of unbranched zweier single chains with the formula fuB,1 1 1 g½O 2 Cu 6 [25]. The overall crystal structure is shown in Fig.…”