Solid state studies

6H2O possesses either octahedral co-ordination consisting of four phosphate oxygens and two water molecules or tetrahedral co-ordination by four phosphate oxygens (Zn—O = 1.92-2.18 A).  

Polymeric zinc phosphinates of the stoicheiometry Zn(0PR20)2, which may be soluble or insoluble depending on the R group, have been prepared. The insoluble derivatives have structure (12), while either structure (13) or (14) may be true for the soluble polymers.  

Zinc halides react with the anions [P(CHC0CH2R)0(0Et)2] (R = NCH2CH2 OCH2CH2 or N(CH2)4CH2) to yield the complexes ZnLX (X = Cl, Br, or I) which 

Averbuch-Pouchot, A. Durif, and J. C. Guitel, Acta Cryst., 1975, B3I, 2453. 

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Conventional physical descriptions of materials in the solid state are concerned with solids in which properties are controlled or substantially influenced by the crystal lattice. When defects are treated in typical solid state studies, they are considered to modify and cause local perturbations to bonding controlled by lattice properties. In these cases, defect concentrations are typically low and usually characterized as either point, linear, or higher-order defects, which are seldom encountered together. 

By analogy with solid-state studies. Slater had the idea of writing the atomic Hartree-Fock eigenvalue equation... 

Dialkyl zinc compounds form phosphine complexes of formula RZnP(SiMe3)2 on addition of one equivalent of bis(trimethylsilyl)phosphine. Solution and solid-state studies showed that the complexes are dimeric or trimeric in solution or the solid state. Bis(trimethylsilyl)phosphido-methylzinc crystallizes as a trimeric molecule with a Zn3P3 core in the twist-boat conformation. Bis(trimethylsilyl)phosphido- -butylzinc, shows a similar central Zn3P3 fragment. The sterically more demanding trimethylsilylmethyl substituent forms a dimeric species of bis(trimethylsilyl) phosphido-trimethylsilylmethylzinc. Solution studies of bis(trimethylsilyl)phosphido- .vo-propyl-zinc demonstrate a temperature-dependent equilibrium of the dimeric and trimeric species and the crystalline state contains a 1 1 mixture of these two oligomers. A monomeric bis(trimethyl-silyl)phosphido-tris(trimethylsilyl)methylzinc has also been synthesized.313... 

The monochalcogenides 43 can also theoretically exist in more than one tautomeric form an N-H tautomer 43a, a P-H tautomer 43b or an E-H tautomer 43c. Solution and solid-state studies on these compounds show that, depending upon the nature of the R substituents, either the N-H or the P-H tautomer predominates. Substituents which lead to increased basicity of the phosphorus lone-pair (e.g., R = NMe279, Pr80) have been shown to favour the formation of the P H tautomer, whereas in systems where the phosphorus lone pair is less basic (e.g., R = Ph81) the N-H tautomers are favoured. 

This chapter will concentrate on the electronic spin-state crossover observed in the iron and cobalt complexes formed with the HB(pz)3 and HC(pz)3 ligands and their various methyl derivatives. In the majority of cases, the spin-state crossover occurs in the solid state and, as a consequence, solid state studies will be covered first, followed by the more limited studies... 

The data obtained from this 170 study on the Re(V), also that obtained in DMSO solutions, can be correlated with results from previous X-ray crystallographic and infrared solid-state studies on these oxocyanorhenate(V) complexes and are summarized in Fig. 12. 

Solid-State Studies Phase Transitions and Thermochromism 599... 

Solid-State Studies Phase Transitions and Thermochromism 3.11.5.3.1 Single crystal X-ray crystallography... 

Since the identification of bona-fide hydrogen bonds in solid state studies is often a controversial issue, in particular in the cases involving weak donors [10]... 

Many researchers refer to stems 1, 2, and 3 using their Roman numeral equivalents—that is, stems I, II, and III. These motifs are also denoted as helices I, II, and III. It should be noted at the beginning of this hammerhead ribozyme discussion that structure-function relationships, the role of various nucleobases, metal ion participation in catalysis, and other features of the system have not been completely delineated and in some cases remain controversial. Globally, the hammerhead fold appears to be similar in both solution and solid-state studies. In solution, however, the central core of the hammerhead construct appears to be highly dynamic. This may account for different experimental results among the analytical techniques used in solution and certainly explains some distinct differences seen between solution and solid-state (X-ray crystallographic) structures. 

SOLID-STATE STUDIES (CHEMICAL MECHANICAL POLISHING) 243... 

Table 1. Decay properties and availability of actinide isotopes for solid state studies ...

The preparation and properties of numerous actinide haUdes have been described by D. Brown Although the oxidation numbers of actinides in halides can vary from II to VI, most solid state studies are limited to di-, tri- and tetrahalides. 

Section 6.2, the crystal forces are of magnitude comparable to those inducing complex formation. Thus a complex in the solid state can have a different structure from that in solution. The complex of p-nitrophenol 74 with hexakis(2,6-di-OMe)-a-cyclodextrin 75 illustrates this point, exhibiting strikingly different modes of entrance of the guest into the host cavity in these two states (Figure 3.4) [39]. Nevertheless, numerous solid state studies ofthe complexes... 

C NMR studies, especially in the solid state (83H(20)1713), are of value in studies of tautomerism (83H(20)1713, 86ZC378). Solid state studies on imidazole (and pyrazole) show there are three distinct signals for the annular carbon atoms (imidazole C-2, 136.3 C-4, 126.8 C-5, 115.3 ppm). Proton exchange does not occur in the solid, hence the compounds resemble their crystal structures. Comparison with the corresponding chemical shifts for 1-methylimidazole (137.6, 129.3, 119.7 ppm) implies that the tautomerism has been frozen in the solid state (81CC1207). Solid-state examination of 2,2 -bis-lH-imidazole also reveals frozen tautomerism. 

Apart from structural factors annular tautomerism is strongly influenced by the aggregate state of the compound. Gas-phase and solid state studies of tautomerism have received much attention recently because of the development of methods such as X-ray crystallography, CPMAS NMR, microwave spectroscopy, etc. Low temperature H NMR is the simplest and most straightforward method to determine Kx it only requires that proton transfer be slow enough to observe separate signals for both tautomers, and that the equilibrium is not shifted too much towards one of the tautomers (about 5% of the minor tautomers seems the limit). More detailed information on tautomerism of key azole systems is given below. 

Reaction Cavities of Alkanophenones in Neat Solid and Liquid-Crystalline Phases. As mentioned previously, solid-state studies on the Norrish II processes of alkyl aryl ketones are unambiguous with respect to the triplet multiplicity of the reactive excited state. On the other hand, a bulky aryl auxochrome can create complications during the transformation of the excited triplet states to photoproducts in neat anisotropic phases. 

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