Crystals of complexes

Crystals of complex 112 suitable for an X-ray structure determination were obtained on cooling a solution in pentane to — 30 °C. The structure determined is shown in Fig. 7.9. The most remarkable structural feature of 112 is that the gallium center is connected to the zirconium through two different c-carboxylic bridges. One of them contains the cyclo-C6Hg system, which is t]1-bonded to gallium and r 2-coordinated to zirconium. It is noteworthy that carbon atom C-2 is planar tetracoordinate. It is connected to four neighboring atoms in the c-plane, specifically to carbon atoms C-l and C-3 and to both metal centers [175]. 

The vibrational spectra of inorganic molecular crystals of binary compounds of the type AB and AB2, as well as ionic crystals of complex anions and cations, have been studied recently under pressures up to 70 Kbar (217—219). By this technique it is possible to differentiate between internal and lattice vibrations (220) since lattice modes have a greater dependence on pressure. 

Complexes A and B can be simply prepared by passing HI into a solution of TPO in acetic acid at room temperature. Crystals of complex A form immediately and can be isolated by filtration. The suggested composition of complex A follows from NMR and elemental analysis. On standing of the filtrate (in air) further crystals of composition B are formed. Similar complexes were isolated with pyridine N-oxide. 

Compounds can be prepared either in polycrystalline form, often referred to as ceramics, or as single crystals. The synthesis of oxides in polycrystalline form is typically straightforward relative to single crystal growth. For the growth of single crystals of complex oxides, a unique growth system appropriate to the chemistry and... 

In the more complex structures it is usually necessary to determine a number of parameters simultaneously in crystals of complex organic compounds, for instance, more often than not the atoms are all in general positions and there are therefore three parameters for each atom. Such problems cannot be solved by the methods described for isolated parameters. It is necessary to postulate likely positions for the atoms, to calculate the intensities which these positions would give, and to compare these calculated intensities "with those observed. The prospects of... 

In the crystal of complex 1 3, hydroquinone and hydrazine molecules form an extensive H-bonding network in which all oxygen and nitrogen atoms are fully coordinated in a super-tetrahedral architecture. In this aggregate, the amino and... 

Fig. 10. Confocal microscope emission spectra of a single crystal of complex 1 before (black spectrum) and after (red spectrum) insertion of anthraquinone molecules inside the pores. As can be seen by eyes the emission of the crystal change from orange to green. Reproduced with the permission of Wiley-VCH (170).

Fig. 3.10. Topography of Complex III. Complex III is a dimer in the two-dimensional crystal form studied by electron microscopy. The shape of the membrane-bound enzyme particle was resolved by image reconstruction of micrographs [230]. The location of various components was predicted by comparing crystals of Complex III with those of a subcomplex lacking the Rieske FeS protein and the core proteins [222,231]. The schematic figure is adapted from Li et al. [222].

Crystallization of complex halides from solution containing crown ethers results not in the complexation of the actinide by the ether oxygen atoms, but rather in the isolation of [AnXg] " salts in which the crown appears to act as a crystallization aid. " ... 

We show below how these inaccuracies in the Lorenz-Lorentz formula can be eliminated. We employ the local field method to modify this formula and apply it to anisotropic organic crystals of complex structure. We discuss below also a variety of their optical properties which were earlier analyzed in a less general form only in the framework of exciton theory. We explain how it has... 

Hydration isomers. Hydration isomers exist for crystals of complexes containing water molecules, for example CrCl3z6H20. This compound can exist in three different crystalline forms, in which the number of water molecules directly attached to the Cr ion differs. 

P-2 Small crystals of complex 88, inadequate for single-crystal XRD analysis, were analyzed with synchrotron radiation in the 0.024-0.065 nm range, using Laue s method for recording diffraction data. The complex consists of an AuOss cluster with Au bonded to a PPhs ligand and the Os atoms to the other ligands, including a cr bond to C—O . 

Li Z, Nian H, Feng T, Jiang D (2014) Sohd-state grain growth of garnet single crystals of complex composition. Ceram Int 40 10193-10196... 

This would agree with the observation that often prior to crystallization of complex (inorganic or organic) systems, precursor species are formed of the order of a few nanometers. Interesting in this context is the example of zeolite crystallization that we described in... 

Experimental verification of the CMD mechanism was pubUshed in 2012 by Ozawa and coworkers, who isolated a single crystal of complex 42 suitable for X-ray analysis and studied the catalytic activity towards C H activation. In solution, this dimeric species disproportionates into two molecules of 43, which is the active catalytic species. They used this species under catalytic conditions to compare the rates of C-H activation of 2-methylthiophene in a competition experiment with half an equivalent of bromobenzene and 2-bromo-l,3-dime-thylbenzene (Scheme 19.7). Oxidative addition, not C H activation, was determined to be the rate-limiting step since coupling with bromobenzene took place preferentially. ... 

Examples of seeding have been recently reported for the preparation of single crystals of complexes of gabapentin and ZaCh and CuCh" or complexes with 4-aminosalicylic acid and piracetam, which had been obtained by mechanical reaction." ... 

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