Crystallographically distinct

This compound has two crystallographically distinct vanadium sites. While the static spectrum is a superposition of two powder patterns of the kind shown in Figure 3, MAS leads to well-resolved sharp resonances. Weak peaks denoted by asterisks are spinning sidebands due to the quadrupolar interaction. 

In addition to the surface physics and chemistry phenomena involved, a further effect may follow the interaction at the hydrogen-metal surface, that is the absorption of hydrogen by the bulk phase of the metal. This absorption leads to the formation of a solid solution within a certain, usually low, range of hydrogen concentrations. However, with several transition metals, exceeding a certain limit of hydrogen concentration results in the formation of a specific crystallographically distinct phase of the... 

A novel cadmate complex has been formed by the reaction of Cd(NH2>2 with I C=CH in the presence of acetylene in liquid ammonia.250 The potassium salt, K2Gd(CCH)4-2NH3 191, has been structurally characterized. The cadmium center is tetrahedrally coordinated to four acetylide units with which it forms Cd-C bonds of 2.23-2.25 A (Figure 29). The acetylide ligands are 7r-coordinated to two crystallographically distinct potassium ions whose coordination sphere is completed by two ammonia molecules. 

The shape selectivity of zeolites is influenced by the location and distribution of charge-compensating cations. The charge-compensating ions other than protons are all quadrupolar. and Li NMR spectra of dehydrated LiX-1.0 identified three crystallographically distinct sites [221]. In the case NaX with Si/Al ratio of 1.23, six distinct sodium sites were identified using fast Na NMR, DOR and nutation techniques [222]. Na MQMAS has been extensively studied for zeolites X and Y [155]. Other cations like Cs and La in zeolites have also been investigated [155,... 

Both the V and Li NMR spectra show multiple vanadium and lithium local environments for the as-synthesized material x = 0.15), and the spectra cannot be explained by using a simple model based on the number of crystallographically distinct vanadium sites. On Li-ion intercalation, the V resonances sharpen and shift to higher frequencies (Figure 15) three sharp resonances along with two broader resonances are clearly resolved for the samples prepared at potentials of 3.4 and 3.0 V (x = 0.3 and 0.5, respectively). This behavior is consistent with solid—solution behavior in this potential range and is ascribed to the presence of localized defects at X close to 0 and electron delocalization for 1 > x > 0.05. Three lithium sites were observed in the Li... 

An example of this is the gold-thallium complex n[Au(CN)2] [69], prepared by reaction of T1N03 and K[Au(CN)2]-2H20 in the 90s by Patterson et al. This group carried out a pioneering study of the luminescence properties of this complex and their theoretical interpretation. The structure showed a complexity that made the analyses difficult. Thus, neutron diffraction studies showed thallium-gold interactions of 3.446 and 3.463 A, shorter than the sum of their van der Waals radii (3.62 A) in one of the three crystallographically-distinct Au sites in the crystal. 

Between classes a and / there has been found a true crystallographic distinction as will be noted on consideration of the space groups listed in Table 1. The non-phototropic anils occur in lattices which are centro-symmetric, whereas the lattices of the phototropic anils have no centre of symmetry. 

The structure of Cd2(pn)2(NCS)4 is polymeric, containing bridging NCS groups. Two crystallographically distinct Cd atoms are again present one is octahedrally coordinated by five N atoms (two from propylenediamine and three from SCN) and one S atom, the other by three N and three S atoms.1068... 

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