Crystal structure analysis incorrect

On a specimen which also originated from the Cu-Ni sulphide deposit Noril sk, Siberia, Russia, Fleet carried out a definitive crystal structure analysis of godlevskite. Discrepancies between the unit-cell parameters of [69KUL/ERS] and [87FLE] are attributable to incorrectly indexed powder data. 

The structure proposed earlier for catharinine (vinamidine) has now been shown to be incorrect catharinine is, in fact, a product of the fission of ring D in leurosine or vinblastine, but in a different sense from that postulated earlier. The structure of catharinine (247) was established by the X-ray crystal structure analysis of the non-vindoline component (248), obtained by the reductive cleavage of catharinine in acid solution. A plausible biogenetic derivation of catharinine from leurosine (249) is illustrated in Scheme 41. 

The first major obstacle that had to be overcome was twinning the tendency of a crystal to grow identical twin components, symmetrically united, as you see in the scanning electron micrograph in Figure 3. Twinning camouflages the crystal s true symmetry, and this can lead to incorrect structural analysis. 

Furthermore, we have shown that oxidation in air can also be used to control the average crystal size in ND powders with subnanometer accuracy. Three different characterization techniques were used for measuring the crystal size because such analysis is very complex for nanocrystals. While HRTEM is able to visualize ND crystals, the calculated size distributions are statistically not reliable and the average size is often overestimated. Agglomeration and difficulties in sample preparation do not allow accurate estimates on average crystal size values. XRD, which directly probes the crystalline structure of a material, is more reliable in terms of statistics and average values, but lattice distortion and strain can interfere with size effects in XRD pattern and lead to an incorrect interpretation of the results. 

Dibenzylidene-l, 3-ditelluretane was prepared by reacting tellurium with sodium phenylacetylide and acidifying the resulting mixture, which contains sodium phenylethyne-tellurolate, with hydrogen chloride in diethyl ether The structure of the compound was confirmed by single crystal X-ray analysis . The earlier reported formulation of this compound as 2-benzylidene-4-phenyl-l,3-ditelluracyclopent-4-ene is incorrect. ... 

The first preparation of a benziodazole heterocyclic system was reported by Wolf and Steinberg in 1965 [236]. The authors of this paper isolated the product of peracetic oxidation of 2-iodobenzatnide (163) and, based on the IR spectroscopy, incorrectly assigned the structure of 77-acetyl-l-hydroxy-3-(l//)-l,2-benziodazole-3-one 165 to this product. Structure 165 was also adopted in several other studies [259,328,329]. More recently, the product of peracetic oxidation of 163 (Scheme 2.54) was investigated by a single-crystal X-ray analysis, which revealed its actual structure of acetoxybenziodazole 164, which is different from the previously adopted 165 [266],... 

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