ORTEP-3 for Windows - a version of ORTEP-III with a Graphical User Interface (GUI)
01 Oct 1997-Journal of Applied Crystallography (International Union of Crystallography)-Vol. 30, Iss: 5, pp 565-565
TL;DR: L Lists of software presented and~or reviewed in the Journal of Applied Crystallography are available on the World Wide Web at the above address, together with information about the availability of the software where this is known.
Abstract: Computer Program Abstracts The category Computer Program Abstracts provides a rapid means of communicating up-to-date information concerning both new programs or systems and significant updates to existing ones. Following normal submission, a Computer Program Abstract will be reviewed by one or two members of the IUCr Commission on Crystallographic Computing. It should not exceed 500 words in length and should follow the standard format given on page 189 of the June 1985 issue of the Journal [J. Appl. CrysL (1985). 18, 189190] and on the World Wide Web at http://www.iucr. ac. uk/journals/jac/software/. Lists of software presented and~or reviewed in the Journal of Applied Crystallography are available on the World Wide Web at the above address, together with information about the availability of the software where this is known. J. App/. CrysL (1997). 30, 565 ORTEP-3 for Windows a version of ORTEP-III with a Graphical User Interface (GUI)
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TL;DR: Theoretical studies using the Electron Localizability Indicator (ELI-D) suggest the metal-metal bonding is more significant, while the delocalization indices imply that both Fe-Fe bonding and Fe···C(alkylidyne) bonding are equally important.
Abstract: The charge density in the tri-iron methoxymethylidyne cluster Fe3(μ-H)(μ-COMe)(CO)10 (1) has been studied experimentally at 100 K and by DFT calculations on the isolated molecule using the Quantum Theory of Atoms in Molecules (QTAIM). The COMe ligand acts as a nearly symmetric bridge toward two of the Fe atoms (Fe−C = 1.8554(4), 1.8608(4) A) but with a much longer interaction to the third Fe atom, Fe−C = 2.6762(4) A. Complex 1 provides a classic example where topological QTAIM catastrophes render an exact structure description ambiguous. While all experimental and theoretical studies agree in finding no direct metal−metal interaction for the doubly bridged Fe−Fe vector, the chemical bonding between the Fe(CO)4 unit and the Fe2(μ-H)(μ-COMe)(CO)6 moiety in terms of conventional QTAIM descriptors is much less clear. Bond paths implying direct Fe−Fe interactions and a weak interaction between the COMe ligand and the Fe(CO)4 center are observed, depending on the experimental or theoretical density model examin...
89 citations
TL;DR: In this paper, a stereochemical model is proposed to rationalise the crucial role of the substituent in position 5, suitably placed to blind the Si-face of the coordinated reagent.
88 citations
TL;DR: An extensive study of the Fe coordination chemistry of the HPCIH analogues including the first crystallographically characterised Fe(II) complex of these chelators, which indicates that their Fe chelation efficacy is due, at least in part, to the fact that these ligands and their Fe( II) complexes are neutral at physiological pH (7.4) and sufficiently lipophilic to permeate cell membranes.
Abstract: The potentially tridentate ligand 2-pyridinecarbaldehyde isonicotinoyl hydrazone (HPCIH) and its analogues are an emerging class of orally effective Fe chelators that show great promise for the treatment of Fe overload diseases. Herein, we present an extensive study of the Fe coordination chemistry of the HPCIH analogues including the first crystallographically characterised FeII complex of these chelators. Unlike most other clinically effective Fe chelators, the HPCIH analogues bind FeII and not FeIII. In fact, these chelators form low-spin bis-ligand FeII complexes, although NMR suggests that the complexes are close to the high-spin/low-spin crossover. All the Fe complexes show a high potential FeIII/II redox couple (> 500 mV vs. NHE) and cyclic voltammetry in aqueous or mixed aqueous/organic solvents is irreversible as a consequence of a rapid hydration reaction that occurs upon oxidation. A number of the HPCIH analogues show high activity at inducing Fe efflux from cells and also at preventing Fe uptake by cells from the serum Fe transport protein transferrin. As a class of ligands, these chelators are more effective at reducing Fe uptake from transferrin than inducing Fe mobilisation from cells. This may be related to their ability to intercept FeII after its release from transferrin within the cell. Our studies indicate that their Fe chelation efficacy is due, at least in part, to the fact that these ligands and their FeII complexes are neutral at physiological pH (7.4) and sufficiently lipophilic to permeate cell membranes.
88 citations
TL;DR: In this paper, the crystal structures and spectroscopic properties of monomeric, dimeric and polymeric copper(II) chloroacetates with isonicotinamide (INA), N-methylnicotinamide(MNA), and N,N-diethylnicotine (DENA) were characterized by electron paramagnetic resonance (EPR) and IR spectroscopy.
88 citations
TL;DR: In this paper, variable temperature single crystal neutron diffraction has been used to examine the behavior of protons in the structure of acetylsalicylic acid (Aspirin).
Abstract: Variable temperature single crystal neutron diffraction has been used to examine the behaviour of protons in the structure of acetylsalicylic acid (Aspirin). The neutron diffraction study, at seven temperatures between 20 and 300 K, has allowed a full description of the molecular structure and the intermolecular interactions in the material and their variation with temperature. In particular the variable temperature studies have allowed the full description of the apparent torsional motions of the terminal methyl group, which exhibit characteristic substantial zero-point motion. The extracted values for the barrier height for the cosine potential governing this motion are found to be in good agreement with that found from ab initio calculations and are compared with those found in a range of other materials. Our previously postulated empirical method for correcting bond lengths in such a case is once again found to have some validity. The data also yield a full description of the various hydrogen bonds present, notably the direct observation of likely anharmonicity in the potential governing the hydrogen bond in the carboxylic acid dimer motif. The availability of data at various temperatures is found to be important in identifying this effect, and in discriminating between alternative explanations of the observed structural parameters. The direct images of protons in various hydrogen bonding potentials, calculated from the neutron data, are also found to be valuable in this context.
88 citations