J. Appl. Cryst.の発刊に際して

This paper describes the validation of a dispersion-corrected density functional theory (d-DFT) method for the purpose of assessing the correctness of experimental organic crystal structures and enhancing the information content of purely experimental data. 241 experimental organic crystal structures from the August 2008 issue of Acta Cryst. Section E were energy-minimized in full, including unit-cell parameters. The differences between the experimental and the minimized crystal structures were subjected to statistical analysis. The r.m.s. Cartesian displacement excluding H atoms upon energy minimization with flexible unit-cell parameters is selected as a pertinent indicator of the correctness of a crystal structure. All 241 experimental crystal structures are reproduced very well: the average r.m.s. Cartesian displacement for the 241 crystal structures, including 16 disordered structures, is only 0.095 A (0.084 A for the 225 ordered structures). R.m.s. Cartesian displacements above 0.25 A either indicate incorrect experimental crystal structures or reveal interesting structural features such as exceptionally large temperature effects, incorrectly modelled disorder or symmetry breaking H atoms. After validation, the method is applied to nine examples that are known to be ambiguous or subtly incorrect.

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Validation of experimental molecular crystal structures with dispersion-corrected density functional theory calculations

There are very few people who have lived the allotted time but have an interesting biography, and there are very few congregations but have a very profitable history. The church at Leiper’s Fork, now known as Hillsboro, TN, has a most interesting history. There are few, if any, who know the history of their congregation. It seems that it would be encouraging to the congregation if its history would be kept fresh in the minds of its members.

A Short History Of...

Homo- and heteronuclear group 12 metal (Zn2+, Cd2+, and Hg2+) complexes 1–6 containing a newly designed 18-membered N2O2S2 macrocycle incorporating two pyridine subunits (L) were prepared and structurally characterized. The individual complexes isolated exhibit unusual stoichiometries, geometries, oxidation states, and structural topologies and include an infinite mercurous complex and a heteronuclear dumbbell-shaped complex. Both the Zn(II) complex [Zn(L)][ZnBr4] (1) and the Cd(II) complex [Cd(L)Br2] (2) are mononuclear, with the metal ion located inside the macrocyclic cavity. The six-coordinated Zn(II) center in 1 adopts an octahedral geometry and is shielded from the anion and solvent by the strongly bound macrocycle. The Cd(II) center in 2 is seven-coordinate, being bound equatorially to two N donors, two O donors, and a S donor from the macrocycle and axially to two bromide ions on opposite sides of the macrocyclic plane, adopting a pentagonal-bipyramidal geometry. In the Hg(II) complexations, the c...

Group 12 Metal Complexes of an 18-Membered N2O2S2 Macrocycle Incorporating Two Pyridines: First Examples of an Infinite Mercury(I) Complex and a Dumbbell-Shaped Heteronuclear Complex with a Macrocyclic Ligand

Conformational stability, spectroscopic (FT-IR, FT-Raman and UV-Vis) analysis, NLO, NBO, FMO and Fukui function analysis of 4-hexylacetophenone by density functional theory.

Two dinuclear succinato-bridged nickel(II) complexes [Ni(RR-L)]2(μ-SA)(ClO4)2 (1) and [Ni(SS-L)]2(μ-SA)(ClO4)2 (2) (L = 5, 5, 7, 12, 12, 14-hexamethyl-1, 4, 8, 11-tetraazacyclotetradecane, SA = succinic acid) were synthesized and characterized by EA, Circular dichroism (CD), as well as IR and UV/Vis spectroscopy Single crystal X-ray diffraction analyses revealed that the NiII atoms display a distorted octahedral coordination arrangement, and the succinato ligand bridges two central NiII atoms in a bis bidentate fashion to form dimers in 1 and 2 The monomers of {[Ni(RR-L)]2(μ-SA)}2+ and {[Ni(SS-L)]2(μ-SA)}2+ are connected by O–H···O and N–H···O hydrogen bonds into a 1D right-handed and left-handed helical chain along the b axis, respectively The homochiral natures of 1 and 2 are confirmed by the results of CD spectroscopy

Synthesis and Crystal Structure of Two Succinato-Bridged Macrocyclic Nickel(II) Complexes

The reactions of a racemic four-coordinate Ni(II) complex [Ni(rac-L)](ClO4)2 with l- and d-alanine in acetonitrile/water gave two six-coordinate enantiomers formulated as [Ni(RR-L)(l-Ala)](ClO4)·2CH3CN (1) and [Ni(SS-L)(d-Ala)](ClO4) (2) (L = 5,5,7,12,12,14-hexamethyl-1,4,8,11-tetraazacyclo-tetradecane, Ala− = alanine anion), respectively. Evaporation from the remaining solutions gave two four-coordinate enantiomers characterized as [Ni(SS-L)](ClO4)2 (S-3) and [Ni(RR-L)](ClO4)2 (R-3), respectively. Single-crystal X-ray diffraction analyses of complexes 1 and 2 revealed that the Ni(II) atom has a distorted octahedral coordination geometry, being coordinated by four nitrogen atoms of L in a folded configuration, plus one carboxylate oxygen atom and one nitrogen atom of l- or d-Ala− in mutually cis-positions. Complexes 1 and 2 are supramolecular stereoisomers, constructed via hydrogen bonding between [Ni(RR-L)(l-Ala)]+ or [Ni(SS-L)(d-Ala)]+ monomers to form 1D hydrogen-bonded zigzag chains. The homochiral natures of complexes 1 and 2 have been confirmed by CD spectroscopy.

Chiral resolution of l- and d-alanine and a racemic macrocyclic nickel(II) complex: synthesis and crystal structures

C12H13ClO4, monoclinic, C2/c (no. 15), a = 35.310(2) A, b = 5.9993(2) A, c = 22.7422(8) A, = 98.692(4)°, V = 4762.3 A, Z = 16, Rgt(F) = 0.0397, wRref(F ) = 0.1048, T = 153 K.

Crystal structure of 2-(4-chlorophenyl)-5-methyl-1,3-dioxane-5-carboxylic acid, C12H13ClO4

In the title compound, C12H13ClO4, the 1,3-dioxane ring adopts a chair conformation and the 2-chloro­benzene and methyl substituents occupy equatorial sites. The carboxyl group is in an axial inclination. In the crystal, carb­oxy­lic acid inversion dimers linked by pairs of O—H⋯O hydrogen bonds generate R22(8) loops.

https://journals.iucr.org/e/issues/2012/07/00/hb6799/hb6799.pdf

2-(2-Chloro-phen-yl)-5-methyl-1,3-dioxane-5-carboxylic acid.

The title compound, [Co(C4H13N3)2][Co(CN)6]·2H2O, comprises one [Co(dien)2]3+ cation (dien is diethyl­ene­triamine), one [Co(CN)6]3− anion and two water molecules. The Co3+ atom of the [Co(dien)2]3+ cation is six-coordinated by six N atoms from two diethyl­enetriamine groups. The Co3+ atom of the [Co(CN)6]3− anion is six-coordinated by six C atoms from six cyanide ions. Neighboring cations and anions are connected by hydrogen bonds to each other and to the water molecules. The metal atoms lie on inversion sites.

Xian-You Yuan

Papers

Synthesis and Crystal Structure of Two Succinato-Bridged Macrocyclic Nickel(II) Complexes

Chiral resolution of l- and d-alanine and a racemic macrocyclic nickel(II) complex: synthesis and crystal structures

Crystal structure of 2-(4-chlorophenyl)-5-methyl-1,3-dioxane-5-carboxylic acid, C12H13ClO4

2-(2-Chloro-phen-yl)-5-methyl-1,3-dioxane-5-carboxylic acid.

Bis(diethylenetriamine)cobalt(III) hexacyanocobaltate(III) dihydrate