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The structures of tricarbonyl(formylcyclopentadienyl)manganese(I), [Mn(C6H5O)(CO)3], (I), and tricarbonyl(formylcyclopentadienyl)rhenium(I), [Re(C6H5O)(CO)3], (II), were determined at 100 K. Compounds (I) and (II) both possess a carbonyl group in a trans position relative to the substituted C atom of the cyclopentadienyl ring, while the other two carbonyl groups are in almost eclipsed positions relative to their attached C atoms. Analysis of the intermolecular contacts reveals that the molecules in both compounds form stacks due to short attractive π(CO)...π(CO) and π(CO)...π interactions, along the crystallographic c axis for (I) and along the [201] direction for (II). Symmetry-related stacks are bound to each other by weak intermolecular C-H...O hydrogen bonds, leading to the formation of the three-dimensional network. [ABSTRACT FROM AUTHOR]

The geometrical preferences of hydrogen bonds with azide anion are studied using topological analysis of experimental and calculated electron density distribution. The comparison of electron localization function (ELF) and QTAIM analysis shows the reasons behind the apparent unidirectionality of azide anion's lone pairs. The similarity between hydrogen and coordinated bonds involving azide species is demonstrated viathe analysis of the CSD. [ABSTRACT FROM AUTHOR]

The article discusses a study on the crystal and molecular structures of monohalogenated ferrocenes C5H5FeC5H4X (X = Cl, Br and I) and a second polymorph of C5H5FeC5H4I. It describes the 1-chloroferrocene and 1-bromoferrocenes as isomorphous crystals. The arrangement of molecules in the triclinic form of 1-iodoferrocene is in zigzag tetramers. Crystallographic data shows the stability of the monoclinic form.

Abstract: In the course of searching for new acentric NLO crystalline materials, three chiral (2S)-2-(methoxymethyl)pyrrolidine derivatives were synthesized. The introduction of chiral fragments into the structures of NLO chromophores was expected to bring acentricity to the resulting crystalline materials. The presence of intermolecular H-bonds in the crystal structures of two of the compounds was expected to elevate their melting points compared to the third one and to facilitate crystallization with orientation of molecules in the crystals favorable for SHG. Three compounds of this type have been prepared and for all of them single crystals have been grown and characterized by X-ray analysis. Indeed, all investigated compounds crystallized in acentric space groups. Significant elevation of melting temperatures was found for the two compounds possessing intermolecular H-bonds. In the two compounds molecules form one-dimensional H-bonded associates (ribbons). These ribbons are located in parallel planes in one structure and go along two different crystallographic directions in the other one. The third compound does not form any supramolecular aggregates in crystals. [Copyright &y& Elsevier]

The crystal structures of Cr(PhCN)2 (2), (PhCN)Cr(PhCH3) (3) and (PhCN)Cr(PhCF3) (4) prepared by means of the Metal Vapor Synthesis (MVS) technique have been determined. Compounds (2), (3) and (4) crystallize as discrete sandwich complexes having intrinsic C2v(mm2), C5(m) and C1(1) symmetries, respectively. The X-ray diffraction study has revealed a synperiplanar conformation for (2) and (3), and a synclinal conformation for (4) with a torsion angle (Cipso1-Centroid1-Centroid2-Cipso2) of φ = 63.5°. The angles between the ligand planes are 2.2, 3.9 and 1.8°, respectively. The Cr atom is slightly (by 0.04-0.06 Å) displaced towards the substituents from the line connecting the centers of the opposite aromatic rings. The Cr-Cipso distances are 2.115 (2)-2.137 (2), 2.112 (2) and 2.185 (3) Å for CN, CF3 and CH3 groups, respectively. The CN groups as well as the H atoms lie out of the C6 ring planes and are bent towards the Cr atom, but the C atom of the CH3 group also lying out of the C6 ring plane is bent away from the Cr atom. The C atom of the CF3 group is essentially coplanar to the C6 ring plane. There are no unusual intermolecular contacts in the structures of (2)-(4). [ABSTRACT FROM AUTHOR]

The novel title furazan-containing macrocycle (systematic name: 6,9,14,17-tetraoxa-2,3,5,7,16,18-hexaazatricyclo[13.3.0.- 04.8]octadeca-4,7,15,18-tetraene), C8H10N6O4, (I), is the first macrocycle where the furazan rings are connected via a hydrazine group. In spite of the strain in the 12-membered macrocycle of (I), the geometry of the furazan fragment is the same in (I) and in its acyclic analogue 1,8-bis(5-aminofurazan-4-yloxy)-3,6-dioxaoctane, C10H16N6O6, (II). In both compounds, the participation of the furazan rings in intermolecular hydrogen bonding equalizes the N-O bonds within the furazan rings, in contrast with rings which do not participate in such interactions. [ABSTRACT FROM AUTHOR]

Detailed analysis of the charge density distribution function in the crystal of L-nitroarginine with two crystallographycally distinct molecules using Richard Bader''s ‘Atoms in Molecules’ theory demonstrated the strengthening of hydrogen bonds owing to cooperativity effects and revealed the role of H-bonding in charge transfer in a structurally frustrated system. [Copyright &y& Elsevier]

The molecular and crystal structure of three germatrane compounds: 1-(1-bromobicyclo[4.1.0]hept-7-yl)germatrane, l-(1-trimethylsilanyl-cyclopropyl)-germatrane and 1-(1-Methyl-1,2-dicarba-closo-dodecaboranyl)germatrane has been determined by X-ray diffraction method in order to investigate main geometrical regularities of the germatrane molecules. There were established all values of the main structural parameters above-mentioned molecules. [Copyright &y& Elsevier]

A remetalation (a capping group exchange) reaction of the boronantimony-capped iron(II) clathrochelates with zirconium and hafnium(IV) phthalocyanines in CH2Cl2/CH3OH medium afforded the hybrid phthalocyaninoclathrochelates in a practically quantitative yield. The complexes obtained have been characterized both on the basis of elemental analysis, PD mass spectrometry, IR, UVvis, 57Fe Mössbauer, and NMR spectroscopies, and crystallographically. An encapsulated iron(II) ion in an intermediate between a trigonal-prismatic and a trigonal-antiprismatic environment of six nitrogen atoms of the macrobicyclic ligand was found to be in a Iow-spin state. The cyclic voltammograms show irreversible oxidation and reduction waves assignable to Fe3+/Fe2+ couples of macrobicyclic fragments and to phthalocyanine macrocycles. [ABSTRACT FROM AUTHOR]

A water-soluble nitrosyl complex of iron {Fe2[S(CH2)2NH3]2(NO)4}SO4·2.5H2O, belonging to a structural type ‘μ2-S’ and containing a ligand of natural origin, cysteamine, was synthesised and studied by X-ray crystallography, IR and Mössbauer spectroscopy. [Copyright &y& Elsevier]