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The crystal structures of two polymorphs of a phenazine hexacyanoferrate(II) salt/cocrystal, with the formula (Hphen)3[H2Fe(CN)6][H3Fe(CN)6]·2(phen)·2H2O, are reported. The polymorphs are comprised of (Hphen)2[H2Fe(CN)6] trimers and (Hphen)[(phen)2(H2O)2][H3Fe(CN)6] hexamers connected into two‐dimensional (2D) hydrogen‐bonded networks through strong hydrogen bonds between the [H2Fe(CN)6]2− and [H3Fe(CN)6]− anions. The layers are further connected by hydrogen bonds, as well as through π–π stacking of phenazine moieties. Aside from the identical 2D hydrogen‐bonded networks, the two polymorphs share phenazine stacks comprising both protonated and neutral phenazine molecules. On the other hand, the polymorphs differ in the conformation, placement and orientation of the hydrogen‐bonded trimers and hexamers within the hydrogen‐bonded networks, which leads to different packing of the hydrogen‐bonded layers, as well as to different hydrogen bonding between the layers. Thus, aside from an exceptional number of symmetry‐independent units (nine in total), these two polymorphs show how robust structural motifs, such as charge‐assisted hydrogen bonding or π‐stacking, allow for different arrangements of the supramolecular units, resulting in polymorphism. [ABSTRACT FROM AUTHOR]

The reactions of N -arylalkyl derivatives of iminodiacetamide (Bnimda, Peimda, Ppimda; Bn = benzyl, Pe = 2-phenylethyl; Pp = 3-phenylprop-1-yl) with copper(II) sulfate and sodium perchlorate in aqueous solutions were investigated. Three new copper(II) complexes [Cu(Bnimda) 2 ](ClO 4 ) 2 ( 1 ), [Cu(Peimda) 2 ](ClO 4 ) 2 ( 2 ) and [Cu(Ppimda) 2 ](ClO 4 ) 2 ·2H 2 O ( 3 ) were prepared and characterized by infrared spectroscopy and thermal analysis (TG/DTA). Complex 2 was found to be explosive upon heating. The octahedral coordination environments around the copper(II) ions in complexes 1 and 3 consist of two O , N , O ′-tridentate N -arylalkyliminodiacetamide ligands, with imino N atoms in trans -position. Molecules are interconnected by extensive hydrogen bonding between the amide moieties and perchlorate ions or water molecules, forming 3D networks in both structures. However, the difference in the hydrophobic chain lengths leads to significant differences in the hydrogen bonding motifs in the two structures. The molecular geometry and infrared spectra of these complexes were also studied by DFT calculations using B3LYP/6-311G(d,p) computational model. The calculated spectra and molecular geometry agree very well with the experimental results despite the extensive hydrogen bonding frameworks which are present in the crystal structures of these compounds. [ABSTRACT FROM AUTHOR]

Highlights: [•] Five 1,3,3′-triketones derived from dipivaloylmethane have been prepared. [•] Both in the solid and in solution no enol tautomers were detected for any of the compounds. [•] Slow isotopic exchange in CD3OD solution indicates presence of a minute amount of the enol. [•] The predominance of the triketo tautomer is attributed to steric hindrance in enol molecules. [ABSTRACT FROM AUTHOR]

A survey of the Cambridge Structural Database (CSD) revealed the existence of a new supramolecular homosynthon in oxovanadium coordination compounds (OCCs) that is based on non-covalent V=O…C interactions. V=O…C close contacts were found in 38.7% of structures containing vanadyl or pervanadyl groups. The V=O…C interaction is clearly distinguishable from a putative V=O…H–C hydrogen bond upon analysis of OCC crystal structures deposited in the CSD. In the majority of structures, the OCCs assemble to form dimers or polymers. The V=O…C interactions were also found to lead to self-assembly of two new oxovanadium β-diketonate complexes into dimers in the solid state. [ABSTRACT FROM AUTHOR]

A series of 22 salts and co-crystals of gentisic acidand pyridinederivatives were synthesized and their crystal structures were studiedby X-ray diffraction. The proton transfer was found to to be absentwhen the difference in pKavalues wasbelow 2, and it always occurred when it was above 2.5. The hydrogenbonds between the carboxylic group and pyridine nitrogen atom werefound in all structures but one. These hydrogen bonds are shorterand apparently stronger in co-crystals than in salts. In the structuresof salts the most significant intermolecular interaction is hydrogenbonding between anions, usually leading to chains or dimers, whereasin co-crystals the direct bonding between neutral gentisic acid moleculesis mostly absent. Using 4,4′-bipyridine, two desmotropes wereobtained in which the difference in hydrogen bonding of gentisic acidmolecules leads to different protonation in two structures. [ABSTRACT FROM AUTHOR]

Morpholine adducts of nickel(II), cobalt(II), and manganese(II) benzoylacetonates, as well as a morpholine solvate of manganese(II) benzoylacetonate, were prepared and characterized by X-ray diffraction and thermal analysis. All four compounds crystallize in the P2/ c space group with two complex molecules per unit cell. The morpholine solvate, along with the two adduct molecules, also contains four solvent morpholine molecules in the unit cell. The non-solvate compounds are isostructural, with crystal structures comprising 2D networks formed by C-H···O hydrogen bonding between phenyl rings and morpholine oxygen atoms. The topology of these networks can be described as intersecting C(24) chains forming R(48) rings. Networks with the same topology are also present in the solvate, but they are heavily distorted due to the presence of solvent morpholine molecules. Thermogravimetric analysis shows similar behavior of the non-solvate compounds upon thermal decomposition, with three degradation steps which can be related to gradual loss of morpholine molecules and subsequent overall decomposition. Decomposition of the solvate also proceeds in several steps, the first of which can be related to loss of solvent morpholine molecules and the further steps are analogous to those in the non-solvate compounds. [ABSTRACT FROM AUTHOR]

Tetrakis(benzoylacetonato)cerium(IV), [Ce(bzac)4] and triethylammonium tetrakis(benzoylacetonato)lanthanate(III) tetrahydrate, [Et3NH][La(bzac)4] · 4H2O were prepared and characterized by TG and DCS measurements, IR spectroscopy, and X-ray structure analysis. The coordination polyhedron of cerium is a trigonal dodecahedron, while that of lanthanum is a distorted square antiprism. Thermal and spectroscopic measurements indicate that bonding of the ligand to metal is stronger in [Ce(bzac)4] than in [La(bzac)4]-. [ABSTRACT FROM AUTHOR]

Abstract: The crystal structure of [4‐damp])2[Cl4Q]3 (4‐damp=4‐dimethylamino‐N‐methylpyridinium, Cl4Q=tetrachloroquinone) salt is built up from slipped columnar stacks of quinoid rings composed of closely bound trimers with the intra‐trimer separation distance of 2.84 Å and total charge of −2 whereas the inter‐trimer distance is 3.59 Å. The individual rings exhibit partial negative charges that are distributed unevenly among the three Cl4Qs in the trimer. The strong interactions within a trimer (Cl4Q)32− have a partially covalent character with two‐electron/multicentered bonding, that is extended over three rings, plausibly termed as “pancake bonding”. The electron pairing within this multicentre bond leads to the fact that the crystals are diamagnetic and act as insulators. The studies of the structure and nature of bonding are based on X‐ray charge density analysis and density functional theory. [ABSTRACT FROM AUTHOR]

The structural parameters and semiconductivity of crystals with stacked 5,6-dichloro-2,3-dicyanosemiquinone (DDQ) radicals were studied for a series of the first nine salts of DDQ with substituted N-ethyl- and N-methylpyridinium cations. Structures with stacks of equidistant radicals (interplanar separation ＜3.3 Å) are fairly good semiconductors (10−9 S cm−1), while those with Peierls-distorted stacks comprising diamagnetic dimers of radicals (interplanar separations are ＜3.1 Å within the dimers and ＞3.4 Å between the dimers) are insulators. DFT calculations indicate the covalent character (pancake bonding) of the interactions between the DDQ radical anions. The inductive effects of electronegative substituents (halogeno and cyano) on the quinoid ring stabilise the radicals, but also increase the HOMO–LUMO gap, resulting in lower electrical conductivity. [ABSTRACT FROM AUTHOR]