Search

The structure of the new salt 1-(o-tolyl)biguanidium chloride, C9H14N5 +·Cl−, has been determined by single-crystal X-ray diffraction. The salt crystallizes in the monoclinic space group C2/c. In this structure, the chloride and biguanidium hydrophilic ions are mostly connected to each other via N—H...N and N—H...Cl hydrogen bonds to form layers parallel to the ab plane around y = 1 \over 3 and y = 2 \over 3. The 2-methylbenzyl groups form layers between these layers around y = 0 and y = 1 \over 2, with the methyl group forming C—H...π interactions with the aromatic ring. Intermolecular interactions on the Hirshfeld surface were investigated in terms of contact enrichment and electrostatic energy, and confirm the role of strong hydrogen bonds along with hydrophobic interactions. A correlation between electrostatic energy and contact enrichment is found only for the strongly attractive (N—H...Cl−) and repulsive contacts. Electrostatic energies between ions reveal that the interacting biguanidium cation pairs are repulsive and that the crystal is maintained by attractive cation...Cl− dimers. The vibrational absorption bands were identified by IR spectroscopy.

The chemical preparation, characterization by single-crystal X-ray diffraction, elemental analysis and IR spectroscopy of the new Fe(III) complex (C5H7.50N3O)2[FeCl4] are reported. The Fe(III) cation is four-coordinated, in tetrahedral fashion, by four chlorine atoms. The [FeCl4]− tetrahedra are located parallel to the (a, b) plane at z = ¼ (2n + 1) between layers of organic cations (C5H7.50N3O)2+. The FeCl4 moieties are inserted between these planes by establishing N–H...Cl and C–H…Cl hydrogen bonds generated by amino and methyl groups as donors and Cl− anions as acceptors to form a three-dimensional network. The organic groups are linked together by N–H...N hydrogen bonds to form chains extending along the [110] direction. These chains are arranged in planes parallel to (a, b) at z = ½n. Intermolecular contacts on the Hirshfeld surface were investigated statistically. The most favored and stabilizing contacts are the strong (N–H…Cl−, N–H…N) hydrogen bonds as well as the weaker ones C–H…Cl−. The vibrational absorption bands were identified by infrared spectroscopy. Electronic properties such as HOMO and LUMO energies were also derived.

Two novel complexes, [(C

The authors have requested that this preprint be removed from Research Square.

International audience; The physicochemical properties of a 33 isomer grid of mono-chlorobenzamides (Clxx) are reported with comprehensive studies of their crystal structures and interaction environments (Clx = para-/meta-/ortho-chlorobenzoyl and x = para-/meta-/ortho-aminopyridine substitutions). The nine compound Clxx series was synthesised from the three p-/m-/o-chlorobenzoyl chlorides and three p-/m-/o-aminopyridine isomers using standard synthetic procedures. Clxx exhibits some similarities to the related Fxx and Brxx congeners e.g. the isomorphous behaviour of Clpp (para-Chloro-N'-(para-pyridyl)benzamide) with several close relatives, and there are five isomorphous pairs of Clxx and Brxx crystal structures. Notably Clmp and Clpm both crystallise with Z'=4 in space group P but show important differences. The overall lack of isomers crystallising with solvate molecules is noteworthy, except for Clmm(H 2 O). In all Clxx crystal structures, strong N-H…N hydrogen bonds form, however, Clpo also crystallises as the unexpected Clpo_O polymorph with N-H…O=C intermolecular hydrogen bonding. The Clxo triad (with ortho-pyridines) exhibits the expected cyclic N-H…N dimer formation with R 2 2 (8) hydrogen bonded rings. The H C atom type, forming weak C-H…Cl hydrogen bonds, is the only favoured interaction partner of chlorine in Clxx. Conformational analyses (gas phase) together with crystal contact enrichment studies place Clxx in context and at the interface of hydrogen and halogen bonding interactions, though strong hydrogen bonding dominates. In Clxx the interaction energies with nearest neighbours are shown to contribute to most of the lattice electrostatic energies. The melting temperatures T m show correlation with both molecular symmetry (Carnelley's rule) and total electrostatic energy of the weak interactions; in addition, these T m values can be well predicted from a linear fit combining both descriptors. In Clxx, N-H…N hydrogen bonds dominate, largely in the absence of solvates, and with five Clxx forming isomorphous pairs with Brxx analogues; Clpp being isomorphous with several close benzamide relatives. Analysis of T m reveals correlations involving both symmetry and electrostatic energies.

The advancement in 3D electron diffraction (3D ED) techniques that lead to a revolution in molecular structure determination using nano-sized crystals is now achieving atomic resolution. The structures can be obtained from 3D ED data with tools similar to those used for X-ray structure determination. In this context, the MoPro software, originally designed for structure and charge density refinements using X-ray diffraction data, has been adapted. Structure refinement on 3D ED data was achieved via implementation of electron scattering factors available in the literature and by application of the Mott–Bethe equation to X-ray scattering factors computed from the multipolar atom model. The multipolar model was parametrized using the transferable pseudoatom databanks ELMAM2 and UBDB. Applying the independent atom model (IAM), i.e. spherical neutral atom refinement, to 3D ED data on β-glycine in MoPro resulted in structure and refinement statistics comparable to those obtained from other well known software. Use of the transferred aspherical atom model (TAAM) led to improvement of the refinement statistics and a better fit of the model to the 3D ED data as compared with the spherical atom refinement. The anisotropic displacement parameters of non-H atoms appear underestimated by typically 0.003 Å2 for the non-H atoms in IAM refinement compared with TAAM. Thus, MoPro is shown to be an effective tool for crystal structure refinement on 3D ED data and allows use of a spherical or a multipolar atom model. Electron density databases can be readily transferred with no further modification needed when the Mott–Bethe equation is applied.

A new compound of cadmium (II), [(Cd(2,3-pdcH)3) (Cd(H2O)6)], has been synthesized by reaction of 2,3-pyridine dicarboxylic anhydride with cadmium dichloride. The title compound has been characterized by X-ray crystallography and theoretical chemistry calculations. The new coordinated compound crystallizes in the trigonal space group P3. Its crystal structure consists of two homoleptic cadmium species which are showing a distorted octahedral geometry, one with six water molecules and the other one with three organic ligands coordinated to cadmium by the nitrogen atom of the pyridine ring and one oxygen atom from the deprotonated dicarboxylic acid group. The different intermolecular interactions were defined by Hirshfeld surface analyses and described in terms of electrostatic energy. O-H…O hydrogen bonds between the water molecules and the carboxylate groups are formed and stabilized the crystal packing. Also, hydrophobic contacts consist between the pyridine cycle and the carboxylic/carboxylate functions. The HOMO and LUMO orbitals and the Molecular Electrostatic Potential maps were performed by the use of DFT theoretical calculations.

International audience; An introduction to Multipole Modelling The surrounding chapters in this book highlight the pivotal role of the charge distribution in the qualitative and quantitative characterization of chemical bonds, and in the determination of molecular and crystal properties. Hence, the motivation to obtain accurate analytical models of the charge distribution, that arises from the electron density (ED).. Providing such models is the aim of the multipole modelling, summarized in this section. Next, the XD and Mo-ProSuite programs, two among the most widely used packages in charge density analysis, will be described. These programs utilize the multipolar atom model and allow the determination, representation, and the property analysis of electron densities in crystal structures-be they molecular, polymeric, ionic or elemental, including metals. It is well known that crystal structures can be determined by the means of single crystal Xray diffraction experiments. As X-rays interact with electrons, diffraction experiments image

In this paper, we report preparation and structure determination of two new adeninium-based hybrid compounds formed with selenious acid: adeninium hydrogen diselenite (I) and adeninium hydrogen selenite (II). Single crystals of (I) and (II) were obtained by slow evaporation and their X-ray structures are reported coupled with a quantum chemical density functional theory (DFT) studies. In the atomic arrangement, the different entities are held together through N/O—H···O, N—H···N and C—H···N/O hydrogen bonds on the Watson−Crick, Hoogsteen and sugar sites. Their overall three-dimensional architectures are mostly controlled by electrostatic interactions between the inorganic anion and organic cation frameworks and by hydrogen bonding. Furthermore, the crystal structures of (I) and (II) contain supramolecular homo and heterosynthons which are present in most similar structures. The similarities and subtle differences of the intermolecular interactions in the two crystal structures have been investigated and discussed using Hirshfeld surface analysis, fingerprint plots, and contact enrichment. The theoretical results are in good relation with the experimental structural analysis and confirm that the charge transfer occurs from inorganic anions to organic cations.

One novel organic-inorganic hybrid supramolecular compound named Adeninium orthoperiodate (1−) bis(hydrate) (I) has been synthesized and characterized by FT-IR spectroscopy and single-crystal X-ray diffraction complemented with a quantum chemical study performed with DFT method at the B3LYP/3–21G level. The title compound crystallized in the monoclinic centrosymmetric P 21/n space group. In the molecular arrangement, the different entities are held together through the interplay of intermolecular O···H N/O and N H···O hydrogen bonds, that found to be effective in stabilizing the three-dimensional crystal packing. The hydrogen bonds network of (I) contains an interesting cyclic homosynthon of R 2 2 (10) graph set notation involving the adeninium Hoogsteen sites (N6—H1N···N7). The role of such interactions is known to be predominant in the stabilization of the usual 1H,9H tautomer. The different intermolecular interactions of (I) were quantified and analysed using Hirshfeld surface analysis, enrichment ratio (E) and fingerprint plots. The obtained results indicate that the main contributions are ascribed to O···H and H···H interactions. Scanning electron microscopy (SEM) was used to provide an extremely enlarged image of the sample morphology of (I), as well as information on its chemical composition using an energy dispersive X-ray spectrometer (EDS) detector, which confirms that the compound was successfully synthesized. The complementary theoretical achievements were found in a good agreement with respect to the experimental data. Moreover, a natural bond orbital (NBO) analysis was performed to evaluate the nature of bonding and the strength of the intra and inter-molecular interactions. Furthermore, the calculations of HOMO and LUMO energies were carried out to investigate the charge transfer within the molecular structure. The molecular electrostatic potential maps were used to detect the possible electrophilic and nucleophilic sites in (I).

International audience; The crystal structure of lithium 2,5-dihydroxyquinonate dihydrate bis(dimethylsulfoxide) solvate [Li2DHQ(H2O)2(DMSO)2] reveals a close contact between the lone pair on the electropositive S atom of DMSO and the dianionic quinoid ring. This contact, resembling a π-hole interaction involving a dianion as an acceptor was studied in detail by a combination of X-ray charge density and quantum chemical modelling. Topology of electron density reveals a bond path and a (3,-1) critical point between the S atom of the DMSO and a C atom of the quinoid ring, while analysis of electrostatic potential indicates that the interaction between these two atoms is repulsive. However, the global electrostatic interaction between the DMSO and the dihydroxyquinonate moieties is attractive (-19.1 kJ/mol), as well as total in vacuo interaction energy (-42.8 kJ/mol).

International audience; A novel hybrid organic-inorganic molecular solid, 1-(4-methoxyphenyl)piperazinium (1–4MPPip) tetra(isothiocyanate)cobalt monohydrate (1–4MPPip)4[Co(NCS)4]2•H2O (I), was prepared using a slow evaporation growth technique at room temperature and characterized by elemental analysis, X-ray crystal structure, spectroscopic and computational studies. The crystal structural analysis reveals that the solid crystallizes in the triclinic space group P1. The [Co(NCS)4]2− anions are arranged in pairs along the c-axis direction to form anionic layers parallel to the (a,c) plane. Intermolecular interactions were investigated by Hirshfeld surfaces and contact enrichment tools. The organic entities are grouped into dimers through weak interactions OW-H…N and OW-H…O generated by the water molecules. The robustness of the crystal is also enhanced by Csingle bondH…π and Csingle bondH…S intermolecular interactions. Mulliken charge distribution, molecular electrostatic potential (MEP) maps and HOMO and LUMO energy gaps have been computed. The vibrational absorption bands were identified by infrared spectroscopy. The solid-state UV-Visible absorption spectrum of the title compound was obtained at room temperature in order to spotlight the optical properties.

The mutual penetration of electron densities between two interacting molecules complicates the computation of an accurate electrostatic interaction energy based on a pseudo-atom representation of electron densities. The numerical exact potential and multipole moment (nEP/MM) method is time-consuming since it performs a 3D integration to obtain the electrostatic energy at short interaction distances. Nguyen et al. [(2018), Acta Cryst. A74, 524–536] recently reported a fully analytical computation of the electrostatic interaction energy (aEP/MM). This method performs much faster than nEP/MM (up to two orders of magnitude) and remains highly accurate. A new program library, Charger, contains an implementation of the aEP/MM method. Charger has been incorporated into the MoProViewer software. Benchmark tests on a series of small molecules containing only C, H, N and O atoms show the efficiency of Charger in terms of execution time and accuracy. Charger is also powerful in a study of electrostatic symbiosis between a protein and a ligand. It determines reliable protein–ligand interaction energies even when both contain S atoms. It easily estimates the individual contribution of every residue to the total protein–ligand electrostatic binding energy. Glutathione transferase (GST) in complex with a benzophenone ligand was studied due to the availability of both structural and thermodynamic data. The resulting analysis highlights not only the residues that stabilize the ligand but also those that hinder ligand binding from an electrostatic point of view. This offers new perspectives in the search for mutations to improve the interaction between the two partners. A proposed mutation would improve ligand binding to GST by removing an electrostatic obstacle, rather than by the traditional increase in the number of favourable contacts.

International audience; We report herein the synthesis of new derivatives of dihydropyrimidine on the basis of 2,4,6-trimetoxybenzaldehyde, which was further regioselectively oxidized in the presence of cerium ammonium nitrate (CAN) with the formation of 5-acetyl-6-methyl-4-(2,4,6trimethoxyphenyl)pyrimidin-2(1H)-one. The structures of both novel compounds were investigated by NMR, mass spectroscopy methods. The structure of the dihydropyrimidine compound 4 was also investigated by X-ray single crystal diffraction method. In order to understand the molecular interactions in its crystal packing, the Hirshfeld surface and contacts enrichment analyses were performed. Biological activities of the synthesized compounds were studied against gram-negative A. baumanii, E. coli, P. aeruginosa and K. pneumoniae and grampositive S. aureus bacteria.

We report the synthesis, crystal structure and Hirshfeld surface analysis of Fe(II) complex based on a pentadentate N4Py (N4Py = N,N-bis(2-pyridylmethyl)-N-(bis-2-pyridylmethyl)amine) and polynitrile tcnspr (1,1,3,3-tetracyano-2-thiopropylpropenide) ligands, [Fe(N4Py)(tcnspr)](tcnspr) 1. The X-ray result, indicates that 1 is low-spin Fe(II) complex. The tcnspr coordinated molecule in the cation exhibits disorder over two sets of atomic sites having occupancies of 0.681 (6) and 0.319 (6) and the uncoordinated tcnspr anion is also disordered over two sets of atomic sites with occupancies 0.574 (7) and 0.426 (7). The crystal packing of 1 is established mainly by weak intermolecular C–H…N/S/C hydrogen bonds and stacking interactions involving the pyridine ring and/or the C–C≡N moieties. Hirshfeld surface analysis employing three-dimensional molecular surface contours and contacts enrichment ratio calculations were used to understand the intermolecular interactions present in the structure.

International audience; A new Zn(II) complex with the guaninium monodentate ligand, [ZnCl3(C5H6N5O)], has been synthesized in aqueous solution and studied by single crystal X-ray diffraction, elemental analysis, CP-MAS-NMR and IR spectroscopy. The Zn(II) atom is coordinated in a distorted tetrahedral fashion by three chloride anions and one nitrogen atom of the guaninium cation. The compound crystallizes in the monoclinic space group P21/n with lattice parameters a = 8.8411(7), b = 11.7176(5), c = 10.3765(8) Å, β = 100.069(4) °, V = 1058.41(13) Å 3 and Z = 4. Intermolecular interactions were investigated by Hirshfeld surfaces. Besides the Zn(II) cation coordination, the crystal packing is stabilized by intermolecular N-H...O, N-H...Cland C-H...Clhydrogen bonds and C…C aromatic stacking which link the molecules into a threedimensional network. The regions of strongest negative electrostatic on the Hirshfeld surface of guaninium ligand interact with electronegative atoms and vice versa. The 13 C and 15 N CP-MAS NMR spectra are discussed and the vibrational absorption bands were identified by infrared spectroscopy. The HOMO and LUMO energies and Molecular Electrostatic Potential surface were derived from DFT theoretical calculations.

A new 1-D polymeric zinc(II) complex derived from the neutral bidentate 2-amino-4,6-dimethoxypyrimidine ligand of formula [Zn2Cl4(C6H9N3O2)2]n has been prepared and characterized by single crystal X-ray diffraction, elemental analysis and IR spectroscopy. The Zn(II) cations are tetra-coordinated, in a tetrahedral fashion, by two nitrogen atoms from the pyrimidine ring of the organic ligand and two chloride anions. In the atomic arrangement, the bridge bidentate 2-amino-4,6-dimethoxypyrimidine ligands and the tetra-connected Zn centers link each other to give a 1-D corrugated chain with molecular formula [Zn2Cl4(C6H9N3O2)2]n running along the b-axis direction. These chains, located at z = (2n+1)/4, are interconnected via C–H⋯Cl− hydrogen bonds to form layers parallel to the (a, c) plane and crossing the unit cell at y = ½. These layers are, in turn, connected to each other via C–H⋯Cl− hydrogen bonds to form a three-dimensional supramolecular network. Intermolecular interactions were investigated by Hirshfeld surfaces. The two independent organic ligands show very similar contacts and electrostatic environments. Electronic properties such as HOMO and LUMO energies were derived. The vibrational absorption bands were identified by infrared spectroscopy. This compound was also characterized by thermal analysis to determine its thermal behavior.

International audience; Highlights-31 Crystal packings of aminosalicylic acid were predicted-Predicted structure with lowest energy is close to real structure-Electrostatic properties and molecular interactions were compared Abstract The crystal structure prediction of the possible stable packings of pharmaceutical drug 4-amino-2-hydroxybenzoic acid was initiated through ab initio methods. The lattice energy values of the hypothetical conformers of the molecule generated for the global search were minimized, employing the associated distributed multipolar electron density. The crystal packing with minimum global energy corresponds to the experimental crystal. The conformer generated from the valid minimization was subjected to Quantum Theory of Atoms In Molecules (QTAIM) analysis in order to improve insight on the chemical properties of the crystal on which the pharmaceutical activity depends. The electron density and the Laplacian of the electron density were analyzed in detail for the non-covalent interactions in the crystal. While the dimer formed by the COOH/COOH homo-synthon has the strongest energy and is mostly electrostatic, other dimers formed in the crystal are mostly stabilized by dispersive forces. The complementarity of

The synthesis and the structure of (C10H15N2)4(Li)2(P6O18)(H2O)6 are described. This compound crystallizes in the triclinic system, with the centric space group P-1 and the following unit cell parameters: a = 9.7762(6), b = 10.2502(8), c = 15.2173(11) A, α = 92.588(4), β = 98.855(4), γ = 115.724(4)°, Z = 2 and V = 1346.62(17) A3. The crystal structure has been solved and refined to R = 0.0452 and Rw = 0.1121. [Li2(P6O18)(H2O)]4- entities are associated by strong O H⋯O hydrogen bonds to form inorganic layers lying in the (a, b) plane. These layers are interconnected with the organic entities via N H⋯O and C H⋯O hydrogen bonds. In this atomic arrangement, H bonds between the different species play an important role in the three-dimensional network. The contacts enrichment ratios derived from the Hirshfeld surface analysis show that the crystal packing is stabilized by ionic bridges Li+ … O, strong N/O H⋯O hydrogen bonds but also hydrophobic interactions between the two independant 1-phenylpiperazine-1,4-dium ligands. The Molecular Electrostatic Potential (MEP) maps and the HOMO and LUMO energy gaps of the new compound were computed. The title compound was further characterized by FT-IR and NMR spectroscopies. The crystal symmetry was confirmed by 31P and 7Li MAS NMR and the vibrational absorption bands were identified by infrared spectroscopy. The new compound was also characterized by thermal analysis to determine the thermal behavior.

The selectivity of L-lysine acylation by lauric acid catalysed by Candida antarctica lipase B (CALB) was investigated combining experimental and theoretical methodologies. Experiments showed the near-exclusive acylation of lysine $\epsilon$-amino group; only traces of product resulting from the acylation of lysine $\alpha$-amino group were observed fleetingly. Molecular modelling simulations were performed aiming to understand the molecular rules for selectivity. Flexible docking simulations combined with structural investigations into lysine/CALB binding modes also suggested the preferential acylation of lysine $\epsilon$-amino group without, however, excluding the acylation of the lysine $\alpha$-amino group. Electrostatic interaction energy between lysine and the residues covering the catalytic cavity was calculated in order to understand the discrimination between the two lysine amino groups. The results suggests that the proximity of the carboxylate group hinders the binding of the substrate in configurations enabling the N$\alpha$-acylation. Key interactions with the polar region covering the catalytic triad were identified and a plausible explanation for selectivity was proposed.

Errors on molecular properties including the topology of electron density and electrostatics are estimated from a sample of deviating models generated using the variance–covariance matrix issued at the end of the charge-density refinement., Estimating uncertainties of property values derived from a charge-density model is not straightforward. A methodology, based on calculation of sample standard deviations (SSD) of properties using randomly deviating charge-density models, is proposed with the MoPro software. The parameter shifts applied in the deviating models are generated in order to respect the variance–covariance matrix issued from the least-squares refinement. This ‘SSD methodology’ procedure can be applied to estimate uncertainties of any property related to a charge-density model obtained by least-squares fitting. This includes topological properties such as critical point coordinates, electron density, Laplacian and ellipticity at critical points and charges integrated over atomic basins. Errors on electrostatic potentials and interaction energies are also available now through this procedure. The method is exemplified with the charge density of compound (E)-5-phenylpent-1-enylboronic acid, refined at 0.45 Å resolution. The procedure is implemented in the freely available MoPro program dedicated to charge-density refinement and modelling.

A new Ni(II) complex with the bidentate ligand homopiperazine, [Ni(C5H12N2)2](CH3COO)2.4H2O, has been prepared and characterized by single crystal X-ray diffraction, elemental analysis and IR spectroscopy. The basic coordination patterns of the homopiperazine coordinated metal cations are slightly distorted square planar. In the atomic arrangement, the cationic complexes [Ni(C5H12N2)2]2+ are interconnected by the CH3COO−anions via N H⋯O and C H⋯O hydrogen bonds to form layers parallel to the (a, b) plane. These layers are connected by hydrogen bonds generated with water molecules to build a three dimensional network. The charge density of the compound could be refined from X-ray diffraction data measured at cryogenic temperature. Intermolecular interactions were investigated by Hirshfeld surfaces. The title compound is diamagnetic as confirmed by theoretical calculations, allowing its 13C and 15N solid-state NMR spectra to be recorded. Absorption bands were identified by infrared spectroscopy. Electronic properties such as HOMO and LUMO energies were also obtained.

International audience; A database describing the electron density of common chemical groups using combinations of real and virtual spherical atoms is proposed, as an alternative to the multipolar atom modelling of the molecular charge density. Theoretical structure factors were computed from periodic density functional theory calculations on 38 crystal structures of small molecules and the charge density was subsequently refined using a density model based on real spherical atoms and additional dummy charges on the covalent bonds and on electron lone-pair sites. The electron-density parameters of real and dummy atoms present in a similar chemical environment were averaged on all the molecules studied to build a database of transferable spherical atoms. Compared with the now-popular databases of transferable multipolar parameters, the spherical charge modelling needs fewer parameters to describe the molecular electron density and can be more easily incorporated in molecular modelling software for the computation of electrostatic properties. The construction method of the database is described. In order to analyse to what extent this modelling method can be used to derive meaningful molecular properties, it has been applied to the urea molecule and to biotin/streptavidin, a protein/ligand complex.

The Zn(II) complex with the monodentate ligand 4-fluoroaniline, ZnCl2(C6H4FNH2)2, has been prepared and characterized by single crystal X-ray diffraction, solid state nuclear magnetic resonance, infrared spectroscopy and differential scanning calorimetry. The Zn(II) ion is tetracoordinated by two nitrogen atoms of two monodentate 4-fluoroaniline ligands and two chlorine atoms. In the molecular arrangement, the ZnCl2(C6H4FNH2)2 entities are interconnected via N H⋯Cl hydrogen bonds to form layers parallel to the (a, b) plane. The nature and proportion of contacts in the crystal packing were investigated through the Hirshfeld surfaces. The crystal is mainly maintained by electrostatic attractions Cl− … H N and by extensive hydrophobic contacts as revealed by the Hirshfeld 2D fingerprint plots and statistical analysis. The13C and 19F CP-MAS NMR spectra are in agreement with the X-ray structure and confirm the phase purity of the crystalline sample. The vibrational absorption bands were identified by infrared spectroscopy. A calorimetric study shows that the title compound is stable until 262.5 °C.

Single crystals of a new organic cyclohexaphosphate (C8H12N)4(Li)2(P6O18)(H2O)6 prepared by an acid/base reaction between cyclohexaphosphoric acid H6P6O18 and 2,6-dimethylaniline, have been successfully grown by slow evaporation technique at room temperature. This compound was characterized using X-ray diffraction (XRD) and FT-IR spectroscopy. The results show that the title compound was phased with a triclinic structure and P-1 space group. The crystal structure was solved by using 5203 independent reflections with a final R value of 0.031. The P6O18 ring is centrosymmetrical. Its main geometrical features are those commonly observed in others cyclohexaphosphates. The atomic arrangement of this compound can be described by an organization in a three-dimensional framework, built up from alternated organic and inorganic species. Adjacent P6O18 rings are linked via corner-sharing by LiO4 tetrahedra, generating anionic [Li2(P6O18)(H2O)]4- layers parallel to (110). Charge balance is achieved by the protonated amine which is trapped in the interlayer space and interacts with the organic framework through strong and medium hydrogen bonding. An extensive network of N H⋯O and O H⋯O hydrogen-bonding interactions link the components into a three-dimensional network and additional stabilization is provided by weak C H⋯O hydrogen bonds. Intermolecular interactions were investigated by Hirshfeld surfaces. The vibrational absorption bands were identified by infrared spectroscopy. The stretching modes of P6O18 ring and band assignments are described.

International audience; The chemical preparation, crystal structure and spectroscopic characterization of two new Cu(II) complexes [Cu(C5H7N3O)4](CH3COO)2, [Cu(ampymo)4](O2CMe), (1) and [Cu(C5H7N3O)2(H2O)3](CH3COO)2, [Cu(ampymo)2(H2O)3](O2CMe)2, (2) with the monodentate ligand 2-amino-6-methylpyrimidin-4-(1H)-one, (ampymo), are reported. In (1), the Cu(II) atom is four-coordinated, in a square planar fashion, by nitrogen atoms of four ampymo ligands. In (2), it is five-coordinated in a square pyramidal fashion by two pyrimidine nitrogen atoms and three water oxygen atoms. The crystal structure of (1) is stabilized by N-H···O hydrogen bonds with pillars of the cationic complexes alternating with channels occupied by the acetate anions. In the atomic arrangement of (2), the complex cations are located parallel to the (a, b) plane between which the acetate anions intercalate by establishing hydrogen bonds with these cations to form a tridimensional network. The vibrational absorption bands were identified by infrared spectroscopy. Intermolecular interactions were investigated via Hirshfeld surfaces and electronic properties such as HOMO and LUMO energies were derived. 2