Multiple light-induced NO linkage isomers in the dinitrosyl complex [RuCl(NO)₂(PPh₃)₂]BF₄ nravelled by photocrystallographic and IR analysis

Multiple light-induced reversible metastable NO linkage isomers (PLIs) have been detected in the dinitrosyl compound [RuCl(NO)(2)(PPh3)(2)]BF4 by a combination of photocrystallographic and IR analysis. The IR signature of three PLI states has been clearly identified, with estimated populations of 59% (PLI-1), 8% (PLI-2) and 5% (PLI-3) for a total population of the metastable state of 72%. The structural configuration of the major component (PLI-1) has been derived by X-ray photocrystallography. In the ground state, the structure is characterized by a bent and a linear nitrosyl, the bent one being oriented towards the linear equatorial nitrosyl with an Ru-N-O angle of 133.88 (9)degrees. X-ray Fourier difference maps indicate a selectivity of the photo-isomerization process in PLI-1: only the bent NO ligand changes its position, while the linear NO is unaffected. After irradiation at 405 nm, the orientation is changed by rotation towards the Cl ligand opposite the linear NO, with an Ru-N-O angle in this new position of 109 (1)degrees. The photocrystallographic analysis provides evidence that, in the photo-induced metastable state, the bent NO group is attached to the Ru atom through the N atom (Ru-N-O),rather than in an isonitrosyl Ru-O-N binding mode. In the IR spectra, the asymmetric NO vibrational band shifts by -33 cm(-1) to a lower value, whereas the symmetric band splits and shifts by 5 cm(-1) to a higher value and by -8 cm(-1) to a lower value. The down shift is a clear indication of the structural change, and the small upward shift in response to the new electronic configuration of the metastable structure. Variable-temperature IR kinetic measurements in the range 80-114 K show that the decay of the PLI-1 state follows an Arrhenius behaviour with an activation energy of 0.22 eV

1-[3-(4-Nitro­phen­yl)propano­yl]urea acetic acid monosolvate

The title compound, C10H11N3O4·C2H4O2, was prepared by an electrochemical technique. In the crystal, acetic acid mol­ecules are involved in hydrogen bonding to two separate propano­ylurea mol­ecules, acting as a donor in an O—H⋯O inter­action and as an acceptor in two N—H⋯O inter­actions. The propano­ylurea mol­ecules inter­act with each other via N—H⋯O hydrogen bonds. C—H⋯O inter­actions also stabilize the crystal structure

Correlation between structural studies and third order NLO properties of selected new quinolinium semi-organic compounds

New quinolinium semi-organic compounds of formula ( C 9 H 8 N ) 2 + · SO 4 2 - , H 2 O (I) (bis-quinolinium sulphate monohydrate) and ( C 9 H 8 N ) + · NO 3 - (II) (quinolinium nitrate) have been synthesized and characterized by UV–Vis absorption spectroscopy, nonlinear optical (NLO) measurements and by single crystal X-ray diffraction. The third order nonlinear optical properties of (I) and (II) were investigated using two methods: the degenerate four wave mixing technique (DFWM) performed in solution at λ = 532 nm and the third-harmonic generation (THG) measurements carried out on thin films at λ = 1064 nm. The NLO measurements showed that compound (I) presents better nonlinear optical properties compared to compound (II). To understand further the optical behaviour of (I) and (II), the crystal structures of both compounds were determined from accurate single crystal X-ray diffraction measurements performed at 100 K. The crystallographic studies revealed the key role of the intermolecular interactions and the molecular arrangements in the enhancement of the NLO properties

Characterization of multifunctional β-NaEuF4/NaGdF4 core–shell nanoparticles with narrow size distribution

We characterized NaEuF4/NaGdF4 core–shell nanoparticles

Conducting Anilate-Based Mixed-Valence Fe(II)Fe(III) Coordination Polymer: Small-polaron Hopping Model for Oxalate-Type Fe(II)Fe(III) 2D Networks

The mixed-valence FeIIFeIII 2D coordination polymer formulated as [TAG][FeIIFeIII(ClCNAn)3]·(solvate) 1 (TAG = tris(amino)-guanidinium, ClCNAn2− = chlorocyanoanilate dianionic ligand) crystallized in the polar trigonal space group P3. In the solid-state structure, determined both at 150 and at 10 K, anionic 2D honeycomb layers [FeIIFeIII(ClCNAn)3]− establish in the ab plane, with an intralayer metal−metal distance of 7.860 Å, alternating with cationic layers of TAG. The similar Fe−O distances suggest electron delocalization and an average oxidation state of +2.5 for each Fe center. The cation imposes its C3 symmetry to the structure and engages in intermolecular N−H···Cl hydrogen bonding with the ligand. Magnetic susceptibility characterization indicates magnetic ordering below 4 K and the presence of a hysteresis loop at 2 K with a coercive field of 60 Oe. Mössbauer measurements are in agreement with the existence of Fe(+2.5) ions at RT and statistic charge localization at 10 K. The compound shows semiconducting behavior with the in-plane conductivity of 2 × 10−3 S/cm, 3 orders of magnitude higher than the perpendicular one. A small-polaron hopping model has been applied to a series of oxalate-type FeIIFeIII 2D coordination polymers, providing a clear explanation on the much higher conductivity of the anilate-based systems than the oxalate ones

Cristallographie à haute résolution des complexes acides minéraux bases azotées ou acides aminés : Etude des interactions intermoléculaires

Organic-inorganic hybrid materials resulting from the association of amino acids with phosphorous acid have a great importance in industry: IR, very high SGH, and NLO properties make these hybrid materials highly attractive for frequency doubling, they also can be used as infrared detectors and pyroelectric devices). We report in the first part of this work chemical preparation, infrared and NMR spectroscopic studies and structural determination by single crystal X-ray diffraction of six new hybrid complexes. The second part is devoted to an accurate analysis of the reversible first order single crystal phase transition that occurs in m-CPAMP. The thermal behaviour and the study of charge density of m-CPAMP using high-resolution data sets collected with synchrotron and neutron diffraction experiments at low temperature will be presented and discussed. This study allows a better understanding of the phase transition mechanism.Les matériaux hybrides "organique-inorganique" sont l'objet d'un intérêt immense, en permettant d'allier à la fois certaines propriétés d'un matériau inorganique (ou d'une molécule), et certaines propriétés d'un polymère (ou d'une molécule organique). Les applications de ces matériaux "nouveaux" couvrent des champs aussi variés que les propriétés de résistance mécanique, l'optique, l'électronique et l'ionique du solide et les biomatériaux. Notre étude porte sur les complexes hybrides constitués de groupements phosphite (ou phosphate) comme anions minéraux et d acides aminés ou de bases azotées comme matrices organiques. La première partie de ce travail est consacrée à la caractérisation spectroscopique ainsi que l étude structurale de six nouveaux composés hybrides à base de phosphate et de phosphite. Nous présentons dans la deuxième partie une étude très détaillée de la transition de phase réversible de premier ordre avec effet d hystérésis présente dans le composé m-CPMAP. La discussion du comportement des divers groupements autour de la transition est suivie par une analyse haute résolution de la densité électronique dans la phase basse température à partir de données synchrotron, combinée à une analyse neutronique