2-Amino-3-carb­oxy­pyridinium nitrate

In the crystal structure of the title compound, C6H7N2O2 +·NO3 −, the cations are linked via C—H⋯O hydrogen bonds, forming infinite chains running along the b axis. These chains are further linked through N—H⋯O, O—H⋯O and C—H⋯O hydrogen bonds to the nitrate anions, forming well-separated infinite planar layers parallel to (001)

Bis(3-phenylpropylammonium) dichromate (VI): Synthesis, crystal structure and spectroscopy studies

The structure of bis(3-Phenylpropylammonium) dichromate(VI) was determined from X-ray diffraction data. The compound crystallizes in the monoclinic system (space group P21/c) with the lattice parameters: a = 7.9379(2) Å, b = 36.2439(16) Å, c = 7.5753(3) Å; B = 96.069(2); V= 2167.20(14) Å3 and Z = 4. The structure was solved from 4959 independent reflections with R = 0.043 and Rw = 0.105. The structure consists of discrete dichromate anions (Cr2O72-) with eclipsed conformation stacked in layers parallel to (a, c) plane at y = 0 and ½. These anions are linked via the 3-phenylpropylammonium cations by N—H…O and C—H…O hydrogen bonds, forming a two-dimensional supramolecular network. Crystal structure and spectroscopic studies are reported for the bis(3-phenylpropylammonium) dichromate(VI)

Bis(5-amino-3-carb­oxy-1H-1,2,4-triazol-4-ium) sulfate dihydrate

The crystal structure of the title compound, 2C3H5N4O2 +·SO4 2−·2H2O, displays a three-dimensional framework in which mixed infinite chains [oriented parallel to (510) and (10)] inter­fere, forming tunnels extending parallel to the c axis. Inter­molecular O—H⋯O, N—H⋯O and O—H⋯N hydrogen bonds ensure the unity of the structure and generate centrosymmetric R 4 4(14) and R 4 2(8) rings. The S atom lies on a twofold axis

Zinc, aluminum and group 3 metal complexes of sterically demanding naphthoxy-pyridine ligands: Synthesis, structure, and use in ROP of racemic lactide and β-butyrolactone

International audienceNew potentially tridentate, bulky ortho-Ph3Si-substituted naphthol-pyridine proligands a–f were synthesized and introduced onto zinc, aluminum and group 3 metal centers (M = Sc, Y, La) using straightforward one-step alkane or amine elimination protocols. The solid-state structures of these mononuclear zinc (1a, 1c, 1d, 2c and 2e) and aluminum (3c) complexes were determined by single-crystal X-ray diffraction studies, while the solution structures were established using 1H, 13C{1H} and 29Si/29Si{1H} (when appropriate) NMR spectroscopy. For all complexes, only one species (isomer) of C1 symmetry was observed by NMR spectroscopy in the broad temperature range. Most of these complexes are effective initiators for the ring-opening polymerization (ROP) of racemic lactide (rac-LA) at 25–100 °C, affording poly(lactides)s (PLAs) generally with unimodal dispersities and molecular weights in good agreement with calculated values. An yttrium complex (4e) proved the most active (TOF = 1840 mol(LA) mol(Y)−1 h−1 at 25 °C) and yielded heterotactic-enriched PLAs (Pr up to 0.80) in toluene, while atactic PHBs were formed in the ROP of racemic β-butyrolactone (rac-BBL) under the same conditions

2-Amino-3-carb­oxy­pyrazin-1-ium perchlorate bis­(2-amino­pyrazin-1-ium-3-carboxyl­ate) monohydrate

The asymmetric unit of the title compound, C5H6N3O2 +·ClO4 −·2C5H5N3O2·H2O, comprises two symmetry-independent zwitterions, one cation, one perchlorate anion and one water mol­ecule. In the crystal, the three different types of organic entities are linked by N—H⋯O and N—H⋯N hydrogen bonds, forming undulating sheets parallel to (1-10). These sheets are in turn connected by O—H⋯N and O—H⋯O hydrogen bonds involving perchlorate anions and water mol­ecules, forming a three-dimensional network. Intra­molecular N—H⋯O and weak inter­molecular C—H⋯O hydrogen bonds are also present

2-Amino-3-carb­oxy­pyrazin-1-ium nitrate monohydrate

In crystal structure of the title compound, C5H6N3O2 +·NO3 −·H2O, inter­molecular N—H⋯O, O—H⋯N and O—H⋯O hydrogen bonds link the cations, anions and water mol­ecules into ribbons extending in [10]. Weak inter­molecular C—H⋯O hydrogen bonds further link these ribbons into sheets parallel to ( 3)

Group 3 Metal Complexes Supported by Tridentate Pyridine- and Thiophene-Linked Bis(naphtholate) Ligands: Synthesis, Structure, and Use in Stereo-selective Ring-Opening Polymerization of Racemic Lactide and beta-Butyrolactone

International audienceScandium, yttrium and lanthanum amido complexes supported by tridentate bis(ortho-silyl-substituted naphtholate)-donor ligands ({ONOSiPh3}2− and {ONOSitBuMe2}2−, donor = 2,6-pyridine; {OSOSiPh3}2−, donor = 2,5-thiophene) have been prepared in high yields (72-96%) by reaction of the corresponding pro-ligand {OZOSiR3}H2 and Ln[N(SiHMe2)2]3(THF)n precursor. The solid-state structures of {ONOSiPh3}La[N(SiHMe2)2](THF) (3), {ONOSitBuMe2}Ln[N(SiHMe2)2](THF) (Ln = Sc, 4; Y, 5) and {OSOSiPh3}Ln[N(SiHMe2)2](THF) (Ln = Sc, 7; La, 9) have been determined by single-crystal X-ray diffraction studies. In all five complexes, the naphtholate rings twist in the same direction from the plane of the pyridine or thiophene linker, to give rise to Cs-symmetric (non crystallographic) structures. Compounds 1-9 are single-site initiators for the ring-opening polymerization (ROP) of racemic lactide (rac-LA) at 20 °C, affording poly(lactides)s (PLAs) with relatively narrow polydispersities and molecular weights in good agreement with calculated values. When carried out in THF, the polymerizations afforded heterotactic-enriched PLAs (Pr up to 0.93), while atactic polymers are formed in toluene. Compounds 1-3 and 7-9, having o-SiPh3 substituents on the naphtholate rings, are also active for the ROP of racemicβ-butyrolactone at 20-50 °C, to form syndiotactic-enriched poly(3-hydroxybutyrate)s (PHBs) (Pr up to 0.87) when using toluene as the solvent, whereas atactic polymers were obtained in THF. The nature of the metal center (Sc, Y, La), the central linker in the ligand framework (pyridine, thiophene), and the ortho-silyl substituent (SiPh3, SiMe2tBu) significantly affect the degree of stereocontrol in those polymerizations

The thiocyanate anion as a polydentate halogen bond acceptor

International audienceCo-crystallisation of the Et4N+ or n-Bu4N+ salts of the thiocyanate anion with o-, m- and p-diodoperfluorobenzene or the sym-trifluorotriiodobenzene allowed for the isolation of six different salts which were structurally characterized by single crystal X-ray diffraction. Halogen bonding interactions are observed between the neutral iodinated molecules acting as halogen bond donors and the S or N ends of the thiocyanate anion, with a variety of bonding modes (terminal as well as bridging), and characterised by short I(N,S) contacts and linear C-I(N,S) motifs. On the other hand, the IN≡C angles present deviations from linearity (145-170°) while the IS-C angles are close to 90°, revealing a type II halogen bond interaction with the S atom acting as pseudo halogen. The observation of structures where only the S or the N atom are engaged in halogen bonding suggests that the two coordination modes are close in energy, as confirmed by DFT calculations and ELF analysis which give also a rationale for the observed structural preferences. This bidentate nature of the SCN− anion in halogen bonding interactions is reminiscent of its various coordination modes with the Cd2+ cation, best understood in terms of the hard-soft acid-base concept

Bis{N-[5-(4-methoxy­phen­yl)-1,3,4-oxa­diazol-2-yl]ethanimidamidato}copper(II)

The title compound, [Cu(C11H11N4O2)2], was prepared by solvothermal synthesis using 2-amino-5-(4-methoxy­phen­yl)-1,3,4-oxadiazole and copper sulfate penta­hydrate in an acetonitrile solution. The CuII atom lies on an inversion center and is four-coordinated in a slightly distorted square-planar geometry by four N atoms of the ligands obtained from the formation of a bond between the amine N atom of the oxadiazole mol­ecule and the nitrile C atom of the solvent. In the crystal structure an inter­molecular N—H⋯N hydrogen bond links inversion-related mol­ecules