Synthesis and absolute structure of (R)-2-(benzylselanyl)-1-phenylethanaminium hydrogen sulfate monohydrate: crystal structure and Hirshfeld surface analyses

A hydrogen sulfate salt, C15H18NSe+·HSO4 −·H2O or [BnSeCH2CH(Ph)NH3 +](HSO4 −), of a chiral selenated amine (R)-2-(benzylselanyl)-1-phenylethanamine (BnSeCH2CH(Ph)NH2) has been synthesized and characterized by elemental analysis,1H and 13C{1H} NMR, FT–IR analysis, and single-crystal X-ray diffraction studies. The title salt crystallizes in the monohydrate form in the non-centrosymmetric monoclinic P21 space group. The cation is somewhat W shaped with the dihedral angle between the two aromatic rings being 60.9 (4)°. The carbon atom attached to the amine nitrogen atom is chiral and in the R configuration, and, the –C—C– bond of the –CH2—CH– fragment has a staggered conformation. In the crystal structure, two HSO4 − anions and two water molecules form an R 4 4(12) tetrameric type of assembly comprised of alternating HSO4 − anions and water molecules via discrete D(2) O—H...O hydrogen bonds. This tetrameric assembly aggregates along the b-axis direction as an infinite one-dimensional tape. Adjacent tapes are interconnected via discrete D(2) N—H...O hydrogen bonds between the three amino hydrogen atoms of the cation sandwiched between the two tapes and the three HSO4 − anions of the nearest asymmetric units, resulting in a complex two-dimensional sheet along the ab plane. The pendant arrangement of the cations is stabilized by C—H...π interactions between adjacent cations running as chains down the [010] axis. Secondary Se...O [3.1474 (4) Å] interactions are also observed in the crystal structure. A Hirshfeld surface analysis, including d norm, shape-index and fingerprint plots of the cation, anion and solvent molecule, was carried out to confirm the presence of various interactions in the crystal structure.

The Amine Group as Halogen Bond Acceptor in Cocrystals of Aromatic Diamines and Perfluorinated Iodobenzenes

In order to study the proclivity of primary amine groups to act as halogen bond acceptors, three aromatic diamines (p-phenylenediamine (pphda), benzidine (bnzd) and o-tolidine (otol)) were cocrystallised with three perfluorinated iodobenzenes (1,4-tetrafluorodiiodobenzene (14tfib), 1,3-tetrafluorodiiodobenzene (13tfib) and 1,3,5-trifluorotriiodobenzene (135tfib)) as halogen bond donors. Five cocrystals were obtained: (pphda)(14tfib), (bnzd)(13tfib)2, (bnzd)(135tfib)4, (otol)(14tfib) and (otol)(135tfib)2. In spite of the variability of both stoichiometries and structures of the cocrystals, in all the prepared cocrystals the amine groups form exclusively I···N halogen bonds, while the amine hydrogen atoms participate mostly in N–H⋯F contacts. The preference of the amine nitrogen atom toward the halogen bond, as opposed to the hydrogen bond (with amine as a donor), is rationalised by means of computed hydrogen and halogen bond energies, indicating that the halogen bond energy between a simple primary amine (methylamine) and a perfluorinated iodobenzene (pentafluoroiodobenze ne) is ca. 15 kJ mol−1 higher than the energy of the (H)NH∙∙∙NH2 hydrogen bond between two amine molecules.

Pyclen-Based Ligands Bearing Pendant Picolinate Arms for Gadolinium Complexation

We report the synthesis of two pyclen-based regioisomer ligands (pyclen = 3,6,9,15-tetraazabicyclo[9.3.1]pentadeca1(15),11,13-triene) functionalized with picolinic acid pendant arms either at positions 3,9-pc2pa (L5) or 3,6-pc2pa (L6) of the macrocyclic fragment. The ligands were prepared by regiospecific protection of one of the amine nitrogen atom of the macrocycle using Boc and Alloc protecting groups, respectively. The X-ray structure of the Gd(III) complex of L5 contains trinuclear [(GdL5)3(H2O)3] 3+ entities in which the monomeric units are joined by 2- 1 : 1 carboxylate groups. However, the 1H and 89Y NMR spectra of its Y(III) analogue support the formation of monomeric complexes in solution. The Tb(III) complexes are highly luminescent, with emission quantum yields of up to 50% for [TbL5] + . The luminescence lifetimes recorded in H2O and D2O solutions indicate the presence of a water molecule coordinated to the metal ion, as also evidenced by the 1H relaxivities measured for the Gd(III) analogues. The Gd(III) complexes present very different exchange rates of the coordinated water molecule (kex 298 = 87.1 and 1.06 106 s -1 for [GdL5] + and [GdL6] + , respectively). The very high water exchange rate of [GdL5] + is associated to the steric hindrance originated by the coordination of the ligand around the water binding site, which favors a dissociatively activated water exchange process. The Gd(III) complexes present rather high thermodynamic stabilities (logKGdL = 20.47 and 19.77 for [GdL5] + and [GdL6] + , respectively). Furthermore, these complexes are remarkably inert with respect to their acid-assisted dissociation, in particular the complex of L5.

Pyclen-Based Ligands Bearing Pendant Picolinate Arms for Gadolinium Complexation

We report the synthesis of two pyclen-based regioisomer ligands (pyclen = 3,6,9,15-tetraazabicyclo[9.3.1]pentadeca1(15),11,13-triene) functionalized with picolinic acid pendant arms either at positions 3,9-pc2pa (L5) or 3,6-pc2pa (L6) of the macrocyclic fragment. The ligands were prepared by regiospecific protection of one of the amine nitrogen atom of the macrocycle using Boc and Alloc protecting groups, respectively. The X-ray structure of the Gd(III) complex of L5 contains trinuclear [(GdL5)3(H2O)3] 3+ entities in which the monomeric units are joined by 2- 1 : 1 carboxylate groups. However, the 1H and 89Y NMR spectra of its Y(III) analogue support the formation of monomeric complexes in solution. The Tb(III) complexes are highly luminescent, with emission quantum yields of up to 50% for [TbL5] + . The luminescence lifetimes recorded in H2O and D2O solutions indicate the presence of a water molecule coordinated to the metal ion, as also evidenced by the 1H relaxivities measured for the Gd(III) analogues. The Gd(III) complexes present very different exchange rates of the coordinated water molecule (kex 298 = 87.1 and 1.06 106 s -1 for [GdL5] + and [GdL6] + , respectively). The very high water exchange rate of [GdL5] + is associated to the steric hindrance originated by the coordination of the ligand around the water binding site, which favors a dissociatively activated water exchange process. The Gd(III) complexes present rather high thermodynamic stabilities (logKGdL = 20.47 and 19.77 for [GdL5] + and [GdL6] + , respectively). Furthermore, these complexes are remarkably inert with respect to their acid-assisted dissociation, in particular the complex of L5.

Pyridine-4-carboxamidoxime N-oxide

Our work in the area of synthesis of metal–organic frameworks (MOFs) based on organic N-oxides led to the crystallization of pyridine-4-carboxamidoxime N-oxide. Herein we report the first crystal structure of the title compound, C6H7N3O2 [systematic name: (Z)-4-(N′-hydroxycarbamimidoyl)pyridine N-oxide]. The hydroxycarbamimidoyl group is essentially coplanar with the aromatic ring, r.m.s.d. = 0.112 Å. The compound crystallizes in hydrogen-bonding layers built from the formation of strong O—H...O hydrogen bonds between the oxime oxygen atom and the oxygen atom of the N-oxide, and the formation of N—H...O hydrogen bonds between one amine nitrogen atom and the N-oxide oxygen atom. These combined build R 3 4(24) ring motifs in the crystal. The crystal structure has no π–π interactions.

Platinum(II) complexes of pyridine–amine ligands with phenol substituents: isotactic supramolecular polymers

The platinum(II) complexes [PtCl(SMe2)(κ2-N,N′-L)]Cl and [PtMe(SMe2)(κ2-N,N′-L)]Cl, L = 2-C5H4NCH2NH-x-C6H4OH (x = 2, 3, or 4), have been prepared and structurally characterized. In all cases, the complexes form supramolecular polymers in the solid state by NH··Cl and OH··Cl hydrogen bonding to the chloride anion. The ligands are chiral at the amine nitrogen atom, and in all cases, the polymers are isotactic, formed by self-recognition or narcissistic self-assembly. The structures in the crystalline state all have the Me2S ligand trans to pyridyl, but in solution, the methylplatinum(II) complexes isomerise slowly to give an equilibrium with the isomers having the methyl group trans to the pyridyl donor.

N-Tris[(2-aminoethyl)-2-(diphenylphosphoryl) acetamide)] — novel CMPO tripodand: synthesis, extraction studies and luminescent properties of lanthanide complexes

A ligand system containing three carbamoylmethylphosphine oxide (CMPO) moieties attached to a tripodal platform with a central nitrogen atom has been synthesized for metal complexation and extraction from neutral and nitric acid solutions. Liquid-liquid extractions performed for Ln(III), both from neutral and acidic media, show excellent extraction properties which exceeded those for the known mono- and di-CMPO derivatives as well as the related tripodands. A considerable enhancement of the DLn values was observed in the presence of IL ([bmim][Tf2N]) in the organic phase towards lanthanide ions from 3M HNO3 solutions. The protonation of the central amine nitrogen atom of the ligand 1 in the acidic media provides also the effective extraction of the perrhenate anionic complexes. The europium complexes formed by mono- and tris-CMPO ligands in the solid state, as well as Eu(III) and Tb(III) complexes generated in solutions, possess intensive luminescence at 300K

Synthesis and Characterization of New Palladium(II) Complexes Containing N-Alkylamino-3,5-diphenylpyrazole Ligands. Crystal Structure of [PdCl(L2)](BF4) {L2 = Bis[2-(3,5-diphenyl-1-pyrazolyl)ethyl]ethylamine}

In this paper, the synthesis of two new N,N′,N-ligands, bis[2-(3,5-diphenyl-1-pyrazolyl)ethyl]amine (L1) and bis[2-(3,5-diphenyl-1-pyrazolyl)ethyl]ethylamine (L2) is reported. These ligands form complexes with the formula [PdCl(N,N′,N)]Cl when reacting with [PdCl2(CH3CN)2] in a 1:1 metal-to-ligand molar ratio. Treatment of these ligands with [PdCl2(CH3CN)2] in a 1:1 metal-to-ligand molar ratio in the presence of AgBF4 or NaBF4 gave [PdCl(N,N′,N)](BF4) complexes. These PdII complexes were characterized by elemental analyses, conductivity measurements, mass spectrometry, and IR, 1H, and 13C{1H} NMR spectroscopies. The X-ray structure of the complex [PdCl(L2)](BF4) has been determined. The metal atom is coordinated by two azine nitrogen atoms and one amine nitrogen atom of the aminopyrazole ligand. The distorted square planar coordination is completed by one chlorine atom. In this complex, intermolecular π–π stacking interactions are present.