A new copper(II) coordination compound with 2,2′-bipyridine-N-oxide as a ligand: Crystal structure, synthesis and spectroscopy

A new copper(II) coordination compound with the ligand 2,2′-bipyridine-N-oxide (abbreviated as bpyNO), Cu(bpyNO)₂(CF₃SO₃)₂, is described. This compound is investigated in detail by spectroscopy, EPR and X-ray crystal structure analysis. The compound crystallizes in the monoclinic space group P2₁/n with a = 6.554(1) ?, b = 13.681(3) ?, c = 14.935(3) ?, β = 98.77(3)°, Z = 2. The copper has an axial elongated octahedral geometry with the basal plane formed by two trans-orientated bpyNO molecules with Cu_N distance of 2.008(2) ? and a Cu_O distance of 1.950(2) ?. The axial positions are occupied by oxygen atoms of two trans-oriented triflate anions with a Cu_O distance of 2.397(2) ?.     

Mass spectra of chlorinated aromatics formed in pulp bleaching: I—chlorinated catechols

A systematic study on the electron impact mass spectra of all nine chlorinated catechols in presented. Metastable ion analysis was used to elucidate the fragmentation pathways. The influence of the position of the chloro substituents can be used to distinguish the structural isomers. In this respect the most characteristic fragment ions are [M? CHl]⁺˙, [M? HCOOH]⁺˙, [M? COCl]⁺, [M? HCl? CO]⁺˙, [M? CHOCl]⁺˙ and [M? HCl? HCl]⁺˙.     

The self-assembly between C2-symmetric (methanol)6 or S6-symmetric (ethanol)6 cyclohexamers and paddle-wheel dinuclear copper units leads to unique 1D polymer chains

The first crystallographic evidences of the theoretically suggested C2-symmetric cyclohexameric form of liquid methanol and the S6-symmetric cyclohexameric form of liquid ethanol are reported, trapped inside a hydrophilic pocket shielded by tert-butyl groups.     

Versatility in the binding of 2-pyrazinecarboxylate with iron. Synthesis, structure and magnetic properties of iron(II) and iron(III) complexes

The synthesis and characterization of two new iron(II) complexes, [Fe(pca)2(py)2].py (1) and {[Fe(pca)2(H2O)].H2O}n (2) and one new iron(III) complex, Na2{[Fe(pca)()]2O}.2H2O.2CH3CN (3) (pca- stands for 2-pyrazinecarboxylate), are reported. Complex 1 is obtained from the reaction of iron powder with 2-pyrazinecarboxylic acid. The reaction of Fe(ClO4)3.10H2O with Hpca in the presence of 3 equiv. of Bu4NOH yields 2, whereas the presence of NaOH yields 3. The molecular structure of 1 contains an iron(II) ion with a pseudo-octahedral environment resulting from the coordination of two pca- ligands in a bidentate chelating fashion and two pyridine molecules; pi-pi stacking interactions between pyridine and pyrazine rings lead to a one-dimensional chain. Complex 2 is an iron(II) coordination polymer with an infinite zig-zag motif and an Fe...Fe separation of 7.1 A. In 2, the pi-pi stacking interactions involving the pyrazine rings and the strong hydrogen bonds between the coordinated water molecule and the carboxylate oxygens of two pca- ligands result in a three-dimensional network structure. Complex 3 consists of an anionic micro-oxo-bridged diiron(III) core with two crystallographically distinct iron(iii) ions; the negative charge is compensated by two sodium cations. Complex 3 is assembled in a three dimensional network structure through coordination of Na(I) and hydrogen bond interactions. Temperature dependent magnetic susceptibility and M?ssbauer spectroscopic studies indicate that 1 and 2 have similar magnetic properties. Both complexes are paramagnetic above 12 K, whereas antiferromagnetic ordering is observed below 12 K. The magnetic properties of reveal strong intramolecular antiferromagnetic interactions between the two iron(III) ions with a J value of -221 cm(-1); no long range intermolecular magnetic coupling is observed between 295 and 4.2 K.     

Synthesis, crystal structure, hydrogen bonding and spectroscopy of transition-metal complexes with the ligand (N,N′-bis(2-pyridylmethyl)-1,3-propanediamine)

Six mononuclear complexes are reported with the tetradentate ligand N,N′-bis(2-pyridylmethyl)-1,3-propanediamine, (abbreviated as pypn) i.e. [Cu(pypn)(ClO₄)₂](H₂O)_1/2 (1), [Fe(pypn)Cl₂](NO₃) (2), [Zn(pypn)Cl](ClO₄) (3), [Co(pypn)(NCS)₂](ClO₄) (4), [Co(pypn)(N₃)₂](ClO₄) (5), [Zn(pypn)(NCS)₂] (6). The synthesis and X-ray crystal structures of all six compounds and their spectroscopic properties are presented.The geometry of the Cu²⁺, Co³⁺, Zn²⁺, Fe³⁺ ions is essentially octahedrally based, with the mm conformation (for Cu) and m_sf conformations for the other 3 metal ions; in compound 3 the geometry around the Zn²⁺ is distorted trigonal bipyramidal. The stabilisation of the crystal lattices is maintained by interesting, relative strong hydrogen bonds.     

Two Mononuclear Compounds with bis(Pyrimidin-2-yl)amine as a Ligand and as a Hydrogen-bonded Lattice Molecule. Synthesis, Structure and Spectroscopy of {[M(dipm)(H2O)(A)](dipm)(A)(H2O)} (M?=?Cd with A?=?ClO4; and Zn with A?=?BF4)

Abstract  Two isostructural mononuclear compounds with formula {[Cd(dipm)(H₂O)(ClO₄)](dipm)(ClO₄)(H₂O)} (1) {[Zn(dipm)(H₂O)(BF₄)](dipm)(BF₄)(H₂O)} (2) and (in which dipm = bis(pyrimidin-2-yl)amine) have been synthesised and characterised by X-ray crystallography and infrared spectroscopy. The structure of compound 1 has been solved in the space group P2₁/n with a = 18.860(4), b = 8.579(2), c = 20.917(4) ?, β = 101.33(3)°, V = 3318.4(12) ?³, Z = 4 with final R = 0.0454. The structure of compound 2 has also been solved in the space group P2₁/n with a = 19.026(4), b = 8.389(1), c = 20.720(4) ?, β = 101.37(3)°, V = 3242.2(10) ?³, Z = 4 with final R = 0.0689. The geometry around the metal ions is octahedral, and is constituted by four nitrogen atoms from two dipm molecules, an oxygen atom from a water molecule and a semi-coordinating anion atom ( for compound 1 and for compound 2). In the lattice are also present: a non-coordinating water molecule, an anion molecule and a dipm molecule. For compound 1, the Cd–N distances are between 2.296 and 2.328 ?. The distance is 2.310 ? and the is 2.477 ?. The Zn–N distances in compound 2 are between 2.121 and 2.164 ?. The distance is 2.147 ? and the distance is 2.373 ?. A hydrogen bond interaction of the Watson–Crick type is observed between the amine N atom of a dipm ligand to a pyrimidyl N atom and a non-coordinating dipm ligand with N···N distances, which vary from 3.066(5) to 3.109(5) ?. Furthermore medium to strong hydrogen bond interactions are present between oxygen atoms of the water molecules and the anions of the compounds. Index Abstract  Two isostructural mononuclear compounds with formula {[Cd(dipm)(H₂O)(ClO₄)](dipm)(ClO₄)(H₂O)} (1) {[Zn(dipm)(H₂O)(BF₄)](dipm)(BF₄)(H₂O)} (2) and (in which dipm = bis(pyrimidin-2-yl)amine) have been synthesised and characterised by X-ray crystallography and infrared spectroscopy. . Electronic supplementary material  The online version of this article (doi:) contains supplementary material, which is available to authorized users.     

Two Different Compounds Formed from Copper(II) tetrafluoridoborate and [1,2,4]triazolo[1,5-a]pyrimidine. Synthesis,Spectroscopy and Single-Crystal Structures

Abstract  

Two coordination compounds copper(II) with tetrafluoridoborate as the anion and [1,2,4]triazolo[1,5-a]pyrimidine (abbreviated as tp) as the ligand are presented, together with their crystal structure and spectroscopic properties. A light blue compound [Cu(tp)₄(H₂O)₂](BF₄)₂(CH₃OH) (1) with a tetragonal chromophore and a dark blue compound [Cu(tp)₅](BF₄)₂(CH₃OH) (2) are formed from the same batch. Compound (2) has a quite unusual geometry for Cu(II) with just 5 tp ligands, homoleptically coordinated to the metal ion. Both compounds show interesting hydrogen-bond interactions in the solid state, where coordinated water is intramolecularly bound to non-coordinated N atoms of tp (in 1), and methanol is attached to the anion (in 2).     

Red and Blue Compounds Formed from Copper(II) Bromide and the Ligand 7-Isobutyl-5-methyl-[1,2,4]triazolo[1,5-a]pyrimidine: Synthesis, Spectroscopy and Single-Crystal Structures

Abstract  

Two newly synthesized coordination compounds copper(II) bromide with the ligand 7-isobutyl-5-methyl[1,2,4]triazolo[1,5-a]pyrimidine (abbreviated as ibmtp) are presented, together with their 3D crystal structure and spectroscopic and magnetic properties. The compounds are CuBr₂(ibmtp)₂ (1) (red crystals) and [CuBr(ibmtp)₄]Br(H₂O)₃ (2) (blue crystals). In (1) the Cu(ii) ion is present in a distorted tetrahedral environment, while in (2) the Cu(ii) ion has a square pyramidal geometry. These crystal structures are also the first ones reported with the ligand ibmtp.     

Transient ordered domains in single-component phospholipid bilayers

We report evidence of dense, ordered nanodomains in single-component fluid lipid bilayers. Our atomic-scale molecular dynamics simulations suggest that the area available to a lipid acyl chain exhibits large fluctuations, resulting in denser and sparser domains. The sizes of the dense domains can be up to approximately 10 nm, and their lifetimes are of the order of approximately 10 ns. In addition, our simulations suggest that domains of lipids with highly ordered acyl chains form predominantly within the dense regions, their sizes ranging from a few chains up to a few nanometers, and with lifetimes between approximately 10 ps-10 ns. These observations shed light on the origin of experimentally observed fluctuations, as well as on the mechanisms of phase transitions in lipid membranes.