Search results for "MR"

1H NMR study of dynamical inequivalence of cations in [C(NH2)3]3Sb2Cl9

2001

Abstract The proton NMR second moment and spin–lattice relaxation time have been studied for polycrystalline tris-guanidinium nonachlorodiantimonate(III) in a wide temperature range. The C 3 reorientation of two types of the cations, hindered by very different potential barriers (20.5 and 54.5 kJ/mol) has been revealed. An unusually large dynamical inequivalence of two cations evidently reflects their different crystalline environments.

15N NMR studies of tautomerism

2012

The literature related to 15N NMR studies of tautomerism is updated and discussed. The 15N NMR data show that the technique is applicable for both liquid and solid state (both crystalline and amorphous) materials. Modern computational methods combined with experimental NMR data can aid in the chemical shift assignments especially in case of crystalline materials (so-called NMR crystallography). This review article is divided into chapters based on the different classes of compounds and a brief description of experimental and computational NMR techniques is also included.

ChemInform Abstract: Asymmetrically Substituted Calix(4)arenes. A Two-Dimensional 1H NMR Study of a Tetraester Derivative in the cone-Conformation.

2010

1977

Solutions of chain- (PS-d3) and phenyl ring (PS-d5) deuterated polystyrenes in perdeuterated PS-d8 have been investigated with 1H and 2D NMR relaxation and wide line methods. The intra- and intermolecular parts of the 1H second moments at −100°C are 3,7 G2 and 2,0 G2, respectively, for PS-d3, and 14,7 G2 and ca. 0 G2, respectively, for PS-d5. The intermolecular contribution to the 1H spin lattice relaxation rate, determined at 55 MHz between 150°C and 250°C, is about one third of the total rate in PS-d3, and negligible in PS-d5. We suggest that this contribution is caused by rotational fluctuations of the intermolecular H H vectors. The intramolecular 1H- and 2D-relaxation rates indicate th…

Caratterizzazione NMR ed EPR di mattoni del Teatro Antico di Taormina.

2010

Preparation and structural studies on diorganotin(IV) complexes of N-nitroso-N-phenylhydroxylaminates

2007

Abstract Diorganotin(IV)-complexes of the N -nitroso- N -phenylhydroxylaminates (hereinafter cupf), Et 2 Sn(cupf) 2 ( 1 ), Bu 2 Sn(cupf) 2 ( 2 ), {[Bu 2 Sn(cupf)] 2 O} 2 ( 3 ), t -Bu 2 Sn(cupf) 2 ( 4 ) and Oc 2 Sn(cupf) 2 ( 5 , 6 ) were prepared and characterised by FT-IR and Mossbauer spectroscopic measurements. The binding modes of the ligand were identified by FT-IR spectroscopy, and it was found that the ligand is coordinated in chelating or bridging mode to the organotin(IV) center. The 119 Sn Mossbauer and FT-IR studies support the formation of trans -O h ( 1 – 6 ) structures. The X-ray diffraction analysis of 4 revealed that the tin centre is in a skew-trapezoidal geometry defined by…

On/Off Photoswitching in a Cyanide-Bridged {Fe2Co2} Magnetic Molecular Square

2013

International audience; A repeatable bidirectional paramagnetic ↔ diamagnetic photomagnetic effect has been observed in the cyanide-bridged Fe-Co square complex {[Fe{B(pz)(4)}(CN)(3)](2)[Co(bik)(2)](2)}(ClO(4))(2)*3H(2)O [B(pz)(4) = tetrapyrazolylborate, bik = bis(1-methylimidazol-2-yl)ketone]. Magnetic measurements and low-temperature single-crystal X-ray diffraction experiments have shown that a complete electron transfer from the diamagnetic Fe(II)-Co(III) state to the paramagnetic Fe(III)-Co(II) metastable state is induced by 808 nm laser light irradiation, whereas the diamagnetic state is recovered in an almost quantitative yield under irradiation at 532 nm.

Cyanide-bridged Fe(III)–Co(II) bis double zigzag chains with a slow relaxation of the magnetisation

2003

Reaction of [FeIII(bipy)(CN)4]¯ with fully solvated MII cations [M = Co (1) and Mn (2)] produces the isostructural bis double zigzag chains [[FeIII(bipy)(CN)4]2MII(H2O)]·MeCN·1/2H2O; 1 exhibits intrachain ferromagnetic and interchain antiferromagnetic couplings, slow magnetic relaxation and hysteresis effects. Luminita Marilena, Toma, Luminita.Toma@uv.es ; Lescouezec, Alain Francois Rodri, Alain.Lescouezec@uv.es ; Lloret Pastor, Francisco, Francisco.Lloret@uv.es ; Julve Olcina, Miguel, Miguel.Julve@uv.es

Phosphorus NMR as a tool to study mineralization of organophosphonates—The ability of Spirulina spp. to degrade glyphosate

2007

Abstract A commercially available mixed culture of Spirulina spp. exhibited a remarkable ability to degrade the widely used organophosphorus herbicide glyphosate, that served as sole source of either phosphorus or nitrogen for cyanobacterial growth. 31P NMR analysis of spent media appeared to be an effective and simple technique to follow disappearance of the phosphonate and release of inorganic phosphate in biodegradation process(es).

Synthesis, spectroscopic, cyclic voltammetry properties and molecular structure of the thiocyanato-N meso-tetratolylporphyrinato zinc(II) ion complex

2017

International audience; This paper describes the synthesis of the (thiocyanato-N)(meso-tetratolylporphyrinato)zinc(II) chlorobenzene monosolvate complex with the formula [K(2,2,2-crypt)][Zn(TTP)(NCS)]·C6H5Cl (I) using the cryptand-222 to solubilize potassium thiocyanate in chlorobenzene solvent. Complex (I) has been characterized by elementary analysis, IR, UV–vis, 1H NMR and MS, and the structure of this new zinc(II) metalloporphyrin been examined crystallographically. A cyclic voltammetry investigation was also carried out on this species. The title compound crystallizes in the triclinic, space group P-1, with a = 11.5151(7) Å, b = 15.212(10) Å, c = 20.1093(12) Å, α = 80.428(4)°, β = 74.9…