Search results for "molecule"

Synthesis, Crystal Structure and Magneto‐Structural Correlation of an Unusual Thiocyanato‐Bridged Nickel( II ) Compound, [Ni(μ‐NCS)(dpt)(NCS)] 2 [Ni(…

2003

Reaction of Ni(ClO4)2·6H2O with bis(3-aminopropyl)amine (dpt) and ammonium thiocyanate produces the novel thiocyanato-bridged nickel(II) compound [Ni(μ-NCS)(dpt)(NCS)]2[Ni(μ-NCS)(dpt)(NCS)]4, which has been structurally characterised. The structure determination reveals that there are two different molecules in the crystal lattice; one is dinuclear and other is tetranuclear. Low-temperature magnetic measurements show that there are ferro- as well as antiferromagnetic interactions. The ferromagnetic interaction arises from the dinuclear part and the doubly bridged part of the tetranuclear unit; the antiferromagnetic interaction occurs between singly bridged nickel centres in the tetranuclear…

Rhenium(IV) cyanate complexes: Synthesis, crystal structures and magnetic properties of NBu4[ReBr4(OCN)(DMF)] and (NBu4)2[ReBr(OCN)2(NCO)3]

2006

Abstract Two new rhenium(IV) mononuclear compounds of formula NBu4[ReBr4(OCN)(DMF)] (1) and (NBu4)2[ReBr(OCN)2(NCO)3] (2) (NBu4 = tetrabutylammonium cation, OCN = O-bonded cyanate anion, NCO = N-bonded cyanate anion and DMF = N,N-dimethylformamide) have been synthesized and their crystal structures determined by single-crystal X-ray diffraction. 1 crystallizes in the monoclinic system with the space group P21/n, whereas 2 crystallizes in the triclinic one with P 1 ¯ as space group. In both complexes the rhenium atom is six-coordinated, in 1 by four Br atoms in the equatorial plane, and two trans-oxygen atoms, one of a DMF molecule and another one from a cyanato group, while in 2 by one brom…

High-Temperature Ammonolysis of Uranium Trichloride and Tetrachloride

1965

Mössbauer spectroscopic studies on compounds containing tin-cadmium and tin-zinc bonds

1975

The Mossbauer parameters of compounds Ph3Sn MCl · TMED (M = Cd, Zn; TMED = N,N,N′,N′-tetramethylethylenediamine), (Ph3Sn)2CdL2 (L2 = TMED, 2,2′-bipyridine and o-phenanthroline) and (Ph3Sn)2 Zn · TMED have been determined and are discussed in connection with Mossbauer data concerning Ph3SnIV derivatives with other Sn-metal bonds. The isomer shift values suggest a high s character in SnCd and SnZn bonds resulting in deviations from regular tetrahedral environments around tin. Experimental quadrupole splittings and calculated partial quadrupole splitting values indicate reduced donor abilities towards the tin atom of an individual Ph3SnIV moiety by Cd-and Zn(Ph3Sn)1−nClnL2 (i.e., the remaini…

Why Do Chemically Similar Pharmaceutical Molecules Crystallize in Different Structures: A Case of Droperidol and Benperidol

2016

A detailed study of molecular conformation and intermolecular interactions in the experimental crystal structures and general trends observed in the Cambridge Structural Database as well as theoretical calculations were performed to identify the reason for the formation of different crystal structures of two chemically very similar pharmaceutical molecules benperidol and droperidol. The most important difference between both molecules was the weak intermolecular interactions formed by the central ring which therefore was responsible for the formation of different crystal structures. Cross-seeding experiments were performed to check the possibility for the formation of mutually isostructural…

MCSCF determination of the KO molecule ground state.

1992

Abstract Ab initio calculations at the MC/CASSCF level are used to determine in an accurate way the nature and position of the ground state of the KO molecule. The characteristic 2 Π and 2 Σ + alkali monoxide ionic states show a theoretical energy separation of about 0.04 eV, which produces opposite results by authors in favour of one or the other symmetry. We test the basis set dependence and active space dependence of the calculated energetical ordering of both states, with an extensive study of the active orbitais selection; the results show a ground state of 2 Σ + symmetry.

Electrodes for REMPI spectroscopy in static gases and calculation of REMPI intensities: Application to molecular oxygen

1994

Resonance-enhanced multiphoton ionization (REMPI) of 16 O 2 X 3 Σ g − (ν = 0) through (3sσ g ) d'Π g (ν = 0) by using (2 + 1) one-colour photons is reported. This REMPI process, already observed and analysed by other authors at low pressure and low rotational temperature with mass spectrometry detection, is used to test our first detector of ionizations. Experimental difficulties have led to the design of an original arrangement of electrodes to collect electrons at room temperature and 1 Torr pressure of static molecular oxygen. A calculated spectrum is compared with the observed REMPI spectrum. The calculation uses the polarizability tensor and takes into account the competition between i…

Vibrational effects in Na2( , v′)+Na(3p3/2) associative ionization

1999

Abstract Associative ionizing Na2( A 1 Σ + u , v′)+Na(3p3/2) collisions have been studied in a single supersonic beam with respect to the influence of the initial vibrational excitation of the molecules on the reaction efficiency. An enhancement of trimer ion yield of nearly one order of magnitude has been observed as the vibrational excitation increases from v′=0 to v′=14.

{[Hg(SCN)3]2(n-L)}2-: An Efficient Secondary Building Unit for the Synthesis of 2D Iron(II) Spin-Crossover Coordination Polymers

2018

[EN] We report an unprecedented series of two-dimensional (2D) spin-crossover (SCO) heterobimetallic coordination polymers generically formulated as {Fe-II[(He(SCN)(3))(2)](L)(x))}center dot Solv, where x = 2 for L = tvp (trans-(4,4'-vinylenedipyridine)) (1tvp), bpmh ((1E,2E)-1,2-bis(pyridin-4-ylmethylene)hydrazine) (1bpmh center dot nCH(3)OH; n = 0, 1), by eh ( (1E,2E)-1,2-bis (1-(pyridin-4-yl) ethyliden e) hydrazine) (Ibpeh center dot nH(2)O; n = 0, 1) and x = 2.33 for L = 0 0 bpbz (1,4-bis(pyridin-4-yl)benzene) (1bpbz center dot nH(2)O; n = 0, 2/ 3). The results confirm that self-assembly of Fell, [Hg-II(SCN)(4)](2-), and ditopic rodlike bridging ligands L containing 4-pyridyl moieties f…

Hypervalent tin-organic compounds: Vibrational spectroscopy in the solid as a tool for structure determination

1997

Abstract A full set of IR- and Raman spectra down from 600 cm1 has been determined and assigned for 60 penta- or hexacoordinated tin-compounds in the groups RSn(CH2CH2CH2)3N (R = Cl, Br, I, Me), RR'Sn(MCH2CH2)2X (R,R′ = Cl, Br, I, Me, Ph, M = CH2 S; X = NMe, O, S), RPh2SnCH2CH2CH2NMe2 (R = Cl, Br, I) and RMe2Sn—CHD—COOMe (R = F, Cl, Br, I, Me). In these hypervalent compounds an approach of the donor atom X to the central atom tin outlines a ‘path’ of nucleophilic attack from a tetrahedron to a trigonal bipyramid. Along this ‘reaction path’ the bond lengths of the axial ligand increase continuously while the bond lengths of the equatorial ligands slightly decrease. The number of similar hype…