Your browser doesn't support javascript.
Mostrar: 20 | 50 | 100
Resultados 1 - 7 de 7
Filtrar
Mais filtros










Base de dados
Intervalo de ano de publicação
1.
Inorg Chem ; 48(13): 5617-9, 2009 Jul 06.
Artigo em Inglês | MEDLINE | ID: mdl-19492819

RESUMO

Cyanide-bridged M(V)-Mn(III) (M = Mo, W) bimetallic chain complexes with racemic spatial dispositions were constructed by self-assembling [M(CN)(8)](3-) precursors and Mn(III) Schiff bases. Antiferromagnetic couplings between spin centers within a chain result in a ferrimagnetic nature, and slow magnetic relaxations are observed as well.


Assuntos
Magnetismo , Metais/química , Ligação de Hidrogênio , Modelos Moleculares , Estrutura Molecular , Estereoisomerismo
2.
Inorg Chem ; 48(3): 816-8, 2009 Feb 02.
Artigo em Inglês | MEDLINE | ID: mdl-19102632

RESUMO

A cyanide-linked Ru(III)(4d)-Mn(III)(3d) bimetallic chain complex (1) was prepared by the self-assembly of a ruthenium(III) bicyanide and a Mn(III) Schiff base. Ferromagnetic couplings between the magnetic centers are present within a chain, while antiferromagnetic interactions between chains (T(N) = 2.5 K) transmit. Complex 1 also shows a field-induced magnetic phase transition.

3.
Inorg Chem ; 46(25): 10578-86, 2007 Dec 10.
Artigo em Inglês | MEDLINE | ID: mdl-17985870

RESUMO

Four octacyanometalate-based bimetallic Cu-M (M = Mo, W) assemblies coordinated by tetradentate macrocyclic ligands were prepared via self-assembly process in a stoichiometric ratio of [M(CN)8]3- and Cu(macrocycle)2+ and characterized in terms of structures and magnetic properties. The crystal structures are varied depending on the macrocycles used. The employment of cyclam with no pendant groups produced a one-dimensional chain (1) with a rope-ladder pattern, whereas macrocycles with side groups allowed for the formation of two-dimensional honeycomb-like architectures (2-4). From the crystal structures, the variations in apical Cu-Nax lengths and Cu-Nax-Cax angles on the bridging pathways are observed, which arises from the existence of side groups on macrocyclic ligands. The magnetic results reveal that all of the prepared compounds show ferromagnetic couplings between magnetic centers transimitted through CN bridges under the present structural parameters. Comparing the magnetic strength of the Cu-Mo (3d-4d; 2) and Cu-W (3d-5d; 3) complexes supports that 3d-5d magnetic coupling is stronger than 3d-4d because the 5d orbital is more diffuse than 4d. The magnetic analyses for 1-4 and related complexes tentatively suggest that, when the Cu-Nax distances are long enough, the axial Cu-Nax bond length in the bridging route may be one of the major structural parameters to determine the magnitude of the ferromagnetic exchange coupling.


Assuntos
Quelantes/química , Cobre/química , Cianatos/química , Compostos Macrocíclicos/química , Magnetismo , Molibdênio/química , Tungstênio/química , Cristalografia por Raios X , Cianatos/síntese química , Ligantes , Modelos Moleculares , Estrutura Molecular
4.
Inorg Chem ; 46(25): 10461-3, 2007 Dec 10.
Artigo em Inglês | MEDLINE | ID: mdl-18001123

RESUMO

The use of a new precursor, mer-[Fe(mpzcq)(CN)3]- (1), produced a dimeric molecule, [Fe(mpzcq)(CN)3][Mn(salen)(H2O)] x H2O (2), and a one-dimensional zigzag chain, [Fe(mpzcq)(CN)3][Mn(salcy)] x MeOH x MeCN (3). Antiferromagnetic couplings are operating between magnetic centers through CN ligands, and a field-induced metamagnetic transition is observed in 3.

5.
Inorg Chem ; 46(21): 8481-3, 2007 Oct 15.
Artigo em Inglês | MEDLINE | ID: mdl-17850146

RESUMO

A new cyanide-bearing molecular precursor, mer-[Fe(pzcq)(CN)(3)]- (1), and a zigzag chain, [Fe(pzcq)(CN)(3)][Mn(salen)].4H(2)O (2), were prepared and characterized in terms of structure and magnetism. Magnetic data reveal that intrachain antiferromagnetic couplings via cyanide ligands in 2 are clearly operating, resulting in a ferrimagnetic nature.


Assuntos
Química Inorgânica/métodos , Ferricianetos/química , Ferro/química , Cristalografia por Raios X/métodos , Cianetos/análise , Compostos Férricos/química , Ligantes , Magnetismo , Conformação Molecular , Estrutura Molecular , Oscilometria , Temperatura
6.
Inorg Chem ; 46(22): 9054-6, 2007 Oct 29.
Artigo em Inglês | MEDLINE | ID: mdl-17900108

RESUMO

A new one-dimensional heterochiral coordination polymer [Co(bmdt)(N3)2].MeCN (1.MeCN) with well-isolated chains was prepared via a self-assembly process. Magnetic data show that intrachain ferromagnetic couplings via the single end-to-end azide group are observed, which is an extraordinary case among the azide-bridged Co(II) systems.


Assuntos
Azidas/química , Cobre/química , Ferro/química , Magnetismo , Modelos Moleculares
7.
Dalton Trans ; (20): 2070-6, 2007 May 28.
Artigo em Inglês | MEDLINE | ID: mdl-17502941

RESUMO

Two W(V)-Mn(III) bimetallic compounds, [Mn(Cl-salmen)(H(2)O)2]{[Mn(5-Clsalmen)(H(2)O)]2[W(CN)8].2H(2)O (1.2H(2)O) [5-Clsalmen = N,N'-(1-methylethylene)bis(5-chlorosalicylideneiminato) dianion], which contains trinuclear Mn(2)W and isolated Mn(III) moieties, and [Mn(3-MeOsalcy)(H(2)O)2]3[W(CN)(8)].2H(2)O (2.2H(2)O) [3-MeOsalcy = N,N'-(trans-1,2-cyclohexanediylethylene)bis(3-methoxysalicylideneiminato) dianion] molecules were prepared in redox processes and characterized using X-ray analysis and magnetic measurements. Compound 1 is composed of the {[Mn(5-Clsalmen)(H(2)O)]2[W(CN)8]}- trimer, in which two CN groups among eight in [W(CN)8](3-) bridge W(5+) and two Mn(3+) ions and the remaining CN ligands are hydrogen-bonded to water molecules or unbound, and the [Mn(Cl-salmen)(H(2)O)2]+ cation. Subsequently, two water molecules of the isolated cation are subject to hydrogen bonds. For 2, there are no covalent bonds among the subunits and six serial stacks of [Mn(3-MeOsalcy)(H(2)O)2]+ units are all hydrogen-bonded. The many hydrogen bonds found in both complexes eventually lead to three-dimensional networks. The magnetic studies for 1 reveal that antiferromagnetic interactions (J = -5.4 cm(-1)) between W(V) and Mn(III) centers within the trimer are transmitted via the bridging CN groups. Intermolecular antiferromagnetic couplings (zJ' = -0.2 cm(-1)) are also observed. The static and dynamic magnetic data of 1 demonstrate the existence of a field-induced spin-flop transition occurring among the clusters and monomeric molecules.


Assuntos
Cianetos/química , Compostos Férricos/química , Magnetismo , Manganês/química , Compostos Organometálicos/química , Bases de Schiff/química , Compostos de Tungstênio/química , Cátions , Ligação de Hidrogênio , Isomerismo , Estrutura Molecular , Oxirredução , Temperatura
SELEÇÃO DE REFERÊNCIAS
DETALHE DA PESQUISA