Radical-ion salts obtained from tetraazaderivatives of nickel and copper and tetracyanoquinodimethane: structural and magnetic characterization
| Autor: | M. Teresa Azcondo, Loreto Ballester, Angel Gutiérrez, M. Felisa Perpiñán, Ana Sánchez, M Jesús González |
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| Rok vydání: | 2004 |
| Předmět: |
Inorganic chemistry
Supramolecular chemistry chemistry.chemical_element Crystal structure Magnetic susceptibility Tetracyanoquinodimethane Inorganic Chemistry Perchlorate chemistry.chemical_compound Crystallography Nickel chemistry Radical ion Materials Chemistry Physical and Theoretical Chemistry Triplet state |
| Zdroj: | Inorganica Chimica Acta. 357:1054-1062 |
| ISSN: | 0020-1693 |
| DOI: | 10.1016/j.ica.2003.09.022 |
| Popis: | Several derivatives of formulae [M(N4)(TCNQ)2] and [M(N4)(TCNQ)2](TCNQ) (M = Ni, Cu; N4 = 1,4,7,10-tetraazacyclododecane ([12] aneN4), 1,4,8,11-tetraazacyclotetradecane ([14] aneN4), 1,4,8,12-tetraazacyclopentadecane ([15] aneN4), 1,4,7,10-tetraazadecane (trien), N,N,N-tris(2-aminoethyl)amine (tren), 5,7,7,12,14,14-hexamethyl-1,4,8,11-tetraazacyclotetradeca-4,14-diene (trans-dieneN4)) have been obtained by metathesis reaction of the corresponding perchlorate or nitrate derivatives and LiTCNQ or (Et3NH)(TCNQ)2. The compounds [M(aneN4)(TCNQ)2] have a six coordinated metal atom surrounded by the four macrocyclic nitrogens and two nitrogens from σ coordinated TCNQ−. The overlap with a neighbouring 7,7,8,8-tetracyanoquinodimethane (TCNQ) forms the diamagnetic dianion [TCNQ]22−, and the whole structure can be seen as chains of metallomacrocyclic cations and TCNQ dianions alternating in the solid. The crystal structure of [Cu([15] aneN4)(TCNQ)2] confirms this fact. With open chain tetraamines the derivatives [Cu(trien)(TCNQ)2] and [Cu(tren)(TCNQ)2] are proposed to have the copper in a pentacoordinated environment, with only one coordinated TCNQ. In [M(trans-dieneN4)](TCNQ)2 both TCNQ− are uncoordinated and dimerized, as the crystal structure of the nickel derivative confirms. The derivatives with three TCNQ [M(aneN4)(TCNQ)2](TCNQ) are proposed to have a structure derived from that of the analogous [M(aneN4)(TCNQ)2], based on the metallomacrocycle-[TCNQ]2 chains connected through the extra TCNQ which remains uncoordinated and overlaps with the coordinated anions. This fact lowers the antiferromagnetic coupling inside the dimers and a small contribution for a thermally activated triplet state is observed in the magnetic susceptibility of these compounds. |
| Databáze: | OpenAIRE |
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