ISSN:
1572-8951
Keywords:
Molecular magnetism
;
superexchange interaction
;
copper(II)-complex polymer
;
ferromagnetic polymer
;
extended Hückel method
Source:
Springer Online Journal Archives 1860-2000
Topics:
Chemistry and Pharmacology
Notes:
Abstract Magnetic interactions in the three copper(II)-complex polymers, [Cu(PZ)(NO3)2]n, [Cu(PM)(NO3)2(H2O)2]n, and [Cu(PM)2(NO3)2]n are discussed on the basis of extended Hückel calculations inthe formulas PZ and PM stand for pyrazine and pyrimidine, respectively. Interactions between the Cu-3d orbitals and the σ lone-pair orbitals of pyrazine and pyrimidine are analyzed from the viewpoint of `through-space' and `through-bond' interactions using binuclear complexes to model the three copper(II) polymers. Three conclusions can be drawn from the orbital interaction analysis: (1) in the first polymer, a superexchange pathway is formed with the σ bond of Cu–-N and the through-bond interaction between the lone pairs of the nitrogen atoms of pyrazine will lead to an antiferromagnet state; (2) in the second polymer a superexchange pathway is formed with the σ bond of Cu–-N and the through-space interaction between the lone pairs of the nitrogen atoms of pyrimidine, and as a result an antiferromagnetic state will be preferred; and (3) in the third polymer., there is no effective pathway in respect of overlap interaction and the HOMO and the LUMO are actually degenerate, and thus a ferromagnetic state will arise. The band structures are analyzed to characterize the magnetic properties of the antiferromagnetic polymers, [Cu(PZ)(NO3)2]n and [Cu(PM)(NO3)2(H2O)2], and the ferromagnetic polymer, [Cu(PM)2(NO3)2]n.
Type of Medium:
Electronic Resource
URL:
http://dx.doi.org/10.1023/A:1008300621000
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