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An interplay between the spin density distribution and magnetic superexchange interactions: a case study of mononuclear [(n)Bu(4)N](2)[Cu(opooMe)] and novel asymmetric trinuclear [Cu(3)(opooMe)(pmdta)(2)](NO(3))(2)·3MeCN.
MedLine Citation:
PMID:  23059964     Owner:  NLM     Status:  Publisher    
Abstract/OtherAbstract:
Treatment of the diethyl ester of o-phenylenebis(oxamic acid) (opbaH(2)Et(2), ) with 5/6 equivalent of MeNH(2) in abs. EtOH results in the exclusive formation of the ethyl ester of o-phenylene(N'-methyl oxamide)(oxamic acid) (opooH(3)EtMe, ) in ca. 50% yield. Treatment of with four equivalents of [Me(4)N]OH followed by the addition of Cu(ClO(4))(2)·6H(2)O gave [Me(4)N](2)[Cu(opooMe)]·H(2)O () in ca. 80% yield. As appears to be a hygroscopic solid, the related [(n)Bu(4)N](+) salts [(n)Bu(4)N](2)[M(opooMe)]·H(2)O (M = Cu (), Ni ()) have been synthesized. By addition of two equivalents of [Cu(pmdta)(NO(3))(2)] to a MeCN solution of the novel asymmetric trinuclear complex [Cu(3)(opooMe)(pmdta)(2)](NO(3))(2) () could be obtained in ca. 90% yield. Compounds , , , and have been characterized by elemental analysis and NMR/IR spectroscopy. Furthermore, the solid state structures of in the form of [Me(4)N](2)[Cu(opooMe)]·MeOH (), in the form of [(n)Bu(4)N](2)[Cu(opooMe)] (), in the form of [(n)Bu(4)N](2)[Ni(opooMe)]·1.25H(2)O () and in the form of [Cu(3)(opooMe)(pmdta)(2)] (NO(3))(2)·3MeCN (), respectively, have been determined by single-crystal X-ray diffraction studies. By controlled cocrystallization, diamagnetically diluted (1%) in the host lattice of (99%) in the form of single crystals have been made available, allowing single crystal EPR studies to extract all components of the g-factor and the tensors of onsite (Cu)A and transferred (N)A hyperfine interaction. Out of these studies the spin density distribution of the [Cu(opooMe)](2-) complex fragment could be determined. The magnetic properties of were studied by susceptibility measurements versus temperature. An intramolecular J parameter of -65 cm(-1) has been obtained, unexpectedly, as should possess two different J values due to its two different spacers between the adjacent Cu(II) ions, namely an oxamate (C(2)NO(3)) and an oxamidate (C(2)N(2)O(2)) fragment. This unexpected result is explained by a summarizing discussion of the experimentally obtained EPR results (spin density distribution) of , the geometries of the terminal [Cu(pmdta)](2+) fragments of determined by X-ray crystallographic studies and accompanying quantum chemical calculations of the spin density distribution of the mononuclear [Cu(opooMe)](2-) and of the magnetic exchange interactions of trinuclear [Cu(3)(opooMe)(pmdta)(2)](2+) complex fragments.
Authors:
Mohammad A Abdulmalic; Azar Aliabadi; Andreas Petr; Yulia Krupskaya; Vladislav Kataev; Bernd Büchner; Torsten Hahn; Jens Kortus; Tobias Rüffer
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Publication Detail:
Type:  JOURNAL ARTICLE     Date:  2012-10-12
Journal Detail:
Title:  Dalton transactions (Cambridge, England : 2003)     Volume:  -     ISSN:  1477-9234     ISO Abbreviation:  Dalton Trans     Publication Date:  2012 Oct 
Date Detail:
Created Date:  2012-10-12     Completed Date:  -     Revised Date:  -    
Medline Journal Info:
Nlm Unique ID:  101176026     Medline TA:  Dalton Trans     Country:  -    
Other Details:
Languages:  ENG     Pagination:  -     Citation Subset:  -    
Affiliation:
Technische Universität Chemnitz, Fakultät für Naturwissenschaften, Strasse der Nationen 62, D-09111 Chemnitz, Germany. tobias.rueffer@chemie.tu-chemnitz.de.
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