NDLI: Magnetic superexchange interactions: trinuclear bis(oxamidato) versus bis(oxamato) type complexes

Content Provider	World Health Organization (WHO)-Global Index Medicus
Author	Büchner, Bernd Rüffer, Tobias Kortus, Jens Aliabadi, Azar Krupskaya, Yulia Schaarschmidt, Dieter Abdulmalic, Mohammad A. Petr, Andreas Zaripov, Ruslan Voronkova, Violeta Hahn, Torsten Salikov, Kev Vavilova, Evgeniya Kataev, Vladislav Eya'ane Meva, Francois
Description	Author Affiliation: Abdulmalic MA ( Technische Universität Chemnitz, Fakultät für Naturwissenschaften, Strasse der Nationen 62, D-09111 Chemnitz, Germany. tobias.rueffer@chemie.tu-chemnitz.de.)
Abstract	The diethyl ester of o-phenylenebis(oxamic acid) $(opbaH_{2}Et_{2})$ was treated with an excess of $RNH_{2}$ in MeOH to cause the exclusive formation of the respective o-phenylenebis(N(R)-oxamides) $(opboH_{4}R_{2},$ R = Me 1, Et 2, $^{n}Pr$ 3) in good yields. Treatment of 1–3 with half an equivalent of $[Cu_{2}(AcO)_{4}(H_{2}O)_{2}]$ or one equivalent of $[Ni(AcO)_{2}(H_{2}O)_{4}]$ followed by the addition of four equivalents of $[^{n}Bu_{4}N]OH$ resulted in the formation of mononuclear bis(oxamidato) type complexes $[^{n}Bu_{4}N]_{2}[M(opboR_{2})]$ (M = Ni, R = Me 4, Et 5, $^{n}Pr$ 6; M = Cu, R = Me 7, Et 8, $^{n}Pr$ 9). By addition of two equivalents of $[Cu(pmdta)(NO_{3})_{2}]$ to MeCN solutions of 7–9, novel trinuclear complexes $[Cu_{3}(opboR_{2})(L)_{2}](NO_{3})_{2}$ (L = pmdta, R = Me 10, Et 11, $^{n}Pr$ 12) could be obtained. Compounds 4–12 have been characterized by elemental analysis and NMR/IR spectroscopy. Furthermore, the solid state structures of 4–10 and 12 have been determined by single-crystal X-ray diffraction studies. By controlled cocrystallization, diamagnetically diluted 8 and 9 (1%) in the host lattice of 5 and 6 (99%) (8@5 and 9@6), respectively, in the form of single crystals have been made available, allowing single crystal ESR studies to extract all components of the g-factor and the tensors of onsite $^{Cu}A$ and transferred $^{N}A$ hyperfine (HF) interaction. From these studies, the spin density distribution of the $[Cu(opboEt_{2})]^{2−}$ and $[Cu(opbo^{n}Pr_{2})]^{2−}$ complex fragments of 8 and 9, respectively, could be determined. Additionally, as a single crystal ENDOR measurement of 8@5 revealed the individual HF tensors of the N donor atoms to be unequal, individual estimates of the spin densities on each N donor atom were made. The magnetic properties of 10–12 were studied by susceptibility measurements versus temperature to give J values varying from −96 $cm^{−1}$ (10) over −104 $cm^{−1}$ (11) to −132 $cm^{−1}$ (12). These three trinuclear $Cu^{II}-containing$ bis(oxamidato) type complexes exhibit J values which are comparable to and slightly larger in magnitude than those of related bis(oxamato) type complexes. In a summarizing discussion involving experimentally obtained ESR results (spin density distribution) of 8 and 9, the geometries of the terminal $[Cu(pmdta)]^{2+}$ fragments of 12 determined by crystallographic studies, together with accompanying quantum chemical calculations, an approach is derived to explain these phenomena and to conclude if the spin density distribution of mononuclear bis(oxamato)/bis(oxamidato) type complexes could be a measure of the J couplings of corresponding trinuclear complexes.
ISSN	14779226
Issue Number	17
Journal	Dalton Trans.
Volume Number	44
e-ISSN	13645447
Language	English
Publisher	Royal Society of Chemistry
Publisher Date	2015-05-07
Publisher Place	Great Britain (UK)
Access Restriction	Subscribed
Subject Keyword	Chemistry
Content Type	Text
Resource Type	Article
Subject	Inorganic Chemistry

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