Abstract: It was established that the reactions of pyrazol-3-yl-substituted nitronyl nitroxide (HL1) and pyrazol-3-yl-substituted imino nitroxide (HL3) with Cu(II) acetate lead to self-assembly of the Cu4(OH)2(OAc)4(DMF)2(L1)2 tetranuclear and Cu2(OAc)2(H2O)2(L3)2 dinuclear complexes, respectively. The reaction of Cu(II) acetate with 5-ethoxycarbonyl-pyrazol-3-yl-substituted nitronyl nitroxide (HL2) gave unexpected solid Cu2(H2O)2(L6)2 Æ 2DMF, in which L6 is a deprotonated 5-carboxy-pyrazol-3-yl-substituted nitronyl nitroxide, formed as a result of cleavage of an ester bond in the starting HL2. A similar transformation of the paramagnetic ligand was observed in the reaction of Cu(II) acetate with 5-ethoxycarbonyl-pyrazol-3-yl-substituted imino nitroxide (HL4). It led to the formation of Cu2(DMF)2(L7)2, where L7 is deprotonated 2-(5-carboxy-1H-pyrazol-3-yl)-4,4,5,5-tetramethyl-4,5-dihydro-1H-imidazole 3-oxide. An X-ray diffraction study indicated that in Cu4(OH)2(OAc)4(DMF)2(L1)2 and Cu2(OAc)2(H2O)2(L3)2, the L1 and L3 paramagnetic ligands perform the bridging cyclic tridentate function, while in Cu2(H2O)2(L6)2 Æ 2DMF and Cu2(DMF)2(L7)2, the paramagnetic L6 and diamagnetic L7 are bridging bicyclic tetradentate ligands. The magnetic behavior of complexes with coordinated nitronyl nitroxide– Cu4(OH)2(OAc)4(DMF)2(L1)2 and Cu2(H2O)2(L6)2 Æ 2DMF is dictated by the dominant antiferromagnetic exchange interactions, which is confirmed by quantum-chemical data. The magnetic susceptibility of Cu2(OAc)2(H2O)2(L3)2 reflects the competition between the antiferromagnetic and ferromagnetic components, of which the latter is due to electron coupling in the Cu(II) N=C–N~O exchange channels. EPR data confirm the results received from static magnetic measurements for multispin solids.

Cite: Tretyakov E.V. , Tolstikov S.E. , Gorelik E.V. , Fedin M.V. , Romanenko G.V. , Bogomyakov A.S. , Ovcharenko V.I.
Copper(II) complexes with pyrazolyl-substituted nitronyl and imino nitroxides
Polyhedron. 2008. V.27. N2. P.739-749. DOI: 10.1016/j.poly.2007.11.003 WOS Scopus

Dates:

Published print:

Feb 6, 2008

Identifiers:

Web of science:	WOS:000253518700034
Scopus:	2-s2.0-38349000550

Citing:

DB	Citing
Scopus	20
Web of science	22

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