Abstract: A 12-nuclear heterospin complex of Cu(II) hexafluoroacetylacetonate with dialkylpyrazolyl-substituted nitroxide [Cu2(hfac)4LBu/Et]6 is found, which has a previously unknown molecular structure for heterospin compounds where six {Cu(hfac)2(LBu/Et)} moieties form a 42-membered metallacycle. The ditopic function of connecting organic bridges between Cu atoms is performed by paramagnetic LBu/Et ligands forming a head-to-tail motif inside the metallacycle due to the coordination of the nitrogen atoms of the pyrazole ring (NPz) and one of the oxygen atoms (ONO) of the nitronyl nitroxide moiety. Each LBu/Et completes its structural function to tritopic due to the coordination of the second ONO atom by yet another Cu(hfac)2 moiety. Butyl substituents of the pyrazole moiety tightly fill the space inside the metallacycle, preventing the inclusion of any solvent molecules. Ethyl substituents of the pyrazole rings, methyl groups of the imidazoline moiety, and trifluoromethyl groups of hexafluoroacetylacetonate anions directed into the intermolecular space push the metallacycles apart. As a result, the neighboring metallacycles are magnetically isolated from each other, and the character of the temperature dependence of the effective magnetic moment is determined by strong antiferromagnetic interactions between nitroxides and terminal Cu(hfac)2 moieties inside 12-nuclear molecules. Because of these interactions, below 160 K only spins of intracyclic Cu(II) ions, weakly interacting with each other, contribute to the magnetic susceptibility.

Cite: Romanenko G.V. , Fokin S.V. , Chubakova E.T. , Tretyakov E.V. , Bogomyakov A.S. , Ovcharenko V.I.
STRUCTURAL FEATURES OF THE 12-NUCLEAR Cu(hfac)2 COMPLEX WITH SPIN-LABELED PYRAZOLE
Journal of Structural Chemistry. 2021. V.62. N12. P.1857-1862. DOI: 10.1134/s0022476621120052 WOS Scopus OpenAlex

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Web of science:	WOS:000734031400005
Scopus:	2-s2.0-85121721898
OpenAlex:	W4200217303

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