MAGNETIC ANOMALIES IN POLYMERIC CHAIN COMPLEXES Cu(hfac)2 WITH SPIN-LABELED DIALKYLPYRAZOLES

The structures of hexafluoroacetylacetonate complexes of Cu(II)–Cu(hfac) 2 – with nitroxide radicals L R1/R2 , where R1 and R2 are alkyl substituents in the 1,3-pyrazole moiety are studied by X-ray crystallography. It is found that solid phases of all [Cu(hfac) 2 L R1/R2 ] are formed by polymeric chains whose common structural motif is a ditopic bridging coordination of paramagnetic ligands in the head-to-head fashion. The study of the temperature structure dynamics and the related change in the temperature dependence of the effective magnetic moment of the complex shows that changes in both R1 and R2 can substantially affect not only the possibility of the appearance of magnetic anomalies on the temperature curve of the effective magnetic moment but also its shape.