부산대학교 도서관

The extension of a series of polyalkylpyrazolyl-substituted 2-imidazoline nitronyl nitroxide radicals LR1/R2/R3 (R = Me, Et, Pr, Bu) enables the synthesis of a number of coordination polymers based on copper(II) bis(hexafluoroacetylacetonate) Cu(hfac)2 with LR1/R2/R3. As compared to breathing crystals (Cu(hfac)2 complexes with monoalkyl-substituted nitroxides LR1 with bridging μ2-O,N coordination), the introduction of the second substituent LR1/R2 into the pyrazole ring allows the performance of the tritopic function of the paramagnetic ligand (μ3-O,O,N) and the formation of 1D and 2D polymers with original structures and different combinations of [CuO6], [CuO5N], [CuO4N2], and [CuO5] coordination cores. Only molecular complexes are obtained with single 3-substituted nitroxide LR1/R2/R3–LMe3. The single crystal X-ray diffraction study of the structures of these compounds shows that as in the case of LMe3, an increase in the size of one of substituents in LR1/R2 to Pr or Bu causes an increase in distances between paramagnetic centers in two- and three-spin exchange clusters, and correspondingly, spin transitions are absent.