Synthesis, X-ray structures, and magnetic properties of seven polynuclear Cu(ii) complexes containing pyrazole-3,5-dicarboxylate with various ancillary ligands†
Abstract
A series of polynuclear Cu(II) complexes, namely, (Him)2[Cu2(pzdc)2(H2O)2] (1), [Cu3(pzdc)2(im)2(H2O)4] (2), {[Na4Cu4(pzdc)4(im)4(H2O)2]·16H2O}n (3), (Hamp)2[Cu2(pzdc)2(H2O)2] (4), (H2tmdp)2[Cu4(pzdc)4(H2O)2]·2H2O (5), {[Cu2(pzdc)2][Cu(H2O)6]}n (6), and [Cu3(pzdc)2(en)2(H2O)2]n (7), were successfully synthesized under the reaction of Cu(NO3)2·3H2O, pyrazole-3,5-dicarboxylic acid, and various ancillary ligands (im = imidazole, amp = 4-aminopyridine, tmdp = 4,4′-trimethylenedipyridine, and en= ethylenediamine). The magnetic study based on the secondary building Cu(II) unit with pyrazole-3,5-dicarboxylate bridges can be divided into three groups: (Group I) dinuclear Cu(II) units of 1, 4, and 6, (Group II) trinuclear Cu(II) units of 2 and 7, and (Group III) tetranuclear Cu(II) units of 3 and 5. The magnetic properties of 1 and 4 (group I) exhibit spin-canted antiferromagnetism while 6 exhibits typical antiferromagnetic coupling within the Cu(II) dimer with the paramagnetism from the [Cu(H2O)6]2+ unit. Group II exhibits antiferromagnetic interactions within the Cu(II) trimer for 2 and 7. Group III displays antiferromagnetic and weak ferromagnetic interactions within the tetranuclear Cu(II) unit.
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