Copper(II) carboxylate dimers and chains

Copper(II) carboxylates have been synthesized to develop a magnetostructure function relationship. The pseudopolymorphs Cu2a(OH2)(2).H2O and Cu(2)a(OH 2)(2) (2a = 1,4-benzenedicarboxylate (terephthalate)) form 1-D (theta = -7. 2 K; J/kB = -9.15 K (H = -2JS(1) . S-2)) and 2-D layers with ferromagnetic coupling (theta = +0.8 K), respectively. In contrast, formation of isolated dimers of (CU2(O2CMe)(3)(3)(EtOH)(2)) (3 = 2-(4 ' -carboxyphenyl)-4,4,5,5- tetramethyliniidazoline-3-oxide-1-oxyl) enables the coupling of S = 1/2 spi ns on the nitroxides to the S = 1 excited state of the copper(II) dimer. Th is coupling of -157 K is two orders of magnitude greater than the S = 1/2 n itroxide-nitroxide coupling of -1.5 K. (C) 2001 Elsevier Science B.V. All r ights reserved.