New bi- and trinuclear copper(ii) complexes of aroylhydrazones of TFA and benzenecarboxylic acids were synthesized and characterized. Despite long range intramolecular CuCu distances of about 10 Å, exchange couplings between paramagnetic centres are observed with J values of 0.33 and 0.37 cm(-1) in binuclear complexes, and -0.33 cm(-1) in trinuclear complexes. Seven hyperfine peaks with a value of aCu = 37.0 × 10(-4) cm(-1) are observed in EPR spectra of binuclear complexes. The possible mechanisms responsible for the observed weak long range coupling via aromatic spacers are discussed.
An exchange reaction of the sodium salt of 3 methyl 1 phenyl 4 formylpyrazol 5 one (HL) with chlorides or nitrates of lanthanides (Ln = La, Nd, Sm, Eu, Gd, Tb, Dy, and Yb) was used to synthesize coor dination compounds of composition LnL 3 ⋅ nSolv (Solv = H 2 O or EtOH). According to powder X ray dif fraction data, these compounds constitute two series: one comprises lanthanum and neodymium complexes, and the other, samarium, europium, gadolinium, terbium, dysprosium, and ytterbium complexes. For the complexes of the first series, the structure was solved in a single crystal diffraction experiment carried out on [La 2 (μ L) 3 (L) 3 (H 2 O) 3 ] ⋅ 2MeOH. The lanthanum atoms in the complex are at a distance of 4.222(2) Å from each other, and they are structurally nonequivalent and linked by three 5 hydroxy 4 formylpyrazole anions. Solid phase samples of the coordination compounds under study feature weak luminescence in the spectral regions intrinsic to lanthanide cations.
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