Copper(II) complexes with ethyl [(Pyrazolo-1-carbothioyl)-amino]acetate derivatives: Synthesis and structure

Optically active derivative of the natural monoterpene (+)-3-carene, namely, ethyl (3bS,4aR)-[(3,4,4-trimethyl-3b,4,4a,5 -tetrahydrocyclopropa [3,4]cyclopenta[1,2-c]pyrazole-1-carbothioyl)-amino]acetate (HLI) and ethyl [(3,5-dimethyl-pyrazole-1-carbothioyl)-amino] acetate (HL2) were synthesized. Paramagnetic complexes 2 [(CuLCl)-Cl-1](n) (I) and [Cu2L22 Cl-2] (II) were prepared. According to X-ray diffraction data, complex I with anion of (+)-3-carene derivative has chain structure, whereas complex II with anion of HL2, which has no carbocyclic fragments, is a pseudodimer. Organic anions act as tetradentate bridging, cyclic ligands forming five-membered CuN3C and CuNOC2 metal cycles. Coordination polyhedron of Cu(ClN2O + S) in complexes I and II is a square pyramid. The values of mu(eff) for complexes I and II (1.88 and 1.84 mu(B), respectively) are constant in the temperature interval 78-300 K, which means that the unpaired electrons of Cu(II) ions do not exhibit any noticeable exchange interactions.