Palladium(II) complexes obtained from 3,4-bis(cyanamido)cyclobutane-1,2-dione dianion

摘要

Three palladium(II) complexes have been synthesized, using 3,4-bis(cyanamido) cyclobutane-1,2-dione dianion (3,4-bis(cyanamido)squarate or 3,4-NCNsq(2-)): [Pd(en)(3,4-NCNsq)] (.) 1.5H(2)O (1) (en = 1,2-diaminoethane), [Pd(en)(3,4-(NC(O)NH2)sq)] (.) 0.5H(2)O (2) and K3Na[Pd-2(3,4-(NCN)(2)sq)(4)] (.) 5H(2)O (3). Complex 1 has been characterized by elemental analysis, IR and C-13 NMR spectroscopies. Complexes 2 and 3 have been characterized by single-crystal X-ray diffraction. In complex 2, the unusual hydration of the cyanamido ligand was observed, it proceeds in the coordination sphere of the palladium and leads to a chelating urea squarate ligand. Complex 3 is an anionic dinuclear complex containing four bridging cyanamido squarate ligands. In complexes 2 and 3, the 3,4-NCNsq2- ligand (hydrated or not) is, for the first time, coordinated to the metal atom by the two amido nitrogen atoms, either in a chelating mode (complex 2) or in a bridging mode giving a short Pd (...) Pd distance of 2.8866(15) Angstrom (complex 3). Electrochemical studies in acetonitrile and dmf solutions have been performed on complexes 1 and 3. (C) 2003 Elsevier B.V. All rights reserved. [References: 49]