Dicyanamido-metal(II) complexes. Part 3: Hydrolysis of the dicyanamide into amidocyanamide during its interaction with Cu(II) perchlorate and 2-pyridylcarbonyl-N,N-bis(2-pyridylmethyl)amine

(T)he reaction of Cu(ClO4)(2), 2-pyridylcarbonyl-N,N-bis(2-pyridylmethyl)amine (DPA-CO-py) and sodium dicyanamide (Nadca) in aqueous medium led to the isolation of three complexes: {[Cu(DPA)(mu(1,5)-dca)]-ClO4}(n) (1), [Cu-2(pic)(2)(mu(1.3)-H2NCO-N-CN)(2)(H2O)(2)] center dot 2H(2)O (2) and Cu(pic)(2) center dot H2O (3). The Cu2+ ion, during its complex formation with DPA-CO-py and dca not only assisted the hydrolysis of DPA-CO-py to the corresponding di(2-methylpyridyl)amine (DPA) and picolinic acid (Hpic) but also resulted in partial hydrolysis of one of the two nitrile groups of the dicyanamide, NC-N-CN- (dca) to amidocynamide, H2NCO-NH-CN. The complexes were structurally characterized and the single X-ray structures for 1 and 2 reveal their identity. Complex 1 forms a 1D polymeric chain with the dca acting as a mu(1.5)-bridging ligand via the terminal nitrile nitrogen atoms. A distorted SP geometry around the Cu2+ centers was achieved by the three N-atoms of the DPA and by the two nitrile groups of the bridging dca ligands. Complex 2 consists of a dimeric unit with CuN3O2 chromophore in coordination polyhedron that has a distorted SP geometry. The amidocyanamide ion, H2NCO-N-CN- acts as bis(monodentate) mu(1.3)-bridging ligand via the central amido and terminal nitrile nitrogen atoms whereas the picolinate anion forms a six-membered chelate ring through its pyridyl nitrogen and an oxygen atom of the carboxylate group, and the aqua water occupies the apical position of the structure. Complex 1 exhibits very weak anti ferromagnetic coupling (J = -0.31 cm(-1)) whereas 2 shows a significant antiferromagnetic interaction between the two copper centers (J = -13.6 cm(-1)). (c) 2009 Elsevier B.V. All rights reserved.