catena-Poly[[aquazinc(II)]-μ-N,N′-bis(2-cyano-3-ethoxy-3-oxoprop-1-enyl)benzene-1,2-diaminido]

Abstract

The slightly yellow-coloured title complex, [Zn(C18H16N4O4)(H2O)]n, crystallizes with one mol­ecule in the asymmetric unit. The structure clearly shows the mer-η4 O,O,N,N-binding mode of the N,N′-bis-(2-cyano-ethyl­propeno­yl)-1,2-di­amido­benzene ligand stabilizing the Zn centre of a distorted octa­hedral environment. The fifth coordination site in one apical position is held by a coordinating solvent water mol­ecule whereas the complete octa­hedral coordination sphere is completed by coordination of one N atom from a CN group of a neighbouring mol­ecule, leading to the final polymeric structure consisting of zigzag staggered chains in parallel orientation along the c-axis direction. Between the coord­in­ated water solvent molecule and the N atoms of uncoord­in­ated cyano-groups of neighboured units, two H-bridge bonds are formed. One of these H-bridge bonds is of inter- whereas the other of intra-strand nature, leading to a two-dimensional network parallel to (110) stabilizing the supramolecular structure. Six Zn—O or Zn—N bonds are found with lengths ranging from 2.061 (1) to 2.185 (1) Å and bond angles about the Zn atom are clustered in the ranges 79.83 (4)–104.21 (4) and 167.05 (4)–170.28 (4)°.

New zinc catalysts based on easy-to-handle N4-chelating ligands for the coupling reaction of epoxides with CO2

“…Once isolated the bpb-zinc-complexes are stable, building aquo-zinc-complexes under normal atmosphere, the water being directly coordinated at the metallic center as already found in earlier study dealing with N 2 O 2 -zinc complexes [19]. The traces of water that remains in the solid after the standard drying procedure (3-4 h at 60 • C under vacuum) represent no threat for the catalysts and the selectivity of the reaction (no detectable hydrolysis products).…”