Chains, helices, sheets and unusual 3D nets: Diverse structures of the flexible, ditopic ligand 1,2-bis(3-(4-pyridyl)pyrazolyl)ethane

The flexible ditopic ligand 1,2-bis(3-(4-pyridyl)pyrazol-1-yl)ethane (L4Et) displays remarkable versatility in the complexes that it forms with transition metals with products ranging from 1D chains to interpenetrating 3D networks. The L4Et ligand itself crystallises in the space group P21, adopting a helical twist, although it is found in a variety of other conformations in its complexes. Coordination polymers containing the L4Et ligand vary from almost straight, parallel 1D chains of [Ag2(L4Et)2(ClO4)2(DMF)]·DMF (1), through interdigitating helical complexes containing tetrahedral Zn(II), [Zn(NCS)2(L4Et)]·DMF·H2O (2) to 2D sheets of [Cu(L4Et)2(H2O)2](PF6)2·xH2O (3) and the three-fold interpenetrating 3D network of [Co(L4Et)2(NCS)2] (4). The 3D network adopts an unusual 3D 4-connected dmp (65.8) topology. Dimensionality can be limited by the use of chelating co-ligands, demonstrated by the formation of the dinuclear complex [{Cu(py-2,6-CO2)(H2O)}2(L4Et)] (5).

Graphical abstractThe flexible ditopic ligand 1,2-bis(3-(4-pyridyl)pyrazol-1-yl)ethane (L4Et) displays remarkable versatility in the complexes that it forms with transition metals with products ranging from 1D chains to interpenetrating 3D networks with unusual dmp topology.Figure optionsDownload full-size imageDownload as PowerPoint slide