44′-Bipyrazolyl:: new bitopic connector for construction of coordination networks

New organic bitopic connector 4,4'-bipyrazolyl (hpz) easily forms complexes with metal ions and produces 1, 2 and 3D coordination polymers of different topology. Ten coordination polymers based upon bpz ligand and octahedral metal centers (Zn2+, Cd2+, Cu2+, Co2+) have been prepared and characterized by means of X-ray analysis. In all compounds the bipyrazolyl molecules act as bridging neutral groups and connect two metal atoms at the distances of 9.81-10.34 Angstrom. Representative possibilities for the formation of multidimensional metal-organic array include linear chains in [Cu(bpz)(H2O)(3)(SO4)].H2O, 'ladder chains' in [M(bpz)(1.5)(H2O)(2)(NO3)](NO3) (M = CU, Zn), flat and corrugated square grid layers in 1:2 complexes with cobalt chloride, zinc and cadmium perchlorates and copper trifluoroacetate, parallel/parallel interpenetrated square grid layers in [Cd(bpz)(2)(NO3)(2)] and 3D diamondoid net in [Cu(hpz)(2)(H2O)(2)](CLO3)(2).5H(2)O With exception of the latter example the supramolecular architecture of metal-organic polymers may be clearly related with 4,4'-bipyridine derivatives, but more hydrophilic nature of pyrazole nuclei facilitates easy incorporation of different H-bond donors/acceptors-H2O, CH3OH, DMF. The 2D coordination arrays may enclathrate also guest molecules of hydrophilic aromatics that appear to be located between successive coordination layers: [CU(bpz)(2)(H2O)(2)](CF3CO2)(2).2H(2)O.C6H5OH. (C) 2002 Elsevier Science B.V. All rights reserved.