One- and two-dimensional coordination polymers of 3,3′,5,5′-tetramethyl-4,4′-bipyrazolyl, a new perspective crystal engineering module

The coordination polymers based upon new bidentate ligand 3,3′,5,5′-tetramethyl-4,4′-bipyrazolyl (4,4′-bpz) have been prepared and characterized by means of X-ray analysis. In all compounds Ag(4,4′-bpz)NO3·CH3OH (1), Cd(4,4′-bpz)(C3H7OH)(NO3)2 (2), Cd(4,4′-bpz)2(NO3)2 (3), Cu(4,4′-bpz)2(H2O)(BF4)2·0.5C6H5Br (4), and Cu(4,4′-bpz)2(H2O)(HCOO)2·2.5HCONH2 (5) the molecules of bipyrazolyl act as bridging neutral groups and connect two metal atoms at the distances of 9.58–10.25 Å. Complexes 1 and 2 exhibit one-dimensional polymeric structure, while compounds 3–5 exist as two-dimensional polymers, containing layers of four-connected coordination nets. In structures 4 and 5 the layers are interlinked by means of hydrogen bonding involving counter anions, which lead to formation of three-dimensional open networks capable of incorporation of hydrophilic (5) or hydrophobic (4) guest molecules. Geometry of coordination polymer in these cases is significantly dominated by the angular structure of 4,4′-bpz ligand, while structure of the coordination net in 3 is very similar for analogues containing linear 4,4′-bipyridine bridges.