Construction of six Zn2+/Cd2+ supramolecules from 3,5-dimethylpyrazole: their synthesis and characterization

The present report pertains to the synthesis and characterization of six complexes, [Zn2(μ-dmpz)2(Hdmpz)2(H2O)2](ClO4)2 (1) (Hdmpz = 3,5-dimethylpyrazole, dmpz = 3,5-dimethylpyrazolate), Cd(Hdmpz)(L1)2 (2) (L1 = 2-methylbenzoate), [Zn2(μ-dmpz)2(Hdmpz)2(L2)2] (3) (L2 = 3-chlorobenzoate), Zn(Hdmpz)2(L3)2 (4) (L3 = 3,4-dichlorobenzoate), Cd(Hdmpz)4(L4)2 (5) (L4 = 5-bromosalicylate), and Zn2(Hdmpz)4(L5)2·3H2O (6) (L5 = fumarate). These complexes were characterized by EA, IR, SCXRD analysis, and TGA.The X-ray studies show that these complexes have mononuclear to dinuclear structures with tetrahedral/octahedral arrangement around each Zn2+/Cd2+. The Hdmpzs in 2 and 4–6 are monodentate ligated via its neutral N, while 1 and 3 have neutral Hdmpzs and the ionic dmpzs. The CO2− of 3–6 is only monodentate. Compound 2 has both monodentate bridging and chelating bidentate CO2-.Intramolecular N–H···O H-bond from Hdmpz and ClO4- was present in 1. The coordinated O of CO2- in 2 accepts an intramolecular N–H···O H-bond from N-H of the Hdmpz and uncoordinated O of the CO2- in 3, 4 and 5 has an intramolecular N–H···O H-bond with N-H of the Hdmpz. Compound 6 has intramolecular N–H···O H-bonds from the Hdmpz, the uncoordinated O and H2O. The intricate intra- and intermolecular classical H-bonds, Br···O, CH···Cl, CH3···Cl, CH···Br, C–H···O, CH3···O, C···π, O···π, O···C, Cl-π, C–H···π and CH3···π associations are elucidated by X-ray crystallographic studies, which convert discrete units into high-dimensional ordered supramolecular structures.