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, [Zn-2(mu-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), [Zn-2(mu-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 Zn-2(Hdmpz)(4)(L5)(2)center dot 3H(2)O (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 center dot center dot center dot O H-bond from Hdmpz and ClO4- was present in 1. The coordinated O of CO2- in 2 accepts an intramolecular N-H center dot center dot center dot 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 center dot center dot center dot O H-bond with N-H of the Hdmpz. Compound 6 has intramolecular N-H center dot center dot center dot O H-bonds from the Hdmpz, the uncoordinated O and H2O. The intricate intra- and intermolecular classical H-bonds, Br center dot center dot center dot O, CH center dot center dot center dot Cl, CH3 center dot center dot center dot Cl, CH center dot center dot center dot Br, C-H center dot center dot center dot O, CH3 center dot center dot center dot O, C center dot center dot center dot pi, O center dot center dot center dot pi, O center dot center dot center dot C, Cl-pi, C-H center dot center dot center dot pi and CH3 center dot center dot center dot pi associations are elucidated by X-ray crystallographic studies, which convert discrete units into high-dimensional ordered supramolecular structures.