Transition metal complexes with pyrazole-based ligands. Part 28. Synthesis, structural, DFT and thermal studies of cadmium(II) halides and zinc(II) chloride complexes with 3,5-dimethylpyrazole-1-carboxamidine

A binuclear Cd(II) complex containing bridging pyrimidine-based ligands

In this work, a pyrimidine-based ligand, N′-(amino(pyrimidin-2-yl)methylene)pyrimidine-2-carbohydrazonamide hydrate (APPH · H2O), and its binuclear complex of cadmium, [Cd(μ-APPH)Br]2, 1, were prepared and identified by elemental analysis, FT-IR, 1H NMR spectroscopy as well as single-crystal X-ray diffraction. X-ray structure analysis of 1 revealed octahedrally coordinated cadmium centers with a CdN4Br2 environment containing two bridging APPH ligands; each APPH ligand acts as an N4-donor (N2-donor toward each cadmium atom) and forms two five-membered chelate rings that are approximately perpendicular to each other. In the network of 1, the N–H · · · Br hydrogen bonds form motifs such as R 2 2 ( 12 ,   14 ) ,  R 6 6 ( 24 ,   26 ,   … ,   46 ) . ${\rm{R}}_{\rm{2}}^{\rm{2}}(12,{\rm{ }}14),{\rm{ R}}_{\rm{6}}^{\rm{6}}(24,{\rm{ }}26,{\rm{ }} \ldots ,{\rm{ }}46).$ The crystal network is further stabilized by π-π stacking interactions between pyrimidine rings. The optimized structures of the ligand and complex were investigated along with their charge distribution patterns by density functional theory and natural bond orbital analysis, respectively.

Crystal structure of meso-di-μ-chlorido-bis-[bis-(2,2'-bi-pyridine)-cadmium] bis-(1,1,3,3-tetra-cyano-2-ethoxy-propenide) 0.81-hydrate

The hydrated title salt, [Cd2Cl2(C10H8N2)4](C9H5N4O)2·0.81H2O, was obtained from the hydro-thermal reaction between 2,2'-bi-pyridine, cadmium(II) chloride and potassium 1,1,3,3-tetra-cyano-2-eth-oxy-propenide. The binuclear cation lies across a centre of inversion in the space group P21/c, with the other components in general positions. The cation has approximate, but non-crystallographic 2/m symmetry and each of the CdII atoms is a stereogenic centre, one having the Δ configuration and the other the Λ configuration. In the anion, one of the C(CN)2 units is disordered over two sets of atomic sites having occupancies 0.75 (2) and 0.25 (2). The cations are linked by two independent C-H⋯Cl hydrogen bonds to form a sheet of R22(14) and R42(24) rings.

Coordination compounds of a hydrazone derivative with Co(iii), Ni(ii), Cu(ii) and Zn(ii): synthesis, characterization, reactivity assessment and biological evaluation

Increasing inhibitory effect of Zn-Hp2DAP < Hp2DAP < Co-Hp2DAP on ABC transporter MDR1 drug efflux pump.