Poly[bis(mu-4-benzoyl-1-isonicotinoylthiosemicarbazide-kappa2N:S)dichloridocadmium(II)]

Syntheses and structures of discrete copper(II) and cadmium(II) supramolecular complexes based on 1,4-diacylthiosemicarbazone ligands

Thiosemicarbazides and their metal complexes have attracted considerable interest because of their biological activities and their flexibility, which allows the ligands to bend and rotate freely to accommodate the coordination geometries of various metal centres. Discrete copper(II) and cadmium(II) complexes have been prepared by crystallization of N-[2-(2-hydroxybenzoyl)hydrazinecarbonothioyl]propanamide (H3L) with Cu(CH3COO)2 or Cd(NO3)2 in a dimethylformamide/methanol mixed-solvent system at room temperature, affording the complexes di-μ-acetato-bis{μ4-1-[(2-oxidophenyl)carbonyl]-2-(propanamidomethanethioyl)hydrazine-1,2-diido}tetracopper(II) dimethylformamide disolvate, [Cu4(C11H10N3O3S)2(C2H3O2)2]·2C3H7NO, (I), and bis{μ2-[(2-hydroxyphenyl)formamido](propanamidomethanethioyl)azanido}bis[(4,4'-bipyridine)nitratocadmium(II)] dihydrate, [Cd2(C11H12N3O3S)2(NO3)2(C10H8N2)2]·2H2O, (II). Complex (I) consists of four Cu(II) cations, two μ4-bridging trianionic ligands and two μ2-bridging acetate ligands, while complex (II) is composed of two Cd(II) cations, two μ2-bridging monoanionic ligands, two nitrate ligands and two 4,4'-bipyridine ligands. These discrete complexes are connected by hydrogen bonds and van der Waals interactions to form a three-dimensional supramolecular architecture. Compared with (I), the phenolic hydroxy group and hydrazide N atom of the thiosemicarbazide ligand of (II) are not involved in coordination and lead to a binuclear Cd(II) complex. This different coordination mode may be attributed to the larger ionic radius of the Cd(II) ion compared with the Cu(II) ion.

Poly[[(μ2-4,4'-bipyridyl-κ(2) N:N')bis-{μ2-N-[2-(2-hy-droxy-benzo-yl)carbamo-thio-yl]acetamidato-κ(4) O,N,O':S}bis-(nitrato-κ(2) O,O')dicadmium] di-methyl-formamide tetra-solvate]

The asymmetric unit of the title complex, {[Cd₂(C₁₀H₁₀N₃O₃S)₂(C₁₀H₈N₂)(NO₃)₂]·4C₃H₇NO}_n, consists of one Cd^II cation, one N-[2-(2-hy­droxy­benzo­yl)carbamo­thio­yl]acetamidate ligand, half a 4,4′-bipyridyl ligand, one coordinating nitrate anion and two di­methyl­formamide solvent mol­ecules of crystallization. The bipyridine ligand is completed by inversion symmetry. The metal cation exhibits a distorted penta­gonal–bipyramidal coordination geometry provided by two O and one N atoms of the thio­semicarbazide ligand, two O atoms of the nitrate anion, one S atom of a neighbouring thio­semicarbazide ligand and one 4,4′-bi­pyridine N atom. The bridging role of the thio­semicarbazide ligand through the S atom leads to centrosymmetric binuclear units, which are further linked by 4,4′-bi­pyridine units, forming polymeric chains extending along the b-axis direction. An intra­molecular N—H⋯O hydrogen bond occurs. The crystal structure also features N—H⋯O and O—H⋯O hydrogen bonds, leading to the formation of a three-dimensional network.