Supramolecular architecture of cadmium (II)–terephthalate complexes having a tridentate or tetradentate Schiff base as blocking coligand

Two new cadmium (II)–terephthalate complexes, _∞¹{[Cd₂(μ-terephthalate)₂(L¹)₂]•9H₂O} (1) and [{Cd(H₂O)(L²)}₂(μ-terephthalate)](terephthalate) • 10H₂O (2), where L¹ = (E)-N¹,N¹-diethyl-N²-(1-(pyridin-2-yl)ethylidene)ethane-1,2-diamine; L² = N,N ′-bis-(1-pyridin-2-yl-ethylidene)-ethane-1,2-diamine; terephthalate = benzene-1,4-dicarboxylate (^-O₂C-C₆H₄-CO₂^-) have been synthesized by a conventional solution method. Characterization by single crystal X-ray crystallography shows that compound 1 is composed of 1-D polymeric zig-zag chains with distorted pentagonal-bipyramidal cadmium centers. Compound 2 consists of centrosymmetric dinuclear complexes with a distorted pentagonal-bipyramidal cadmium center in which one terephthalate ligand bridges the metal centres and another terephthalate anion with water of crystallization forms a H-bonding network

Synthesis, structure and bonding of cadmium (II) thiocyanate systems featuring nitrogen based ligands of different denticity

Complexes catena-[di(4-amino-pyridine)di(μ-S,N-thiocyanato)cadmium(II)], 1∞[cd(μ-SCN)2 (L1)2], (1) catena-[{(1-pyridine-2-yl-ethylene)-hydrazine}di(μ-S,N-thiocyanato)cadmium(II)], 1∞[cd(μ-SCN)2 (L2) (2) and di-μ-S,N-thiocyanatobis{(N,N-diethyl-N′-(1-pyridine-2-yl-ethylidene)-ethane-1,2-diamine)(N-thiocyanato)cadmium(II)}, [Cd(NCS)(μ-SCN)(L3)]2 (3) have been synthesized by reacting cadmium acetate/NH4SCN with 4-amino-pyridine (L1), C5H4N–C(CH3) = NNH2 (L2) and C5H4N–C(CH3) = N–CH2–CH2–N(C2H5)2 (L3), respectively, in methanol. Characterization by single-crystal X-ray crystallography shows that in compounds 1 and 2 the cadmium atoms have a 4N2S-hexa-coordination sphere, exhibiting pseudo-octahedral geometry. The cadmium atoms are bridged by two thiocyanate ions generating 1-D polymeric chains. Compound 3 is a centrosymmetric dimeric complex, with the cadmium atom pseudo octahedrally surrounded by a 5N1S coordination sphere. In compound 1 the crystal packing is controlled mainly by interchain N–H⋯N and C–H⋯π interactions between the aminopyridine moieties, whereas in complexes 2 and 3 π-stacking interactions between the pyridyl planes stabilize the interchain or intermolecular packing, respectively. Thiocyanate and pyridylimine chelation to metal center is also scrutinized with EHMO analysis