Cai-Xia Meng

A versatile V-shaped tetracarboxylate building block for constructing mixed-ligand Co(II) and Mn(II) complexes incorporating various N-donor co-ligands

Hydrothermal reactions of 3,3′,4,4′-diphenylsulfonetetracarboxylic dianhydride with Co(II) or Mn(II) acetate and systematically varied N-donor co-ligands leads to the formation of a series of supramolecular complexes, namely, [Co(H2dpstc)(trpy)·H2O] (1), [Co2(dpstc)(phen)2·4H2O]·2H2O (2), [Mn2(dpstc) (phen)2·5H2O] (3), [Mn2(dpstc)(bipy)2·3H2O]·H2O (4) and [Mn2(dpstc)(bpe)2·2H2O]·2H2O (5), where dpstc = 3,3′,4,4′-diphenylsulfonetetracarboxylate, trpy = 2,2′:6′,2′′-terpyridine, phen = 1,10-phenthro- line, bipy = 2,2′-bipyridine and bpe = 1,2-di(4-pyridyl)ethylene. Single-crystal X-ray analysis reveals that complex 1 shows a simple 1D linear array, 2 exhibits a unique 1D chain with pendant arms, and 3 displays a binuclear core. Interestingly, such 1D or dimeric coordination motifs in 1–3 hold the recognition sites of hydrogen bonding and/or π–π stacking, which result in the extended 3D architectures. In contrast, complexes 4 and 5 represent a 2D (4,4) layer and a 3D 4-connected (64·82) framework, respectively. By careful inspection of the structures for 1–5, it is clear that the tetracarboxylate with different coordination modes as well as the auxiliary N-donor ligands play a critical role in determining the coordination array and further packing modes of the final 3D lattice architectures. Magnetic susceptibilities of complexes 1–5 reveals the weak antiferromagnetic exchange interactions between the adjacent metal centers and their thermal stability has also been studied.

(4, 5)-Connected 3D Supramolecular Framework Based on 1D Tube-Shaped Coordination Armed-Chains [Mn(4,4′-bipy)(OAc)2]n

A novel manganese(II) compound, namely, [Mn(4,4′-bipy)(OAc)2] n (1) (4,4′-bipy = 4,4′-bipyridine), has been hydrothermally synthesized and characterized. Single crystal X-ray diffraction reveals that it crystallizes in triclinic, P_ space group with a = 8.043 (4) Å, b = 9.319 (5) Å, c = 10.769 (6) Å, α = 109.342 (5)°, β = 99.823 (7)°, γ = 101.808 (7), V = 720.2(7) Å3, C24H14MnN2O4, Mr = 329.21, Dc = 1.518 g·cm−3, Z = 1, F(000) = 338, the final R = 0.0485 and wR = 0.1028 for 3754 observed reflections [I > 2σ]. In 1, the cyclic dimeric metal acetate secondary building units are linked through 4,4′-bipyridine to yield 1D tube-shaped infinite armed-chains, which are further extended to a 3D supramolecular network with (4,5)-connected (44·62)(4465·8) topology through R2 1(5) and R2 1(7) C─H─O hydrogen bonds. Variable-temperature magnetic susceptibility measurements indicate weak antiferromagnetic exchange interactions between adjacent Mn2 + centers.

Aqua­(2,2′-bipyridine-κ2N,N′)[2-(3-thien­yl)malonato-κ2O,O′]zinc(II) dihydrate

In the crystal structure of the title compound, [Zn(C7H4O4S)(C10H8N2)(H2O)]·2H2O, the ZnII ion assumes a trigonal–bipyramidal coordination geometry completed by two N atoms from a 2,2′-bipyridine ligand, two O atoms from a 2-(3-thienyl)malonate anion and a water molecule. The S atom of the 2-(3-thienyl)malonate ligand is disordered over two sites with an occupancy ratio of 0.701 (5):0.299 (5). Intermolecular O—H⋯O hydrogen bonding is present in the crystal structure.

3-Carboxy­pyrazino[2,3-f][1,10]phenanthrolin-9-ium-2-carboxyl­ate

In the title zwitterionic compound, C16H8N4O4, the dihedral angle between the carboxyl and carboxylate groups is 72.14 (2)°. In the crystal, molecules are linked by strong intermolecular O—H⋯O− and N+—H⋯O− hydrogen bonds into double chains extended along [001]. These chains are additionally stabilized by π–π stacking interactions between the pyridine and benzene rings [centroid–centroid distance = 3.5542 (8) Å].