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Two new two-dimensional (2D) layer coordination polymers--namely, [Cd(L)2]n (1) and [Co(L)2(H2O)]n (2)--were synthesized by the reaction of corresponding metal salts with 3-(1H-imidazol-4-yl)benzoic acid (HL) incorporating 4-imidazolyl and carboxylate functional groups, and characterized by single-crystal X-ray diffraction, elemental analysis, IR spectroscopy, and powder X-ray diffraction (PXRD). Complex 1 is a 2D network with (4, 4) topology, while 2 is a typical 6³-hcb topology net. Complex 1 exhibits intense light blue emission in the solid state at room temperature. [ABSTRACT FROM AUTHOR]

A new 1D chained Ca(II) coordination polymer--namely, [CaL2(H2O)2]n (HL = 3,5-bis(4-pyridylmethoxy)benzoic acid)--was synthesized though the reaction of Ca(ClO4)2.4H2O, 3,5-bis(4-pyridylmethoxy)benzoic acid and NaOH in H2O/CH3CH2OH (v:v = 1:2) solution. Its structure was determined by elemental analysis, infrared spectrum, and single-crystal XRD. Structural analyses show that each Ca(II) ion is eight-coordinated by six oxygen atoms of four 3,5-bis(4-pyridylmethoxy)benzoate ligands and two oxygen atoms of two coordinated H2O molecules to form a square-antiprismatic CaO8 polyhedron. The Ca(II) complex displays a 1D chained structure constructed by the bridging effect of the bidentate carboxyl group of 3,5-bis(4-pyridylmethoxy)benzoate ligand. The catalytic activity of the Ca-complex was tested for the preparation of propargylamine in the A³ coupling reaction. [ABSTRACT FROM AUTHOR]

The selective preparation, structural and spectroscopic study of two new rhenium cluster complexes trans-[Re6S8(bpy)4(CN)2] and trans-[Re6S8(bpy)2(CN)4]2− (bpy = 4,4′-bipyridine) obtained by reactions of corresponding hexarhenium cyanohalides with molten bpy are reported. The complexes were crystallized as solvates, displaying supramolecular structures based on cluster units linked by numerous weak interactions with bpy molecules. The molecular compound trans-[Re6S8(bpy)4(CN)2] (1) is insoluble in water and common organic solvents, while the ionic compound trans-Cs1.7K0.3[Re6S8(bpy)2(CN)4] (2) is somewhat soluble in DMSO, DMF and N-methylpyrrolidone. The presence of the redox-active ligand bpy leads to the occurrence of multi-electron reduction transitions in a solution of 2 at moderate potential values. The ambidentate CN− ligand is the secondary functional group, which has potential for the synthesis of coordination polymers based on the new cluster complexes. In addition, both new compounds show a weak red luminescence, which is characteristic of complexes with a {Re6S8}2+ cluster core. [ABSTRACT FROM AUTHOR]

The synthesis of amide-based molecules, possessing pre-organized structures, has received significant attention due to their potential applications as molecular receptors and as components of nanomaterials. In this study, four extended tetraamide ligands incorporating ethylene and propylene spacers, namely 1,2-bis[N,N′-6-(3-pyridylmethylamido)pyridyl-2-carboxyamido]ethane (L1), 1,2-bis[N,N′-6-(4-pyridylmethylamido)pyridyl-2-carboxyamido]ethane (L2), 1,2-bis[N,N′-6-(3-pyridylmethylamido)pyridyl-2-carboxyamido]propane (L3) and 1,2-bis[N,N′-6-(4-pyridylmethylamido)pyridyl-2-carboxyamido]propane (L4), were successfully synthesized. Further, reaction of L2 and L4, incorporating pendant 4-pyridyl donors as the metal coordinating sites, with cadmium salts, produced two close-packed one-dimensional coordination polymers, {[Cd3(L2)4(H2O)10](NO3)6·12H2O·CH3OH}n and {[Cd(SO4)(L4)(H2O)2]·4H2O·CH3OH}n. X-ray crystallography reveals that the flexible tetraamide ligands fold upon themselves in the coordination polymer structure. As a consequence, the anion pocket in {[Cd(SO4)(L4)(H2O)2]·4H2O·CH3OH}n incorporating the ligand with the propylene spacer was blocked from encapsulating charge-balancing anions, which were involved in bridging the di-cadmium units. Interestingly, a strong interaction between the 2,6-pyridine dicarboxamide moiety with the nitrate anions was found in {[Cd3(L2)4(H2O)10](NO3)6·12H2O·CH3OH}n, showing potential for materials made from these ligands to serve as anion receptors. [ABSTRACT FROM AUTHOR]

A relatively unexplored synthetic route in redox-active Mn(II/III) coordination chemistry has been employed toward the preparation of a new mixed-valence MnII/III 1-D linear chain from the reaction of [MnIII(sacb)2]− precursor with a MnII source, where sacbH2 is the Schiff base ligand N-salicylidene-2-amino-5-chlorobenzoic acid. The mononuclear (Pr2NH2)[MnIII(sacb)2] (1) compound was obtained in excellent yields (>85%) from the 1:2:3 reaction of Mn(O2CMe)2∙4H2O, sacbH2 and Pr2NH, respectively. In 1, the two doubly deprotonated sacb2− ligands act as Ocarboxylate,Nimine,Ophenoxide-tridentate chelates, while the second carboxylate O atom of sacb2− is dangling and H-bonded to the Pr2NH2+ countercation. Complex 1 was subsequently used as a 'ligand' to react stoichiometrically with the 'metal' Mn(NO3)2∙4H2O, thus leading to the 1-D coordination polymer {[MnIIMnIII(sacb)2(H2O)2(MeOH)2](NO3)}n (2) in good yields (~50%). The removal of Pr2NH2+ from the vicinity of the [MnIII(sacb)2]− metalloligand has rendered possible (vide infra) the coordination of the second Ocarboxylate of sacb2− to neighboring {MnII(H2O)2(MeOH)2}2+ units, and consequently the formation of the 1-D polymer 2. Direct-current (dc) magnetic susceptibility studies revealed the presence of very weak antiferromagnetic exchange interactions between alternating MnIII and MnII atoms with a coupling constant of J = −0.08 cm−1 for g = 2.00. The combined results demonstrate the potential of the 'metal complexes as ligands' approach to yield new mixed-valence Mn(II/III) coordination polymers with interesting structural motifs and physicochemical properties. [ABSTRACT FROM AUTHOR]