Effect of Different Carboxylates on a Series of Ag(I) Coordination Compounds with Benzoguanamine Ligand

The ultrasonic reactions of Ag2O with benzoguanamine and ancillary carboxylate ligands under the ammoniacal condition gave eight new coordination compounds (CCs), namely, [Ag-4(bga)(6)(mal)(2)] (1), [Ag-4(bga)(6)(mlc)(2)] (2), [Ag(bga)(2)(tpa)(0.5)](n) (3), {[Ag(bga)(suc)(0.5)]center dot C2H5OH}(n) (4), {[Ag(bga)(Pta)(0.5)]center dot CH3OH}(n) (5), {[Ag(bga)(ox)(0.5)]center dot C2H5OH center dot H2O}(n) (6), {[Ag-2(bga)(2)(dnb)(2)]center dot DMF}(n) (7), and [Ag-2(bga)(2)(pma)(0.5)(H2O)](n) (8) (bga = benzoguanamine, H(2)mal = malonic acid, H(2)mlc = maleic acid, H(2)tpa = terephthalic acid, H(2)suc = succinic acid, H(2)pta = phthalic acid, H(2)ox = oxalic acid, Hdnb = 3,5-dinitrobenzoic acid, H(4)pma = pyromellitic acid, and DMF = N,N'-dimethylformamide). All CCs have been characterized by elemental analyses, IR spectra, and single-crystal X-ray diffraction. Compounds 1 and 2 are OD discrete molecules and contain centrosymmetric [Ag-2(mal)](2) and [Ag-2(mlc)](2) units, respectively, which are extended to ID supramolecular chains through intermolecule N-H center dot center dot center dot N complementary hydrogen bonds. Compounds 3 and 4 contain similar ID [Ag-2(tpa)](n) and [Ag-2(suc)](n) infinite chains incorporating monodentate bga ligand as an ornament. It is noteworthy that the Ag center dot center dot center dot Ag interaction was exclusively observed in the ID chain of compound 4, which may be caused by different coordination environments of the Ag(I) center between 3 and 4. The Ag center dot center dot center dot pi interactions further extend the ID chains into 2D sheet in 4. In 5 and 6, the mu(2)-bga ligands link Ag(I) ions to form ID helical chains, which are further extended by mu(2)-dicarboxylate to 2D 6(3)-hcb net incorporating different dimensions of hexagonal grids. Compound 7 is a ID chain containing [Ag-2(dnb)(2)] subunits, to which the monodentate and bidentate bga ligands as well as DMF coordinate. Compound 8 is a 2D sheet structure incorporating mu(6)-eta(1):eta(1):eta(1):eta(1):eta(1):eta(0):eta(1):eta(0) pma, monodentate and bidentate bga ligands. The results show that the structural diversity (0D-2D) of the CCs is mainly attributed to the usage of diverse ancillary carboxylate ligands as well as diverse coordination modes of bga ligand. Moreover, the photoluminescence properties of the CCs 1-6 were also investigated in the solid state at room temperature.