Mononuclear, dinuclear, hexanuclear, and one-dimensional polymeric silver complexes having ligand-supported and unsupported argentophilic interactions stabilized by pincer-like 2,6-bis(5-pyrazolyl) pyridine ligands

摘要

The mononuclear complexes [Ag(H2L1)(Py)(2)](NO3)center dot H2O (1, H2L1 = 2,6-bis(5-methyl-1H-pyrazol-3-yl) pyridine) and [Ag(NO3)(L-2)] (2, L-2 =2,6-bis(5-methyl-1-isopropyl-1H-pyrazol-3-yl)pyridine), dinuclear complex [Ag-2(H2L3)(2)(HL4)(2)] (3, H2L3 = 2,6-bis(5-phenyl-1H-pyrazol-3-yl) pyridine, HL4 = 6-(5-phenyl-1H-pyrazolyl-3-yl) picolinate), one-dimensional polymer {[Ag-2(H2L1)(2)](NO3)(2)center dot H2O}(n) (4), and hexanuclear clusters [Ag-6(HL1)(4)](X)(2) ( X = NO3-, 5; BF4-, 6; ClO4-, 7) stabilized by pincer-like bispyrazolyl ligands have been prepared and characterized using H-1 NMR spectroscopy, elemental analysis, IR spectroscopy, luminescence spectroscopy and X-ray diffraction. In complex 3, there is a ligand unsupported Ag-Ag bond between the two silver atoms. Complex 4 displays a one-dimensional polymer consisting of an infinite Ag-Ag chain and every two adjacent silver ions are bridged by an H2L1 ligand. Complexes 5 and 7 have the same Ag6 cores in which six silver atoms are held together by four HL1 and five Ag-Ag bonds, while complex 6 was held together by six Ag-Ag bonds. The silver-silver distances in these complexes are found in the range of 2.874(1)-3.333( 2) angstrom for ligand supported, and 3.040(1) angstrom for ligand unsupported Ag-Ag bonds, respectively. Complexes 3-7 are strongly luminescent due to either intraligand or metal-ligand charge transfer processes.