New Ag(I)-Containing Coordination Polymers Generated from Multidentate Schiff-Base Ligands

The coordination chemistry of the multidentate Schiff-base ligands 2,5-bis(3-methylpyrazinyl)-3,4-diaza-2,4-hexadiene
(L5) and 2,5-bis(pyrazinyl)-3,4-diaza-2,4-hexadiene (L6) with inorganic Ag(I) salts has been investigated. Six new
Ag(I)-coordination polymers were prepared by solution reactions and fully characterized by infrared spectroscopy,
elemental analysis, thermogravimetric analysis, and single-crystal X-ray diffraction. [Ag(L5)]ClO4·0.5CH3OH (1,
orthorhombic, Fdd2; a = 20.0896(11) Å, b = 48.224(3) Å, c = 7.8432(4) Å, Z = 16), [Ag(L5)]PF6·0.5CH3OH (2,
orthorhombic, Fdd2; a = 20.7255(11) Å, b = 46.166(2) Å, c = 8.4332(4) Å, Z = 16), [Ag(L5)]SbF6·0.5CH3OH (3,
orthorhombic, Fdd2; a = 21.5481(11) Å, b = 45.196(2) Å, c = 8.7331(4) Å, Z = 16), and [Ag(L5)](BF4)·0.5CH3OH (4, orthorhombic, Fdd2; a = 19.8897(11) Å, b = 48.358(3) Å, c = 7.7491(5) Å, Z = 16) were obtained by
combination of L5 with AgClO4·xH2O, AgPF6, AgSbF6, and AgBF4, respectively, in a methylene chloride/methanol
mixed solvent system. Compounds 1−4 are isostructural and feature noninterpentrating three-dimensional zeolite-like networks. [Ag4(L6)4](PF6)4·CHCl3 (5, tetragonal, P4̄c2; a = 16.1067(3) Å, b = 16.1067(3) Å, c = 14.4935(5)
Å, Z = 2) was generated from the reaction of L6 with AgPF6 in a chloroform/ethanol mixed solvent system. It
forms with a unique one-dimensional nanometer-tube that can be considered a new polymeric motif based on the
{AgN5} coordination sphere. The tubes are square with crystallographic dimensions of 10.3 × 10.0 Å. The tubes
are further linked together through weak interpolymer C−H···F hydrogen bonding interactions into a novel H-bonded
three-dimensional network containing square tubes, in which uncoordinated PF6- counterions and chloroform guest
molecules are located. Compound 6 ([Ag(μ-C6H6N2O)](SO3CF3), monoclinic, P21/c; a = 12.3435(6) Å, b = 20.3548(10) Å, c = 9.0861(5) Å, Z = 8) was obtained by combination of AgSO3CF3 and L6 in a methylene chloride/benzene mixed solvent system. In 6, 2-acetylpyrazine, which was generated from the hydrolysis reaction of L6 in
the presence of CF3SO3- and a small quantity of water in solvent, chelates the Ag(I) centers through the carbonyl
O-donor, and the vicinal pyrazine N-donor, furthermore, uses the para-N atoms to link other Ag(I) centers into
one-dimensional zigzag chains. The triflate anions link the chains into a three-dimensional network by somewhat
long Ag···O contacts.