Molecular and supramolecular architectures of silver(I) and copper(I) complexes of 2,6-pyridinediylbis(2-pyridinyl)methanone

Structural Study of Silver(I) Sulfonate Complexes with Pyrazine Derivatives

In this Article, 11 silver complexes, namely, [Ag(L1)(2-Pyr)(H2O)] (1), Ag(L1)(2,3-Pyr) (2), [Ag2(L1)2(2Et,3Me-Pyr)2(H2O)] (3), [Ag(2,6-Pyr)](L1).1.5H2O (4), Ag(L1)(2,5-Pyr) (5), [Ag(H2O)2](L2).H2O (6), [Ag(L2)(2-Pyr)] (7), [Ag(L2)(2,3-Pyr)].1.5H2O (8), [Ag(L2)(2Et,3Me-Pyr)].2H2O (9), [Ag2(L2)(2,6-Pyr)(H2O)2](L2).H2O (10) and [Ag(L2)(2,5-Pyr)].H2O (11) (2-Pyr=2-methylpyrazine; 2,3-Pyr=2,3-dimethylpyrazine; 2Et,3Me-Pyr=2-ethyl-3-methylpyrazine; 2,6-Pyr=2,6-dimethylpyrazine; 2,5-Pyr=2,5-dimethylpyrazine; L1=p-aminobenzenesulfonate anion and L2=6-amino-1-naphthalenesulfonate anion), have been synthesized and characterized by elemental analyses, IR spectroscopy, and X-ray crystallography. In 1, 3, and 4, Ag(I) centers are linked by bridging pyrazine ligands to form one-dimensional chains, whereas compound 2 shows a double-chain structure through weak Ag-C interactions. The structure analyses show that both 5 and 11 form two-dimensional networks composed of 26-membered metallocycles. Unexpectedly, compounds 6 and 10 show discrete structures. In compound 7, silver(I) centers are bridged by sulfonate anions to form a polymeric helical structure, and the 2-Pyr molecule acts as a monodentate ligand. Compounds 8 and 9 show hinged chain structures containing 14-membered rings, and these chains interlace with each other to generate unique three-dimensional structures. These results indicate that the substituting groups and the substituting sites of pyrazine derivatives play an important role in the framework formation of silver complexes. Additionally, the luminescent properties of these compounds are also discussed.

An “S”-shaped pentanuclear CuII cluster derived from the metal-assisted hydrolysis of pyCOpyCOpy: structural, magnetic and spectroscopic studies

Reaction of [Cu2(O2CMe)4(H2O)2] with 2,6-di-(2-pyridylcarbonyl)-pyridine (pyCOpyCOpy or dpcp) in MeCN-H2O 10:1, led to the pentanuclear copper(II) complex [Cu5(O2CMe)6{pyC(O)(OH)pyC(O)(OH)py}2] () which crystallizes in the triclinic P1 space group. The copper(II) atoms are arranged in an "S"-shaped configuration, and are bridged by the doubly deprotonated bis(gem-diol) form of the ligand, pyC(O)(OH)pyC(O)(OH)py2-. Magnetic susceptibility data indicate the interplay of both ferro- and antiferromagnetic intramolecular interactions stabilizing an S=3/2 ground state. Fitting of the data according to a next-nearest-neighbour model {H=-[J1(S1S2+S1'S2')+J2(S2S3+S3'S2')+J3(S1S3+S3'S1')+J4(S2S2')]} yields exchange coupling constants J1=+39.7 cm(-1), J2=-15.9 cm(-1), J3=-8.3 cm(-1) and J4=+4.3 cm(-1), leading to an S=3/2 ground state. X-Band EPR spectroscopy indicates a zero-field splitting of the ground state with |D3/2|=0.38 cm(-1).