Synthesis and structure of coordination polymers of Ag(I) with isomeric (aminomethyl)pyridines. Formation of a novel circular helicate and 2-D networks via Ag⋯Ag contacts and coordination shell expansion under anion control

Abstract

Reaction between Ag(I) salts and the three isomers of (aminomethyl)pyridines, viz., 2-amp, 3-amp, and 4-amp, lead to either discrete or polymeric (1-D and 2-D) structures influenced by anions and closed shell Ag⋯Ag contacts. Characterization data for Ag(2-amp)BF4 (1) follow: monoclinic, space group C2/c, with a = 16.788(2) Å, b = 11.5719(6) Å, c = 11.3864(7) Å, β = 123.671(8)°, and Z = 8. For Ag2(2-amp)3(PF6)2 (2): monoclinic, space group P21/a, with a = 10.029(7) Å, b = 20.291(12) Å, c = 13.907(6) Å, β = 95.38(5)°, and Z = 4. For Ag 2(3-amp)3(PF6)2 (4): triclinic, space group P1, with a = 10.4482(7) Å, β = 11.1468(9) Å, c = 12.2720(11) Å, α = 81.018(7)°, β = 80.668(6)°, γ = 80.977(6)°, and Z= 2. For Ag(4-amp)BF4·0.75CH 3CN (5): orthorhombic, space group C2221, with a = 9.272(2) Å, b = 16.164(12) Å, c = 27.851(2) Å, and Z = 8. For Ag(4-amp)PF6 (6): monoclinic, space group P21/m, with a = 5.2089(7) Å, b = 14.3950(17) Å, c = 7.0149(14) Å, β = 96.538(14) Å, β = 96.538(14)°, and Z = 2. While Ag(I) is 2-coordinate in 1, 5 and 6, it shows 3-coordination in 2 and 4. Compound 1 consists of a 1-D polymeric cation chain with interchain Ag⋯Ag contacts and the anions sitting on the edges of the chains. The dication in 2 is held in the form of a circular helicate by closed shell Ag⋯Ag interactions. Compound 4 generates a 2-D network with channels big enough to accommodate the anions. Compound 5 is a 2-D chiral network of chains connected by Ag⋯Ag contacts. Compound 6 shows a simple 1-D chain structure with an alternating arrangement of cationic chains and anions.