Structural studies of molecular-based nanoporous materials. Novel networks of silver(I) cations assembled with the polydentate N-donor bases hexamethylenetetramine and 1,3,5-triazine

Abstract

Novel polymeric materials have been isolated from the reactions of silver(i) salts of poorly coordinating anions with the polydentate bases hexamethylenetetramine (hmt) and 1,3,5-triazine (trz), the one-dimensional polymer[Ag(hmt)] SbF ₆ H ₂ O 1, and the three-dimensional networked compounds [Ag ₁₁ (hmt) ₆ ][PF ₆ ] ₁₁ 14H ₂ O 2 and [Ag ₆ (trz) ₈ ][BF ₄ ] ₆ H ₂ O 3, characterized by single-crystal X-ray analysis. Compound 1is monoclinic, space groupP2 ₁ /n, a=14.252(4), b=11.061(8), c=16.450(8) Å, β=90.17(3)°. The structure contains a novel type of ribbon formed by hexagonal meshes of alternate Ag ^I ions and hmt molecules. The water molecules coordinated to the silver ions form hydrogen bonds which generate a three-dimensional network of unprecedented topology. Crystals of 2 are monoclinic, space group I2, a=19.552(6), b=10.856(6), c=25.749(11) Å, β=92.83(3)°. It consists of an open three-dimensional network of complex topology with all the hmt molecules tetraconnected. Out of the eleven independent Ag ^I ions per formula unit, nine are biconnnected and two triconnected to the hmt bases. The large channels in the network contain many water molecules. Compound 3 is monoclinic, space group P2 ₁ /c, a=12.535(8), b=29.517(8), c=14.704(6) Å, β=93.95(4)°. The structure contains six independent Ag ions and eight independent triazine molecules, which display varied connectivities to give a puzzling three-dimensional network.