Anion-Dependent Self-Assembly of Silver(I) and Diaminotriazines to Coordination Polymers: Non-Covalent Bonds and Role Interchange between Silver and Hydrogen Bonds (original) (raw)

2008, Inorganic Chemistry

New coordination polymers have been obtained by the self-assembly of silver salts AgX (X ) BF 4 , PF 6 , CF 3 SO 3 ) and 2,4-diamino-6-R-1,3,5-triazines L (R ) phenyl and p-tolyl) of formulas AgLX (1-6). A complex of different stoichiometry, [Ag 3 L 2 (H 2 O)(acetone) 2 ](BF 4 ) 3 , 7 (R ) phenyl), has also been synthesized. The three-dimensional structures of five compounds have been determined by X-ray diffraction studies. For the AgLX complexes, when X ) BF 4 and R ) phenyl or p-tolyl, chiral chains with alternating Ag and L are formed. The chains are cross-linked by the counteranions in a three-dimensional fashion through hydrogen bonds and weak Ag · · · F interactions giving rise to a structure with solvent-filled channels. Different and more compact structures have been found when the counteranion is CF 3 SO 3 (OTf). When R ) phenyl, sheets are formed which consist of [Ag 2 (OTf) 2 L 2 ] units with double triflate bridges and which contain columns of π-π stacked arenes. Hydrogen bonds connect the sheets. When AgOTf is used and R is p-tolyl, a different and unusual ladderlike structure is obtained in which the rungs are double asymmetric bridges consisting of the triflate groups bonded to Ag in κ 2 O,µ 2 -O and κ 1 O,µ 2 -O fashion. The ladders are parallel to each other and are mutually linked by N-H · · · N hydrogen bonds to give a 3D architecture. A very similar ladderlike structure has been found for 7 but with a water molecule and a BF 4group acting as bridges. The role played by the hydrogen bonds in complex 6 to form the 3-D structure is played in 7 by [Ag(acetone) 2 ] fragments. The noncovalent interactions play an important role in the different solid-state 3D structures. The behavior of the new derivatives in solution has also been analyzed. A new species has been detected at low temperatures, and this exhibits restricted rotation of the phenyl ring. Moler, D. B.; Li, H.; Chen, B.; Reineke, T. M.; O'Keeffe, M.; Yagi, O. M. Acc. Chem. Res. 2001, 34, 319-330. (d) Ockwig, N. W.; Delgado-Friedrichs, O.; O'Keeffe, M.; Yagi, O. M.