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

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journal contribution
posted on 06.10.2008, 00:00 by Blanca R. Manzano, Félix A. Jalón, M. Laura Soriano, M. Carmen Carrión, M. Pilar Carranza, Kurt Mereiter, Ana M. Rodríguez, Antonio de la Hoz, Ana Sánchez-Migallón
New coordination polymers have been obtained by the self-assembly of silver salts AgX (X = BF4, PF6, CF3SO3) and 2,4-diamino-6-R-1,3,5-triazines L (R = phenyl and p-tolyl) of formulas AgLX (16). A complex of different stoichiometry, [Ag3L2(H2O)(acetone)2](BF4)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 = BF4 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 CF3SO3 (OTf). When R = phenyl, sheets are formed which consist of [Ag2(OTf)2L2] 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 κ2O2-O and κ1O2-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 BF4 group 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.