Influence of the Anion on the Structure of Bis(methylthio)methane Supramolecular Coordination Complexes Mohamed Osman Awaleh, Antonella Badia, and Franc ¸ ois Brisse* De ´ partement de Chimie, UniVersite ´ de Montre ´ al, C. P. 6128, Succursale Centre-Ville, Montre ´ al, Que ´ bec H3C 3J7, Canada ReceiVed March 17, 2006; ReVised Manuscript ReceiVed July 14, 2006 ABSTRACT: A series of coordination networks has been synthesized by the self-assembly of the small bis(methylthio)methane building block and AgX (X ) NO 3 - (1), ClO 4 - (2, 3), p-TsO - (4), CF 3 COO - (5), CF 3 CF 2 CF 2 COO - (6), CF 3 SO 3 - (7), C 6 H 5 COO - (8), CH 3 SO 3 - (9), and HOOCCF 2 CF 2 COO - (10)) in order to rationalize the effect of the size of the anions and the ligands upon the structure adopted by the supramolecular coordination network. In complexes 1-7, each silver(I) is coordinated with sulfur atoms from three different ligands. They form very similar two-dimensional solid-state organizations. The structures consist of layers, made up of Ag and bis(methylthio)methane ligands only, in which the anions complete the tetrahedral coordination of the silver atoms. Upon closer inspection, the neutral 2D networks may be sorted into two distinct classes. Group 1 incorporates the smallest anions, NO 3 - and ClO 4 - , whereas the more elongated anions, p-TsO - , CF 3 COO - , CF 3 CF 2 CF 2 COO - , and CF 3 SO 3 - , are found in group 2. The main difference between these groups is in the organization of the neutral layers. In group 1, the repeat unit consists of a large 14-membered metallomacrocycle, whereas in group 2, the metallomacrocycle consists of 10-membered rings. The two polymorphs of the perchlorate complexes are structurally comparable. Dimeric units are the basis for the other three complexes. In benzoate 8, the dimers are formed with two anions. They are linked by ligand molecules to form a 1D polymeric chain that adopts a distorted hexagonal packing. The silver atoms have a distorted triangular bipyramidal coordination and the Ag‚‚‚Ag distance is 2.911 Å. In complex 9, two ligands each bridge a pair of silver atoms to form a dimer (Ag‚‚‚Ag ) 3.243 Å). A neutral 1D coordination polymer is obtained when anions connect, in a dibridging mode, the silver atoms of adjacent dimers [Ag(CH 3 SCH 2 SCH 3 )] 2 . Weak hydrogen interactions between chains result in a 3D network. The silver coordination is triangular bipyramidal. Complex 10 is also a 1D coordination polymer with a centrosymmetric dimer. Two ligands and two anions are coordinated to the silver atoms. The Ag‚‚‚Ag contact is 3.067 Å. A 1D coordination polymer is obtained through H-bonding between carboxylate groups. The stoichiometries of the complexes are independent of the initial metal-to-ligand ratios and are not influenced by the solvent of recrystallization. Introduction Metal-organic coordination polymers are attracting a great deal of attention because of their potential as functional materials. 1 In metal-organic crystal engineering, one takes advantage of the coordinating ability of metal centers and organic ligands in order to build new coordination polymers. The main goal in metal-organic crystal engineering is to predict the topology of supramolecular architectures in order to synthesize extended solid-state materials with desired properties. However, there still remain many obstacles to overcome before the synthesis of coordination polymers with a desired topology is possible. Many parameters are involved in the formation of the metal-organic framework (MOF), such as the metal and its coordinating possibilities, the nature of the counteranion, the metal-to-ligand ratio, the flexibility of the organic building blocks, the number and orientation of the coordinating sites in the organic spacers, and the solvent of recrystallization, among others. 2 Nevertheless, to gain more information about those subtle factors that are not yet well-understood, we have undertaken a study on the effect of one parameter at a time upon the topology of the networks by carrying out a systematic examination of a series of supramolecular coordination polymers using the same building block, same metal center, and same experimental conditions and varying only one or two parameters at time. 3 A study of inorganic-organic supramolecular architectures was undertaken with dithiolate ligands, L n-R ) R-S(CH 2 ) n -S- R, where n is the number of CH 2 groups and R is the phenyl group, used as building blocks. 4-9 These ligands were selected for the following reasons: (i) the dithiolate building blocks afford two coordination sites to metal centers, which is the minimum number of connecting sites required to expand the coordination sphere of the metal centers into extended solid- state networks; (ii) the variation of the aliphatic segment between the S atoms, 10 hence the distance separating silver centers and the number of possible conformations, can allow us to study the influence of the flexibility of the building block upon the coordination polymers; (iii) whether the bulk of the R substituent hinders the coordinating ability of the S atoms. This may affect the coordination sphere of the metal center and consequently the expansion of the latter into the coordination polymers. On the other hand, the role of anions in supramolecular chemistry is of great interest because of its application in ion- pair recognition and especially in anion exchange. 11 In this context, we have paid attention to the role of the counteranions upon the supramolecular architectures when the diarylthioether ligands are used as building blocks. 4-9 The main reason for our interest in the role of the anions upon the topology is to synthesize materials with useful properties such as anion exchange. We have classified 8 the anions as follows: (i) spherical anions that are mainly noncoordinating (PF 6 - , SbF 6 - , BF 4 - ); (ii) moderately coordinating sulfonates ( p-TsO - , CF 3 SO 3 - , CH 3 SO 3 - , C 10 H 7 SO 3 - ); (iii) strongly coordinating carboxylate anions (CF 3 CO 2 - , C 6 H 5 CO 2 - , CF 3 CF 2 CO 2 - , CF 3 CF 2 CF 2 CO 2 - , - OOCCF 2 CF 2 COO - ); (iv) the small planar NO 3 - anion that is * To whom correspondence should be addressed. E-mail: francois.brisse@umontreal.ca. Fax: (514) 343-7586. CRYSTAL GROWTH & DESIGN 2006 VOL. 6, NO. 12 2674 - 2685 10.1021/cg060148f CCC: $33.50 © 2006 American Chemical Society Published on Web 10/24/2006