BUILDING 2-DIMENSIONAL SILVER(I) COORDINATION POLYMERS WITH DICARBOXYLATE-LIKE LIGANDS - SYNTHESIS AND CRYSTAL-STRUCTURES OF POLYMERIC COMPLEXES OF SILVER-NITRATE AND PERCHLORATE WITH FLEXIBLE DOUBLE BETAINES

Four novel two-dimensional silver(I) co-ordination polymers of two flexible double betaines with different quaternary ammonio side groups in the adipic acid skeleton, namely [{Ag-2(L(1))} [{Ag-2(L(1))}(n)][CIO4](2n) 1, [{Ag-2(L(2))}(n)][ClO4](2n). 2nH(2)O 2, [{Ag-2(L(1))(NO3)(2)}(n)] 3 and [{Ag-2(L(2))(NO3)(2)}(n)] 4 [L(1) = meso-2,5-bis(trimethylammonio)adipate, (O2CCH)-O--(N(+)Me(3))CH2CH2CH(N(+)Me(3))CO2-; L(2) = mes-2,5-bis(pylidinio)adipate. (O2CCH)-O--(N+C5H5)CH2CH2CH(N+C5H5)CO2-]. have been prepared and characterized by X-ray crystallography. Each complex contains dimeric subunits in which each pair of adjacent metal atoms is doubly bridged by coplanar syn-syn mu-carboxylato-O.O' groups. The dimeric subunits are extended into a step polymer through the linkage of each metal centre to a carboxylate group of an adjacent dimer. Such [Ag-2(carboxylate-O,O')(2)](n) chains are extended into sawtooth-wave layer structures in 1. 3 and 4. and an unusual corrugated layer in 2 by the cross-linkage of the adipic acid skeleton of the dauble-betaine ligands. The different ligation ability of the perchlorate and nitrate anions results in different co-ordination geometries about the silver(I) atoms. In 1 and 2. the silver(I) atom is coordinated by three carboxylato oxygen atoms in a T-shaped geometry, and the [Ag-2(carboxylate-O,O')(2)](n) chain exhibits the typical type D structure. The co-ordination geometry of the silver(I) atom in 3 is a distorted tetrahedron, and the [Ag-2(carboxylate-O,O')(2)](n) chain adopts a modified type D structure. The silver(I) atom in 4 exhibits unusual five-co-ordination in a square pyramid, and the dimer is converted into a novel paddlewheel-like structure. which is the first example found in silver(I) carboxylates.