Synthesis, crystal structure and characterization of two polymeric silver(I) complexes containing imidazolate anions

Two new imidazolate-containing complexes, [Ag-5(Im)(5)](n) ( 1) and [Ag(2-MeIm)](n) ( 2), were prepared and characterized by X-ray single crystal structure determination. ( 1) consists of 1-D chains running along three different directions, namely [2 (1) over bar (1) over bar], [(2) over bar (1) over bar (1) over bar] and [2 (1) over bar (1) over bar]. This type of packing of chains is unusual. The chains are linked to form a three-dimensional structure through weak Ag center dot center dot center dot Ag interactions. The silver( I) atom in each chain is linearly coordinated by two nitrogen atoms from different imidazolates and the 1-D chain is somewhat helical due to the geometrical constraints imposed by the 1,3-arrangement of the nitrogen atoms in the imidazolate bridges. ( 2) is a linear chain in which each silver( I) atom is two-coordinated with the different bridged methylimidazolate nitrogen atoms. The two structures were refined to R-1 = 0.0315 for (1) and R-1 = 0.0495 for (2). Complexes ( 1) and ( 2) are sparingly soluble and very stable in CH3CN containing 0.1 mol center dot L-1 of n-Bu4NBF4 in the range 2.0 to -2.0V at room temperature and do not undergo any redox process. When being boiled in a solution of 30% sodium hydroxide for two hours, the large colorless prismatic crystals of ( 1) and ( 2) remain unchanged. TG/DTG analyses shows that the two complexes begin to decompose at 382 degrees C for ( 1) and 357 degrees C for ( 2).