Structural variations in novel silver(I) complexes with bitopic pyrazole/n-heterocyclic carbene ligands.

The synthesis and structural characterization of several new silver complexes of L (L = a bidendate ligand of pyrazole and N-heterocyclic carbene) are described. The result shows that the choice of counterions, N-substitutions of L, and reaction conditions are crucial which lead to a variety of structural motifs, including novel metallomacrocycles [Ag 2 (μ-L) 2 ] 2+ with or without Ag•••Ag close contact, a mononuclear [AgL 2 ] + complex, and a [LAg(NO 3 )I n coordination polymer. In particular, the nonbonding Ag•••Ag distance and the overall geometry of the metallomacrocycles are controllable with different N-substitutions and counterions. All these complexes have been determined by X-ray diffraction. The solid-state aggregates are retained in solution as supported by the electrospray mass spectroscopic studies.