Unusual coordination geometries of silver(I) 4,5-diazafluoren-9-one complexes

Two complexes of silver(I) with 4,5-diazafluoren-9-one (dafone) which are the first examples of Ag-dafone complexes were synthesized and structurally characterized. Crystals of [Ag(dafone)2]NO3 · H2O (1) contain two strictly planar four-coordinate Ag(I) complexes. The silver coordination polyhedron in [Ag2(4,4′-bpy)(dafone)4]BF4 (2) is a highly distorted tetrahedron. Its crystal structure is built by a two-fold interpenetration of identical porous networks. The unusual coordination in the two compounds (planar four-coordinate d10 ion in 1, chelation with two long Ag–N bonds in 2 and low bond valence sums in both complexes) is in part due to the large chelate bite of dafone, and in part due to the stacking and other intermolecular interactions influencing the coordination geometry of Ag(I). This was further probed through molecular simulation of [Ag(N–N)2]+ complexes using DFT calculations.

Large chelate bite of dafone and intermolecular interactions lead to planar 4-coordination for Ag(I) in [Ag(dafone)2]+ (1) and weak chelation (both bonds weak) in [Ag2(4,4′-bpy)(dafone)4]2+ (2). The dinuclear cations in 2 are assembled into interpenetrating porous two-dimensional sheets by C–H⋯F and C–H⋯O interactions.Figure optionsDownload as PowerPoint slide