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 [Ag-2(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 d(10) 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. (C) 2008 Elsevier Ltd. All rights reserved.