A 3-DIMENSIONAL 3-CONNECTED ANIONIC POLYMERIC NETWORK OF A SILVER(I)-CHROMIUM(III) OXALATO COMPLEX WITH TRIS-(2,2'-BIPYRIDINE)IRON(II) CATIONS

The crystal structure of [Fe-II(bpy)(3)](2+)(n) [AgCrIII(ox)(3)](2n-)( n), where bpy = bipyridine, ox = oxalate, C36H24AgCrFeN6O12, has been determined by X-ray diffraction at room temperature. Cubic crystals of tetrahedral shape have space group P2(1)3, a = 15.486(3) Angstrom, Z = 4. The absolute structure, with respect to the crystal form {(1) ove r bar (1) over bar (1) over bar}, based on the four indexed crystal fa ces, was refined on F-2 by using a full-matrix procedure to final R = 0.050. The three-dimensional three-connected polymeric anionic silver( I)-chromium-(III) tris-oxalate network consists of [Ag-I(ox)(3)] and [ Cr-III(ox)(3)] subunits. These subunits and the cationic complex [Fe-I I(bpy)(3)](2+), which templates the structure, are all chiral and exhi bit the A configuration Lambda The chirality of the anionic decagon co nnected network corresponds to right-handed helicity. The cationic com plexes fill the voids within the anionic network, and the iron(II) cen ters occupy sites with symmetry 3 at positions x, x, x (Wyckoff letter a). The Ag and Cr atoms occupy also special positions on three-fold r otation axes (Wyckoff letter a). The shortest distance between Ag and Cr in the three-dimensional network is 5.579(2) Angstrom. There are on ly weak hydrogen bonding contacts of type C-H...O between the bpy liga nds and the oxalate oxygen atoms as accepters. Overall, this structure represents a rare case of a chiral polymeric decagon framework type w hich has been accomplished because of the special coordination algorit hm of the linking metal ions as well as of the choice of the bis-chela ting ligands.