Acetato(1,10-phenanthroline-5,6-dione)silver(I) trihydrate

In the structure of the title compound, [Ag(C2H3O2)(C12H6N2O2)]·3H2O, the AgI atom is coordinated by both 1,10-phenanthroline-5,6-dione N atoms and one O atom from the acetate anion. The three water molecules are involved in extensive hydrogen bonding to each other and to the acetate O and 1,10-phenanthroline-5,6-dione O atoms. In addition, there are weak C—H⋯O interactions.

In the structure of the title compound, [Ag(C 2 H 3 O 2 )(C 12 H 6 -N 2 O 2 )]Á3H 2 O, the Ag I atom is coordinated by both 1,10phenanthroline-5,6-dione N atoms and one O atom from the acetate anion. The three water molecules are involved in extensive hydrogen bonding to each other and to the acetate O and 1,10-phenanthroline-5,6-dione O atoms. In addition, there are weak C-HÁ Á ÁO interactions.
RJB acknowledges the Laboratory for the Structure of Matter at the Naval Research Laboratory for access to their diffractometers.

Comment
The synthesis and understanding of multi-functional materials generated from spontaneously assembled molecules joined together non-covalently remain an important challenge in the science of molecules (Whitesides et al., 1991;Burrows et al., 1995;Galet et al., 2005). Metal complexes bearing electro-active ligands with two or more accessible oxidation states have been synthesized and shown to exhibit unique electronic structures resulting from the combination of the oxidation states of the metal and ligands (Ma et al., 2002;Calderazzo et al., 1999;Calderazzo et al., 2002;Calucci et al., 2006;Galet et al., 2005;Lei et al., 1996;Okamura et al., 2006).
While phendione usually binds to metals through it's imine N atoms (Onuegbu et al., 2007), in some cases both the N and O donors are used simultaneously (Calderazzo et al., 1999;Fox et al., 1991;Shavaleev et al., 2003a;Shavaleev et al., 2003b;Ruiz et al., 1999;Paw & Eisenberg, 1997). In light of these results, we have examined the coordination behavior of phendione with silver (Onuegbu et al., 2007). In this paper we report the synthesis and characterization of the title compound, The structure of the title compound, shown in Fig (Allen, 2002). The metrical parameters for the phendione ligand is in the normal ranges observed for complexes where only the N atoms are coordinated to a metal (Allen, 2002). The Ag-N bond lengths (2.256 (2) and 2.387 (2) Å) are similar to those found in related phenanthroline and phendione derivatives of silver (Leschke et al., 2002;Paramonov et al., 2003;Pallenberg et al., 1997;Titze et al., 1997;Onuegbu et al., 2007). In the title compound, silver is in a trigonal planar environment (Table 1).
In addition to the strong O-H···O hydrogen bonds (Table 2) formed by the water molecules to both the acetate and phendione O atoms, there are weak C-H···O hydrogen bonds between the hydrogen atoms on C2, C4 and C7 and either nitrate or phendione O atoms from an adjoining moiety.

Experimental
A flask containing 1,10-phenanthroline hydrate (1.00 g, 5.04 mmol) and potassium bromide (5.95 g, 50.0 mmol) was placed in an ice bath. Concentrated sulfuric acid (20 ml) was added in small portions, followed by drop wise addition of concentrated nitric acid (10 ml). The resulting solution was heated for 2 h at 353-358 K and cooled to room temperature. The solution was then poured into 400 ml of water and neutralized with sodium bicarbonate, after which the phendione was extracted with dichloromethane, and recrystallized using a methanol-water mixture.
The title compound was synthesized in an atmosphere saturated with N 2 . To a solution of AgCH 3 CO 2 (silver ethanoate) in 20 ml of 1:1 solution of methanol and water was added drop-wise a solution (20 ml) of 1:1 methanol: water mixture supplementary materials sup-2 containing 0.05 g of phendione. The final yellowish solution was filtered and allowed to slowly evaporate for about three weeks yielding colorless needle-shaped crystals of the title compound suitable for X-ray studies.

Refinement
C-bound H atoms were placed in geometrically idealized positions and constrained to ride on their parent atoms, with C-H = 0.95-0.98 Å and U iso (H) = 1.2U eq (C). The water H atoms were located as the highest peaks in the difference map after all other atoms had been located and refined. These all had reasonable O-H distanes and H-O-H angles and all formed hydrogen bonds with nearby O atoms. However for one H (H1W2) there was a close H1W2···H1W2 intermolecular contact (1.41 Å). When this atom was omitted from the refinement, the highest peak in the resulting difference map was in the same location. There were no other peaks which gave reasonable geometry. The water O-H distances were constrained to 0.82 Å.  Acetato(1,10-phenanthroline-5,6-dione)silver(I) trihydrate Crystal data [Ag(C 2