Crystal structure of bis[(acetato-κO)(imidazolidine-2-thione-κS)bis(triphenylphosphane-κP)silver(I)] di-μ-imidazolidine-2-thione-κ4 S:S-bis[(imidazolidine-2-thione-κS)bis(triphenylphosphane-κP)silver(I)] diacetate acetonitrile disolvate tetrahydrate

The title compound consists of a mononuclear AgI complex, a discrete binuclear AgI complex, acetate anions, acetonitrile solvent molecules and water molecules. The molecular components are linked through O—H⋯O, N—H⋯O and O—H⋯S hydrogen bonds, forming a chain structure along [100].

In the title compound, [Ag 2 (C 3 H 6 N 2 S) 4 (C 18 H 15 P) 2 ](C 2 H 3 O 2 ) 2 Á[Ag(C 2 H 3 O 2 )-(C 3 H 6 N 2 S)(C 18 H 15 P) 2 ] 2 Á2C 2 H 3 NÁ4H 2 O, the Ag I ion in the mononuclear neutral complex exhibits a distorted tetrahedral environment with coordination by two P atoms from triphenylphosphane (PPh 3 ) ligands, one S atom of an imidazolidine-2-thione (etu) ligand and one O atom of an acetate anion. The binuclear cationic complex comprises two inversion-related [Ag(C 3 H 6 N 2 S) 2 (C 18 H 15 P)] units with Ag I ions bridged by two S atoms from etu ligands forming a four-membered Ag-S-Ag-S ring. Each Ag I ion is coordinated by a P atom of a PPh 3 ligand, two S atoms of bridging etu ligands and the terminal S atom of an etu ligand in a distorted tetrahedral environment. In the crystal, the mononuclear complex is linked to lattice water molecules through O-HÁ Á ÁO and N-HÁ Á ÁO hydrogen bonds, forming a chain along [100]. In addition, the binuclear complex molecules are connected to acetate anions and lattice water molecules via O-HÁ Á ÁO, N-HÁ Á ÁO and O-HÁ Á ÁS hydrogen bonds, also along [100].

Structural commentary
The structures of the molecular components of the title compound are shown in Fig. 1. The crystal structure consists of ISSN 2056-9890 a mononuclear neutral Ag I complex, a discrete cationic binuclear Ag I complex, acetate anions, acetonitrile solvent molecules and water molecules of crystallization. In the mononuclear complex, the Ag I ion exhibits a distorted tetrahedral environment, being coordinated by two P atoms of triphenylphosphane (PPh 3 ) ligands, one terminal S atom of a imidazolidine-2-thione (or ethylenethiourea; etu) ligand and an O atom of an acetate anion. The molecule of the binuclear complex lies across a crystallographic inversion center which is at the center of the Ag 2 S 2 core. The two Ag I ions are bridged by two S atoms of etu ligands forming a four-membered Ag-S-Ag-S ring. Each Ag I ion is in a distorted tetrahedral coordination geometry formed by a P atom of a PPh 3 ligand, the S atoms of two bridging etu ligands and a terminal S atom of an etu ligand.

Supramolecular features
In the crystal structure, O7-H7AÁ Á ÁO6, O7-H7BÁ Á ÁO6 iv , N6-H6Á Á ÁO4 and N5-H5Á Á ÁO7 iii hydrogen bonds (symmetry codes as in Table 1)  The structures of the molecular components with displacement ellipsoids drawn at the 50% probability level. H atoms are omitted for clarity. The symmetry operator for equivalent atoms of the discrete dimer is (Àx, Ày, Àz + 1). Only the symmetry-unique mononuclear complex, acetate ion, acetonitrile solvent molecule and solvent water molecules are shown.

Synthesis and crystallization
Triphenylphosphane (0.31 g, 1.18 mmol) was dissolved in 30 cm 3 of acetonitrile at 335 K. Ag(OAc) (0.10 g, 0.60 mmol) was added and the mixture was stirred for 3 h. Ethylenethiourea (0.06 g, 0.59 mmol) was added and the new reaction mixture was heated under reflux for 5 h. The resulting clear solution was filtered off and left to evaporate at room temperature. Crystals suitable for X-ray diffraction, which were deposited upon standing for a week, were filtered off and dried under reduced pressure.

Special details
Geometry. All e.s.d.'s (except the e.s.d. in the dihedral angle between two l.s. planes) are estimated using the full covariance matrix. The cell e.s.d.'s are taken into account individually in the estimation of e.s.d.'s in distances, angles and torsion angles; correlations between e.s.d.'s in cell parameters are only used when they are defined by crystal symmetry. An approximate (isotropic) treatment of cell e.s.d.'s is used for estimating e.s.d.'s involving l.s. planes.