(Acetonitrile-κN)iodidobis(triphenylphosphane-κP)copper(I)

In the mononuclear title complex, [CuI(CH3CN)(C18H15P)2], the CuI ion is in a distorted tetrahedral geometry, coordinated by two P atoms of two triphenylphosphane ligands, one N atom of an acetonitrile ligand and one iodide anion. The acetonitrile ligand is disordered over two sets of sites in a 0.629 (15): 0.371 (15) ratio. In the crystal, weak C—H⋯I hydrogen bonds link the molecules, forming a chain along [100].

In the mononuclear title complex, [CuI(CH 3 CN)(C 18 H 15 P) 2 ], the Cu I ion is in a distorted tetrahedral geometry, coordinated by two P atoms of two triphenylphosphane ligands, one N atom of an acetonitrile ligand and one iodide anion. The acetonitrile ligand is disordered over two sets of sites in a 0.629 (15): 0.371 (15) ratio. In the crystal, weak C-HÁ Á ÁI hydrogen bonds link the molecules, forming a chain along [100].
Financial support from the Department of Chemistry, Prince of Songkla University, is gratefully acknowledged. We would like to thank Dr Matthias Zeller for his valuable suggestions and assistance with the X-ray structure determination and use of structure refinement programs.

Experimental
Triphenylphosphane (0.14g, 0.5 mmol) was dissolved in 30 cm 3 of acetonitrile in a round flask equipped with reflux condenser and magnetic stirrer at 335 K. CuI (0.10g, 0.5 mmol) was added and the mixture was stirred for 6 hrs. Solid 5amino-1,3,4-thiadiazole-2-thiol (0.07 g, 0.05 mmol) was added and the new reaction mixture was heated under reflux for 8 hrs where upon the precipitate gradually disappeared. The resulting clear solution was filtered and left to evaporate at room temperature. Colorless crystals, which deposited upon standing for several days, were filtered off, washed with acetone and dried in vacuo (0.09 g, yield 29%). Mp = 456-458 K.

Refinement
Reflections 0 1 1 and 0 1 2 were affected by the beam stop and were omitted from the refinement.The H atoms were positioned geometrically and refined using a riding model, with C-H = 0.95 with U iso (H) = 1.2 U eq (C) for H atoms on C(sp 2 ) and 0.98 Å with U iso (H) = 1.5 U eq (C) for H atoms on C(sp 3 ). The acetonitrile exhibits disorder over two different orientations. The occupancies refined to 0.629 (15) and 0.371 (15).

Results and discussion
Copper(I) complexes have many applications. Many of these complexes have been of increasing interest due to the variety of their structures and their similarity to metallothioneins. The role of copper(I) is evident in several biologically important reactions, such as a dioxygen carrier and models for several enzymes (Krupanidhi et al., 2008). On the other hand, these compounds have been reported to be luminescent (Aslanidis et al., 2010;Gallego et al., 2012) and exhibit corrosion inhibiting properties (Tian et al., 2004). Herein, the title complex was prepared by reacting copper (I) iodide and triphenylphosphane (PPh 3 ), followed by the addition of 5-amino-1,3,4-thiadiazole-2-thiol (ATM) in acetonitrile solvent. An unexpexted complex [CuI(C 18 H 15 P) 2 (CH 3 CN)] was formed in the absence of ATM in low yield (29%) (Fig.1).
The coordination environment around the Cu I ion is a distorted tetrahedral geometry fromed by two P atoms of two triphenylphosphine ligands, one N atom of disordered acetonitrile ligand and one iodide atom. The occupancies of the disorder sites of the acetonitrile ligand refined to 0.629 (15) and 0.371 (15). The Cu1-N1 bond distance of 2.055 (10) Å is slightly longer than that found in for example [Cu(C 15 H 4 BF 18 N 6 )(C 2 H 3 N)], which is 1.888 (3) Å (Balili & Pintauer, 2007). The acetonitrile ligand is almost linear with an N-C-C angle of 177.4 (14)° [or 174 (3)° for the minor component of disorder]. The typical value for an acetonitrile ligand, as for the [Cu(CH 3 CN) 4 ] + cation (Royappa et al., 2013) are angles in the range 178.4 (3)-179 (3)°. In the crystal, the molecules are connected via weak C2-H2A···I1 i interactions, forming a one-dimensional chain along the a-axis direction (Fig.2).

Figure 1
The molecular structure of the title compound with displacement ellipsoids shown at the 30% probability level. The disorder is not shown.

Figure 2
Part of the crystal structure showing weak intermolecular C-H···I hydrogen bonds (dashed lines), leading to the formation of a 1-D chain along the a-axis direction (symmetry code (i): x+1, y, z).