Pentacarbonyl(imidazolidine-2-thione-κS)tungsten(0)

In the title complex, [W(C3H6N2S)(CO)5], the W atom displays an octahedral coordination with five CO molecules and an imidazolidine-2-thione molecule. The W(CO)5 unit is coordinated by the cyclic thione ligand through a W—S dative bond. The W—S and C—S bond lengths are 2.599 (2) and 1.711 (9) Å, respectively. This last distance is significantly longer than that of free cyclic thioureas. The geometry of the title compound suggests sp 3-hybridization of the S atom caused by the greatly polarized linkage W—S—C bond angle, which is close to tetrahedral [109.50 (3)°]. In the crystal packing, N—H⋯O and N—H⋯S hydrogen-bonding interactions stabilize the structure and build up chains parallel to [101].

In the title complex, [W(C 3 H 6 N 2 S)(CO) 5 ], the W atom displays an octahedral coordination with five CO molecules and an imidazolidine-2-thione molecule. The W(CO) 5 unit is coordinated by the cyclic thione ligand through a W-S dative bond. The W-S and C-S bond lengths are 2.599 (2) and 1.711 (9) Å , respectively. This last distance is significantly longer than that of free cyclic thioureas. The geometry of the title compound suggests sp 3 -hybridization of the S atom caused by the greatly polarized linkage W-S-C bond angle, which is close to tetrahedral [109.50 (3) ]. In the crystal packing, N-HÁ Á ÁO and N-HÁ Á ÁS hydrogen-bonding interactions stabilize the structure and build up chains parallel to [101].

Pentacarbonyl(imidazolidine-2-thione-S)tungsten(0)
S. Merniz, M. Mokhtari, H. Mousser, L. Ouahab and A. Mousser Comment Imidazolinethiones or cyclic thioureas are an important classe of compounds with a wide variety of applications (Gok & çetinkaya, 2004;Kuhn & Kratz, 1993). The chemical interests of these cyclic thioureas lie in their face capping character, in their structural analogy with thiolated nucleosides and in their application to enzyme models (Reglinski et al., 1999;Crossley et al., 2006;Saito et al., 2007). The diverse properties of the cyclic thioureas have been attributed to the coordination ability of the heterocyclic RN-C(S)-NR' thioamide group, as a monodentate ligand, to both metallic and non-metallic elements, leading to stable electron donor-acceptor complexes (Raper et al., 1983). Our research has been focused for some time on coordination compounds of sulfur containing ligands with carbonyl metals. The structure of the Imidazolidine-2-Thione-W(CO) 5 complex (I), was carried out and results are presented here.
The tungsten atom displays octahedral geometry with five CO and the Imidazolidine-2-Thione molecules (Fig. 1). The bond distances and angles in (I) are within normal range and are comparable to the corresponding values observed in similar structures (Saito et al., 2007;Mak et al., 1985;Valdés-Martinez et al., 1988;Valdés-Martinez et al., 1996;Pasynsky et al., 2007;Darensbourg et al., 1999). Such geometry of (I) suggests sp3 hybridization of the sulfur atom caused by the greatly polarized M-S-C linkage. Indeed, the W-S-C bond angles is 109.50 (3)° and is close to a tetrahedral angle.
As expected, the C=S bond is elongated and the C(6)-S(1) interatomic distance is 1.711 (9) Å and it is significantly longer than that of free cyclic thiourea, 1.690 (2) Å (Mak et al., 1985;Kuhn et al., 1998). The bond length between the metal and trans-carbonyl carbon atoms is 1.970 (10) Å. This is substantially shorter than the metal cis carbonyl bonds. The average of the separations between the metal and cis carbonyls is 2.049 Å.
Intermolecular N-H···O hydrogen bonds generate R 2 2 (14) graph-set motif (Etter et al., 1990;Bernstein et al., 1995) resulting in the formation of a pseudo dimer.  Fig.2). The N-H···S hydrogen bond distance is in the same range of there observed in the heterocyclic thione complexes (Beheshti et al., 2007).

Experimental
A solution of W(CO) 6 (527 mg, 1.5 mmol) and Imidazolidine-2-thione (153 mg, 1.5 mmol) in 40 ml of dry THF was irradiated for 2 h with vigorous stirring. The excess of W(CO) 6 was mouved by filtration and the solvent was evaporated under reduced pressure. The residue was recrystallised from THF/hexane (1:5 ratio). Bright yellow crystals were washed three times with portions of hexane, and dried under vacuum. Yield:(34%).
supplementary materials sup-2 Refinement H atoms were positined geometrically, using a riding model with C-H = 0.96 Å (U iso (H) = 1.5) (including free rotation about C-C and C-N bond) for methyl groups and with C-H = 0.93 and 0.97 Å (1.2 for aromatic and methylene groups) times U eq (C). Fig. 1. The molecular structure of (I), with atom labels and 30% probability displacement ellipsoids for non-H atoms. H atoms are represented as small spheres of arbitrary radii.