trans-Bis(5-amino-1,3,4-thia­diazol-2-thio­lato-κS 2)bis­(triphenyl­phosphane-κP)palladium(II) dimethyl sulfoxide disolvate hemihydrate

Felipe Chontal-Vidal; Maricela Arroyo-Gómez; Simón Hernández-Ortega; Reyna Reyes-Martínez; David Morales-Morales

doi:10.1107/S1600536812011555

. 2012 Mar 24;68(Pt 4):m483–m484. doi: 10.1107/S1600536812011555

trans-Bis(5-amino-1,3,4-thiadiazol-2-thiolato-κS ²)bis(triphenylphosphane-κP)palladium(II) dimethyl sulfoxide disolvate hemihydrate

Felipe Chontal-Vidal ^a, Maricela Arroyo-Gómez ^b, Simón Hernández-Ortega ^a, Reyna Reyes-Martínez ^a, David Morales-Morales ^a,^*

PMCID: PMC3343869 PMID: 22589843

Abstract

The title complex, [Pd(C₂H₂N₃S₂)₂(C₁₈H₁₅P)₂]·2C₂H₆OS·0.5H₂O, was obtained from the reaction of trans-[(Ph₃P)₂PdCl₂] with 5-amino-1,3,4-thiadiazole-2-thione (SSNH₂) in a 2:1 molar ratio. The Pd^II atom, located in a crystallographic center of symmetry, has a square-planar geometry with two triphenylphosphine P-coordinated molecules and two SSNH₂ ligands with the S atoms in a trans conformation. The latter ligand exhibits N—H⋯N hydrogen-bonding contacts formed by the amino group with the thiadiazole ring, generating a chain along the c axis. The asymmetric unit contains one half of the complex molecule along with disordered dimethyl sulfoxide and water molecules.

Related literature

For background to the design and synthesis of ligands that contain efficient metal coordination sites and hydrogen-bonding functionalities, see: Beatty (2001 ▶). The SSNH₂ (5-amino-1,3,4-thiadiazole-2-thiol) ligand exists in the thione and thiol forms and can converted into the thiolate form depending on the affinity of the metal, see: Tzeng et al. (1999 ▶). For SSNH₂ acting as a ligand and as auxiliary in the construction of hydrogen bonds in coordination compounds with Pd^II, see: Tzeng, Lee et al. (2004 ▶), with Pt^II, see: Tannai et al. (2006 ▶), with Cd^II, see: Gao et al. (2009 ▶) and with Au^I, see: Tzeng et al. (1999 ▶); Tzeng, Huang et al. (2004 ▶). For the thiolate form, see: Downie et al. (1972 ▶).

Experimental

Crystal data

[Pd(C₂H₂N₃S₂)₂(C₁₈H₁₅P)₂]·2C₂H₆OS·0.5H₂O
M _r = 1060.58
Orthorhombic,
a = 14.6192 (18) Å
b = 13.2572 (16) Å
c = 25.707 (3) Å
V = 4982.3 (10) Å³
Z = 4
Mo Kα radiation
μ = 0.73 mm⁻¹
T = 298 K
0.24 × 0.16 × 0.13 mm

Data collection

Bruker SMART APEX CCD area-detector diffractometer
38822 measured reflections
4590 independent reflections
2603 reflections with I > 2σ(I)
R _int = 0.107

Refinement

R[F ² > 2σ(F ²)] = 0.057
wR(F ²) = 0.137
S = 0.95
4590 reflections
322 parameters
99 restraints
H atoms treated by a mixture of independent and constrained refinement
Δρ_max = 0.63 e Å⁻³
Δρ_min = −0.37 e Å⁻³

Data collection: SMART (Bruker, 2007 ▶); cell refinement: SAINT (Bruker, 2007 ▶); data reduction: SAINT; program(s) used to solve structure: SHELXTL (Sheldrick, 2008 ▶); program(s) used to refine structure: SHELXTL; molecular graphics: SHELXTL; software used to prepare material for publication: SHELXTL.

Supplementary Material

Crystal structure: contains datablock(s) I, global. DOI: 10.1107/S1600536812011555/br2190sup1.cif

e-68-0m483-sup1.cif^{(29.7KB, cif)}

Structure factors: contains datablock(s) I. DOI: 10.1107/S1600536812011555/br2190Isup2.hkl

e-68-0m483-Isup2.hkl^{(225KB, hkl)}

Additional supplementary materials: crystallographic information; 3D view; checkCIF report

Table 1. Selected bond lengths (Å).

Pd—P1	2.3364 (15)
Pd—S2	2.3407 (14)
S2—C2	1.736 (5)

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Table 2. Hydrogen-bond geometry (Å, °).

D—H⋯A	D—H	H⋯A	D⋯A	D—H⋯A
N6—H6A⋯N4ⁱ	0.90 (1)	2.12 (2)	2.986 (7)	160 (5)

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Symmetry code: (i) Inline graphic .

Acknowledgments

RRM would like to thank CONACYT for a posdoctoral scholarship (agreement 290586-UNAM). Support of this research by CONACYT (154732) and PAPIIT (IN201711) is gratefully acknowledged.

supplementary crystallographic information

Comment

Hydrogen bonds are commonly used to generate supramolecular assemblies of coordination complexes, in this field an important area of research is the design and synthesis of ligands that contain efficient metal coordination sites and hydrogen bonding functionalities (Beatty, 2001). In this context the ligand 5-amino-1,3,4-thiadiazole-2-thiol (SSNH₂) has been used as building block for the construction of hydrogen bonded frameworks. The ligand SSNH₂ can exists in the thione and thiol forms, however it can converted into the thiolate form depending on the affinity of the metal (Tzeng, et al., 1999). Several reports of SSNH₂ acting as a ligand and as auxiliary in the construction of hydrogen bonds in coordination compounds with Pd(II) (Tzeng, Lee et al., 2004), Pt(II) (Tannai, et al., 2006), Cd(II) (Gao, et al., 2009) and Au(I) (Tzeng, et al., 1999; Tzeng, Huang et al., 2004) have been informed in the literature. Thus, in this opportunity we would like to report the crystal structure of the Pd(II) complex, trans-[(Ph₃P)₂Pd(SSNH₂)₂] DMSO, H₂O.

The molecular structure of the title compound is shown in Figure 1. The selected bond distances and angles are listed in Table 1. Only half molecule of the complex is found in the asymmetric unit and an inversion operator is needed for the generation of a whole molecule. The Pd(II) atom in the complex exhibits a square-planar arrangement, however the geometry is forced by the steric hindrance and electronic repulsions due to the interactions between the phenyl and the heterocycle rings. The SSNH₂ ligands are bonded to the metal center by the sulfur atoms in a trans arrangement with the thiadiazole groups found out of the plane of the Pd(II) coordination environment. The distance C2-S2 confirms that the ligand exists in the thiolate form (Downie, et al., 1972). The free amine group of the ligand SSNH₂ forms a hydrogen bond N6—H6A···N4 with the nitrogen atom of the thiadiazole ring related by symmetry, generating a centrosymmetric eight-member cycle, that is extended along the c-axes to form a chain framework. These chains are kept together by weak C—H···π [C9–H9···Cg(C13–C18)] intermolecular interactions. The compound crystallized with one molecule of DMSO that exhibits disorder on its structure, and one molecule of water. Weak interactions of N6—H6B···O1 (DMSO) solvent and O2—H atom of the DMSO solvent are observed. Although the solvent molecules do not participate in the strong interactions, they are important in the stabilization of the compound in the crystal lattice.

Experimental

To a CH₂Cl₂ solution (20 ml) of trans-[(Ph₃P)₂PdCl₂] (50 mg, 0.07 mmol) a solution of 5-amino-1,3,4-thiadiazole-2-thiol (20 mg, 15 mmol) and triethylamine (2 ml) in CH₂Cl₂ (20 ml) was added dropwise, and immediate change from yellow to orange was noted and the resulting reaction mixture was allowed to proceed overnight at room temperature under stirring. After this time, a reddish-orangey precipitated was noted, and the solution was filtered under vacuum to afford compound trans-[(Ph₃P)₂Pd(SSNH₂)₂] (59 mg, 95% yield). Crystals suitable for single-crystal X-ray diffraction analysis were obtained from DMSO/ⁱPrOH.