trans-Bis(pyridine-κN)bis­­(thio­cyanato-κS)palladium(II)

In the title complex, [Pd(SCN)₂(C₅H₄N)₂], the Pd^II ion has a trans-N₂S₂ square-planar coordination sphere defined by two pyridine ligands and two S-bound SCN⁻ anions. The Pd^II cation lies on an inversion centre, thus the asymmetric unit contains one half of the complex, the PdN₂S₂ moiety is exactly planar and the two pyridine rings are parallel. In the crystal, the complex mol­ecules are stacked in columns along the a-axis direction.

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Chemical scheme

Structure description

With reference to the title complex, [Pd(SCN)₂(py)₂], the crystal structures of related trans-di­pyridine-Pd^II complexes [PdX₂(py)₂] (X = Cl, Br, I; py = pyridine) have been determined previously. The chlorido complex [PdCl₂(py)₂] has three polymorphic forms, crystallizing in space groups C2/c (Viossat et al., 1993), P (Liao & Lee, 2006) and P2₁/n (Lee & Liao, 2008). The bromido complex [PdBr₂(py)₂] has one polymorph in space group P (Ha, 2016), and the iodido complex [PdI₂(py)₂] has two polymorphs in space groups C2/m (Lord et al., 2001; Grushin & Marshall, 2009) and C2/c (Grushin & Marshall, 2009).

In the title complex, the central Pd^II ion has a trans-N₂S₂ square-planar coordination geometry defined by two N atoms from two pyridine ligands and two S atoms derived from two SCN⁻ anions (Fig. 1). The complex crystallizes in the triclinic space group P and the asymmetric unit contains one half of the complex mol­ecule: the Pd atom is located on an inversion centre. Therefore, the PdN₂S₂ moiety is exactly planar and the two pyridine rings are parallel. The dihedral angle between the PdS₂N₂ plane and the pyridine ring [maximum deviation = 0.008 (1) Å] is 89.32 (5)°. The thio­cyanato ligand is almost linear displaying a S—C—N bond angle of 177.9 (2)°, and the S atoms are coordinated to the Pd^II cation with the nearly tetra­hedral Pd—S—C bond angle of 104.89 (7)°, characteristic of an S-bonded conformation (Ha, 2013).

Figure 1 The mol­ecular structure of the title complex showing the atom labelling and with displacement ellipsoids drawn at the 50% probability level for non-H atoms. [Symmetry code: (i) 2 − x, 2 − y, −z.]

In the crystal structure (Fig. 2), the complex mol­ecules are stacked in columns along [100] with d(Pd⋯Pd) = 5.2931 (4) Å, corresponding to the length of the a axis. In the columns, inter­molecular π–π inter­actions between adjacent pyridine rings are present. For Cg1 (the centroid of ring N1–C5) and Cg1ⁱ [symmetry code: (i) 2 − x, 2 − y, 1 − z], the centroid–centroid distance is 5.116 (1) Å, the planes are parallel and shifted by 4.11 Å.

Figure 2 The packing in the crystal of the title complex, viewed approximately along the a axis.

Synthesis and crystallization

A reaction mixture of K₂Pd(SCN)₄ (0.1835 g, 0.440 mmol) and pyridine (2 ml) in ethyl acetate (30 ml) was stirred for 1 h at room temperature. After evaporation of the solvent, the residue was washed with water and acetone, and dried at 323 K, to give a yellow powder (0.1141 g). Yellow crystals suitable for X-ray analysis were obtained by slow evaporation from a CH₃CN solution at room temperature.

Refinement

Crystal data, data collection and structure refinement details are summarized in Table 1.

Table 1
Experimental details

Crystal data
Chemical formula	[Pd(SCN)2(C5H5N)2]
Mr	380.76
Crystal system, space group	Triclinic, P
Temperature (K)	223
a, b, c (Å)	5.2931 (4), 6.8101 (6), 10.5213 (9)
α, β, γ (°)	96.994 (3), 98.754 (3), 107.293 (3)
V (Å^3)	352.24 (5)
Z	1
Radiation type	Mo Kα
μ (mm^−1)	1.60
Crystal size (mm)	0.19 × 0.15 × 0.09
Data collection
Diffractometer	Bruker PHOTON 100 CMOS detector
Absorption correction	Multi-scan (SADABS; Bruker, 2016)
Tmin, Tmax	0.685, 0.745
No. of measured, independent and observed [I > 2σ(I)] reflections	8943, 1397, 1383
Rint	0.019
(sin θ/λ)max (Å^−1)	0.619
Refinement
R[F^2 > 2σ(F^2)], wR(F^2), S	0.015, 0.040, 1.10
No. of reflections	1397
No. of parameters	88
H-atom treatment	H-atom parameters constrained
Δρmax, Δρmin (e Å^−3)	0.38, −0.35
Computer programs: APEX2 and SAINT (Bruker, 2016), SHELXT2014 (Sheldrick, 2015a), SHELXL2014 (Sheldrick, 2015b), ORTEP-3 for Windows (Farrugia, 2012) and PLATON (Spek, 2009).

Structural data

Computing details

Data collection: APEX2 (Bruker, 2016); cell refinement: SAINT (Bruker, 2016); data reduction: SAINT (Bruker, 2016); program(s) used to solve structure: SHELXT2014 (Sheldrick, 2015a); program(s) used to refine structure: SHELXL2014 (Sheldrick, 2015b); molecular graphics: ORTEP-3 for Windows (Farrugia, 2012) and PLATON (Spek, 2009); software used to prepare material for publication: SHELXL2014 (Sheldrick, 2015b).

trans-Bis(pyridine-κN)bis(thiocyanato-κS)palladium(II)

Crystal data

[Pd(SCN)2(C5H5N)2]	Z = 1
Mr = 380.76	F(000) = 188
Triclinic, P1	Dx = 1.795 Mg m^−3
a = 5.2931 (4) Å	Mo Kα radiation, λ = 0.71073 Å
b = 6.8101 (6) Å	Cell parameters from 8652 reflections
c = 10.5213 (9) Å	θ = 3.2–28.4°
α = 96.994 (3)°	µ = 1.60 mm^−1
β = 98.754 (3)°	T = 223 K
γ = 107.293 (3)°	Block, yellow
V = 352.24 (5) Å^3	0.19 × 0.15 × 0.09 mm

Data collection

Bruker PHOTON 100 CMOS detector diffractometer	1383 reflections with I > 2σ(I)
Radiation source: sealed tube	Rint = 0.019
φ and ω scans	θmax = 26.1°, θmin = 3.2°
Absorption correction: multi-scan (SADABS; Bruker, 2016)	h = −6→6
Tmin = 0.685, Tmax = 0.745	k = −8→8
8943 measured reflections	l = −13→13
1397 independent reflections

Refinement

Refinement on F^2	Primary atom site location: structure-invariant direct methods
Least-squares matrix: full	Secondary atom site location: difference Fourier map
R[F^2 > 2σ(F^2)] = 0.015	Hydrogen site location: inferred from neighbouring sites
wR(F^2) = 0.040	H-atom parameters constrained
S = 1.10	w = 1/[σ^2(Fo^2) + (0.0212P)^2 + 0.1471P] where P = (Fo^2 + 2Fc^2)/3
1397 reflections	(Δ/σ)max < 0.001
88 parameters	Δρmax = 0.38 e Å^−3
0 restraints	Δρmin = −0.35 e Å^−3

Special details

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

Refinement. Hydrogen atoms were positioned geometrically and allowed to ride on their respective parent atoms: C—H = 0.94 Å and U_iso(H) = 1.2U_eq(C).

Fractional atomic coordinates and isotropic or equivalent isotropic displacement parameters (Ų)

	x	y	z	Uiso*/Ueq
Pd1	1.0000	1.0000	0.0000	0.02642 (7)
S1	0.61794 (10)	0.72043 (8)	−0.10502 (5)	0.03935 (12)
N1	0.9587 (3)	0.8677 (2)	0.16016 (14)	0.0278 (3)
N2	0.5443 (4)	0.7580 (3)	−0.37129 (17)	0.0466 (4)
C1	0.8137 (4)	0.9263 (3)	0.24251 (18)	0.0347 (4)
H1	0.7276	1.0240	0.2219	0.042*
C2	0.7869 (4)	0.8482 (3)	0.35602 (18)	0.0372 (4)
H2	0.6825	0.8908	0.4116	0.045*
C3	0.9145 (4)	0.7075 (3)	0.38689 (19)	0.0401 (4)
H3	0.9014	0.6537	0.4647	0.048*
C4	1.0622 (4)	0.6460 (3)	0.3025 (2)	0.0427 (5)
H4	1.1507	0.5492	0.3219	0.051*
C5	1.0794 (4)	0.7273 (3)	0.18928 (18)	0.0344 (4)
H5	1.1782	0.6832	0.1312	0.041*
C6	0.5790 (4)	0.7453 (3)	−0.26277 (18)	0.0335 (4)

Atomic displacement parameters (Ų)

	U^11	U^22	U^33	U^12	U^13	U^23
Pd1	0.03078 (11)	0.03002 (11)	0.02182 (10)	0.01194 (8)	0.00732 (7)	0.00903 (7)
S1	0.0429 (3)	0.0392 (3)	0.0295 (2)	0.0031 (2)	0.0042 (2)	0.01138 (19)
N1	0.0295 (7)	0.0306 (7)	0.0237 (7)	0.0094 (6)	0.0051 (6)	0.0072 (6)
N2	0.0519 (10)	0.0501 (10)	0.0309 (9)	0.0071 (8)	0.0066 (8)	0.0070 (8)
C1	0.0367 (9)	0.0420 (10)	0.0311 (9)	0.0175 (8)	0.0104 (7)	0.0104 (8)
C2	0.0375 (10)	0.0444 (11)	0.0278 (9)	0.0079 (8)	0.0119 (8)	0.0064 (8)
C3	0.0459 (11)	0.0409 (10)	0.0289 (9)	0.0043 (9)	0.0058 (8)	0.0152 (8)
C4	0.0514 (12)	0.0395 (10)	0.0432 (11)	0.0191 (9)	0.0087 (9)	0.0191 (9)
C5	0.0394 (10)	0.0332 (9)	0.0350 (10)	0.0149 (8)	0.0110 (8)	0.0097 (7)
C6	0.0336 (9)	0.0302 (9)	0.0346 (10)	0.0080 (7)	0.0067 (7)	0.0040 (7)

Geometric parameters (Å, º)

Pd1—N1^i	2.0159 (14)	C1—H1	0.9400
Pd1—N1	2.0159 (14)	C2—C3	1.369 (3)
Pd1—S1^i	2.3353 (5)	C2—H2	0.9400
Pd1—S1	2.3353 (5)	C3—C4	1.375 (3)
S1—C6	1.6766 (19)	C3—H3	0.9400
N1—C5	1.338 (2)	C4—C5	1.377 (3)
N1—C1	1.341 (2)	C4—H4	0.9400
N2—C6	1.147 (3)	C5—H5	0.9400
C1—C2	1.375 (3)
N1^i—Pd1—N1	180.0	C3—C2—C1	118.98 (18)
N1^i—Pd1—S1^i	85.36 (4)	C3—C2—H2	120.5
N1—Pd1—S1^i	94.64 (4)	C1—C2—H2	120.5
N1^i—Pd1—S1	94.64 (4)	C2—C3—C4	119.03 (17)
N1—Pd1—S1	85.36 (4)	C2—C3—H3	120.5
S1^i—Pd1—S1	180.0	C4—C3—H3	120.5
C6—S1—Pd1	104.89 (7)	C3—C4—C5	119.52 (18)
C5—N1—C1	118.73 (15)	C3—C4—H4	120.2
C5—N1—Pd1	121.84 (12)	C5—C4—H4	120.2
C1—N1—Pd1	119.39 (12)	N1—C5—C4	121.49 (17)
N1—C1—C2	122.23 (17)	N1—C5—H5	119.3
N1—C1—H1	118.9	C4—C5—H5	119.3
C2—C1—H1	118.9	N2—C6—S1	177.86 (18)
C5—N1—C1—C2	0.5 (3)	C2—C3—C4—C5	0.2 (3)
Pd1—N1—C1—C2	−177.35 (14)	C1—N1—C5—C4	−1.3 (3)
N1—C1—C2—C3	0.7 (3)	Pd1—N1—C5—C4	176.46 (15)
C1—C2—C3—C4	−1.0 (3)	C3—C4—C5—N1	1.0 (3)

Symmetry code: (i) −x+2, −y+2, −z.