Di­chlorido­(o-phenyl­enedi­amine)­palladium(II)

The Pd^II atom in the title compound, [PdCl₂{(C₆H₄)(NH₂)₂}], lies on a twofold rotation axis and has a square-planar coordination environment defined by two N atoms of an o-phenyl­enedi­amine ligand and two Cl⁻ ions. In the crystal, the planar Pd complex mol­ecules are stacked parallel to the c axis, resulting in a columnar structure. In the column, an infinite almost straight Pd chain is formed, suggesting weak metal–metal inter­actions. The crystal packing is stabilized by a three-dimensional N—H⋯Cl hydrogen-bonding network between the amino groups and the Cl ligands of adjacent mol­ecules.

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Chemical scheme

Structure description

The mol­ecular structure of the title compound is displayed in Fig. 1. Its asymmetric unit comprises half of a [PdCl₂{(C₆H₄)(NH₂)₂}] mol­ecule, the other half being completed by application of a twofold rotation operation. The Pd^II atom is coordinated by two N atoms of an o-phenyl­enedi­amine mol­ecule and two Cl⁻ ions in a slightly distorted square-planar configuration (Table 1). The r.m.s. deviation of the least-squares plane formed by atoms Pd1, N1, C1, C2 and C3 is 0.0176 Å. The Pd1—N1 [2.0297 (13) Å] and Pd1—Cl1 [2.3159 (4) Å] bond lengths are consistent with those reported for cis-[PdCl₂(NH₃)₂] [Pd—N = 1.99 (4) and 2.13 (4) Å, Pd—Cl = 2.26 (2) and 2.29 (2) Å; Kirik et al., 1996], for [PdCl₂(en)] [en is ethyl­enedi­amine; Pd—N = 1.978 (12) Å, Pd—Cl = 2.309 (3) Å; Iball et al., 1975] or for [PdCl₂(tn)] [tn is 1,3-di­amino­propane; Pd—N = 2.036 (2) Å, Pd—Cl = 2.3296 (15) Å; Odoko & Okabe, 2006]. Bond lengths and angles of the o-phenyl­enedi­amine moiety (Table 1) are not significantly different from those of the bis­(o-phenyl­enedi­amine)­platinum(II) complex, [Pt(C₆H₈N₂)₂]Cl₂·2H₂O [N—C = 1.450 (2) Å, C—C = 1.365 (6)–1.389 (4) Å; Konno & Matsushita, 2006].

Table 1
Selected geometric parameters (Å, °)

N1—C1	1.458 (2)	C2—C3	1.371 (3)
C1—C1^i	1.375 (3)	C3—C3^i	1.416 (8)
C1—C2	1.391 (2)
N1—Pd1—N1^i	84.36 (8)	C1—N1—Pd1	110.22 (10)
N1—Pd1—Cl1	90.71 (4)	C1^i—C1—C2	120.62 (12)
Cl1^i—Pd1—Cl1	94.26 (2)	C1^i—C1—N1	117.58 (8)
N1—Pd1—Pd1^ii	95.75 (4)	C2—C1—N1	121.80 (16)
Cl1—Pd1—Pd1^ii	94.083 (12)	C3—C2—C1	119.3 (2)
N1—Pd1—Pd1^iii	84.83 (4)	C2—C3—C3^i	120.13 (16)
Cl1—Pd1—Pd1^iii	85.393 (12)
Symmetry codes: (i) ; (ii) -x+1, -y+1, -z; (iii) -x+1, -y+1, -z+1.

Figure 1 A view of the mol­ecular structure of the title compound, showing the atomic numbering scheme. Displacement ellipsoids are drawn at the 50% probability level for non-H atoms. Non-labelled atoms are related to labelled atoms by (−x + 1, y, −z + ).

As shown in Fig. 2, the neutral planar mol­ecules of the title compound stack parallel to the c axis, resulting in a columnar structure. The planar [PdCl₂{(C₆H₄)(NH₂)₂}] units are arranged in parallel and the o-phenyl­enedi­amine moieties alternate with each other owing to the c-glide operation. In the column, an infinite almost straight [Pd⋯Pd⋯Pd = 179.232 (7)°] Pd chain is formed with a short inter­atomic distance [Pd⋯Pd = 3.3510 (6) Å], suggesting weak metal–metal inter­actions. The Pd⋯Pd distance of the title compound is slightly shorter than those of cis-[PdCl₂(NH₃)₂] [3.3886 (1) Å; Kirik et al., 1996] or [PdCl₂(en)] [3.369 Å; Iball et al., 1975], which have similar columnar structures.

Figure 2 A view of the columnar structure of the title compound. Light-blue dashed lines represent hydrogen bonds between adjacent mol­ecules in the column. Yellow dashed lines display the short contact between Pd atoms in the column. [Symmetry codes: (i) −x + 1, −y + 1, −z; (ii) −x + 1, −y + 1, −z + 1; (iii) x, y, z + 1].

The shorter inter­molecular Pd⋯Pd distance of the title compound suggests that the columnar structure is stabilized by weak metal–metal inter­actions. The columnar structure of the title compound is further stabilized by inter­molecular N—H⋯Cl hydrogen bonds between adjacent mol­ecules in the column (Fig. 2 and Table 2). Inter­columnar hydrogen bonds also help to stabilize the crystal packing of the columns (Fig. 3 and Table 2).

Table 2
Hydrogen-bond geometry (Å, °)

D—H⋯A	D—H	H⋯A	D⋯A	D—H⋯A
N1—H1A⋯Cl1^iv	0.90	2.54	3.3508 (15)	151
N1—H1B⋯Cl1^v	0.90	2.74	3.3860 (15)	129
N1—H1B⋯Cl1^vi	0.90	2.66	3.3278 (15)	132
Symmetry codes: (iv) ; (v) ; (vi) -x, -y+1, -z.

Figure 3 The crystal packing of the title compound, viewed along the c axis. Light-blue dashed lines represent the inter­columnar hydrogen bonds. Magenta solid lines indicate the unit cell.

Synthesis and crystallization

To an aqueous HCl solution (1.0 M, 20 ml) of K₂[PdCl₄] (0.050 mmol, 16 mg) was slowly added an aqueous HCl solution (1.0 M, 20 ml) of o-phenyl­enedi­amine (0.050 mmol, 5 mg), and then the solution was sealed in a screw-cap vial and was kept at 323 K for 24 h in the dark. Pale-yellow needle-like crystals suitable for X-ray analysis were obtained (yield 28%). Elemental analysis: found: C, 25.17; H, 2.93; N, 9.64%, calculated for C₆H₈Cl₂N₂Pd: C, 25.24; H, 2.82; N, 9.81%. Elemental analysis was carried out by Laboratory of Organic Elemental Analysis, Department of Chemistry, Graduate School of Science, The University of Tokyo.

Refinement

Crystal data, data collection and structure refinement details are summarized in Table 3. The maximum and minimum electron density peaks are located 1.68 Å from atom Pd1 and 0.78 Å from atom Pd1, respectively.

Table 3
Experimental details

Crystal data
Chemical formula	[PdCl2(C6H8N2)]
Mr	285.44
Crystal system, space group	Monoclinic, P2/c
Temperature (K)	296
a, b, c (Å)	7.0734 (8), 10.4076 (12), 6.7019 (12)
β (°)	116.683 (4)
V (Å^3)	440.83 (11)
Z	2
Radiation type	Mo Kα
μ (mm^−1)	2.65
Crystal size (mm)	0.22 × 0.11 × 0.07
Data collection
Diffractometer	Rigaku R-AXIS RAPID imaging-plate
Absorption correction	Multi-scan (ABSCOR; Higashi, 1995)
Tmin, Tmax	0.611, 0.824
No. of measured, independent and observed [F^2 > 2σ(F^2)] reflections	11439, 1578, 1449
Rint	0.022
(sin θ/λ)max (Å^−1)	0.756
Refinement
R[F^2 > 2σ(F^2)], wR(F^2), S	0.020, 0.053, 1.09
No. of reflections	1578
No. of parameters	52
H-atom treatment	H-atom parameters constrained
Δρmax, Δρmin (e Å^−3)	1.07, −0.77
Computer programs: RAPID-AUTO (Rigaku, 1998), SHELXS97 and SHELXL97 (Sheldrick, 2008), DIAMOND (Brandenburg, 2017) and publCIF (Westrip, 2010).

Structural data

Computing details

Data collection: RAPID-AUTO (Rigaku, 1998); cell refinement: RAPID-AUTO (Rigaku, 1998); data reduction: RAPID-AUTO (Rigaku, 1998); program(s) used to solve structure: SHELXS97 (Sheldrick, 2008); program(s) used to refine structure: SHELXL97 (Sheldrick, 2008); molecular graphics: DIAMOND (Brandenburg, 2017); software used to prepare material for publication: SHELXL97 (Sheldrick, 2008) and publCIF (Westrip, 2010).

Dichlorido(o-phenylenediamine)palladium(II)

Crystal data

[PdCl2(C6H8N2)]	F(000) = 276
Mr = 285.44	Dx = 2.150 Mg m^−3
Monoclinic, P2/c	Mo Kα radiation, λ = 0.71075 Å
Hall symbol: -P 2yc	Cell parameters from 6414 reflections
a = 7.0734 (8) Å	θ = 3.9–32.2°
b = 10.4076 (12) Å	µ = 2.65 mm^−1
c = 6.7019 (12) Å	T = 296 K
β = 116.683 (4)°	Needle, pale yellow
V = 440.83 (11) Å^3	0.22 × 0.11 × 0.07 mm
Z = 2

Data collection

Rigaku R-AXIS RAPID imaging-plate diffractometer	1578 independent reflections
Radiation source: X-ray sealed tube	1449 reflections with F^2 > 2σ(F^2)
Graphite monochromator	Rint = 0.022
Detector resolution: 10.00 pixels mm^-1	θmax = 32.5°, θmin = 3.2°
ω scans	h = −10→10
Absorption correction: multi-scan (ABSCOR; Higashi, 1995)	k = −15→15
Tmin = 0.611, Tmax = 0.824	l = −9→10
11439 measured reflections

Refinement

Refinement on F^2	Secondary atom site location: difference Fourier map
Least-squares matrix: full	Hydrogen site location: inferred from neighbouring sites
R[F^2 > 2σ(F^2)] = 0.020	H-atom parameters constrained
wR(F^2) = 0.053	w = 1/[σ^2(Fo^2) + (0.032P)^2 + 0.0862P] where P = (Fo^2 + 2Fc^2)/3
S = 1.09	(Δ/σ)max < 0.001
1578 reflections	Δρmax = 1.07 e Å^−3
52 parameters	Δρmin = −0.77 e Å^−3
0 restraints	Extinction correction: SHELXL97 (Sheldrick, 2008), Fc^*=kFc[1+0.001xFc^2λ^3/sin(2θ)]^-1/4
Primary atom site location: structure-invariant direct methods	Extinction coefficient: 0.126 (4)

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.

Least-squares planes (x,y,z in crystal coordinates) and deviations from them (* indicates atom used to define plane)

- 2.4031 (0.0035) x + 0.0000 (0.0000) y + 6.6544 (0.0013) z = 0.4621 (0.0016)

* 0.0000 (0.0000) Pd1 * -0.0263 (0.0008) Cl1 * 0.0315 (0.0013) N1 * 0.0022 (0.0014) C1 * -0.0016 (0.0015) C2 * 0.0034 (0.0028) C3 * 0.0263 (0.0008) Cl1_$6 * -0.0315 (0.0013) N1_$6 * -0.0022 (0.0014) C1_$6 * 0.0016 (0.0015) C2_$6 * -0.0034 (0.0028) C3_$6

Rms deviation of fitted atoms = 0.0176

Refinement. Refinement of F² against ALL reflections. The weighted R-factor wR and goodness of fit S are based on F², conventional R-factors R are based on F, with F set to zero for negative F². The threshold expression of F² > 2sigma(F²) is used only for calculating R-factors(gt) etc. and is not relevant to the choice of reflections for refinement. R-factors based on F² are statistically about twice as large as those based on F, and R- factors based on ALL data will be even larger.

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

	x	y	z	Uiso*/Ueq
Pd1	0.5000	0.498921 (11)	0.2500	0.03038 (8)
Cl1	0.23288 (6)	0.65031 (4)	0.14958 (7)	0.04182 (10)
N1	0.2865 (2)	0.35440 (13)	0.1776 (2)	0.0406 (3)
H1A	0.2218	0.3604	0.2662	0.049*
H1B	0.1874	0.3613	0.0349	0.049*
C1	0.3920 (2)	0.23028 (14)	0.2113 (2)	0.0412 (3)
C2	0.2807 (4)	0.11529 (17)	0.1706 (3)	0.0571 (4)
H2	0.1345	0.1157	0.1169	0.069*
C3	0.3889 (6)	0.00139 (14)	0.2104 (5)	0.0720 (10)
H3	0.3161	−0.0760	0.1853	0.086*

Atomic displacement parameters (Ų)

	U^11	U^22	U^33	U^12	U^13	U^23
Pd1	0.02747 (9)	0.03112 (10)	0.02949 (10)	0.000	0.01007 (6)	0.000
Cl1	0.03435 (16)	0.03968 (17)	0.0480 (2)	0.00551 (12)	0.01543 (14)	0.00033 (14)
N1	0.0340 (6)	0.0396 (6)	0.0424 (6)	−0.0047 (5)	0.0120 (5)	−0.0018 (5)
C1	0.0559 (8)	0.0341 (6)	0.0324 (6)	−0.0043 (5)	0.0188 (6)	−0.0011 (5)
C2	0.0783 (12)	0.0449 (8)	0.0486 (9)	−0.0199 (8)	0.0288 (9)	−0.0076 (7)
C3	0.132 (3)	0.0362 (9)	0.0565 (15)	−0.0183 (8)	0.0496 (19)	−0.0068 (6)

Geometric parameters (Å, º)

Pd1—N1	2.0297 (13)	N1—H1B	0.9000
Pd1—N1^i	2.0297 (13)	C1—C1^i	1.375 (3)
Pd1—Cl1^i	2.3159 (4)	C1—C2	1.391 (2)
Pd1—Cl1	2.3159 (4)	C2—C3	1.371 (3)
Pd1—Pd1^ii	3.3510 (6)	C2—H2	0.9300
Pd1—Pd1^iii	3.3510 (6)	C3—C3^i	1.416 (8)
N1—C1	1.458 (2)	C3—H3	0.9300
N1—H1A	0.9000
N1—Pd1—N1^i	84.36 (8)	C1—N1—Pd1	110.22 (10)
N1—Pd1—Cl1^i	174.81 (4)	C1—N1—H1A	109.6
N1^i—Pd1—Cl1^i	90.71 (4)	Pd1—N1—H1A	109.6
N1—Pd1—Cl1	90.71 (4)	C1—N1—H1B	109.6
N1^i—Pd1—Cl1	174.81 (4)	Pd1—N1—H1B	109.6
Cl1^i—Pd1—Cl1	94.26 (2)	H1A—N1—H1B	108.1
N1—Pd1—Pd1^ii	95.75 (4)	C1^i—C1—C2	120.62 (12)
N1^i—Pd1—Pd1^ii	84.83 (4)	C1^i—C1—N1	117.58 (8)
Cl1^i—Pd1—Pd1^ii	85.393 (12)	C2—C1—N1	121.80 (16)
Cl1—Pd1—Pd1^ii	94.083 (12)	C3—C2—C1	119.3 (2)
N1—Pd1—Pd1^iii	84.83 (4)	C3—C2—H2	120.4
N1^i—Pd1—Pd1^iii	95.75 (4)	C1—C2—H2	120.4
Cl1^i—Pd1—Pd1^iii	94.083 (12)	C2—C3—C3^i	120.13 (16)
Cl1—Pd1—Pd1^iii	85.393 (12)	C2—C3—H3	119.9
Pd1^ii—Pd1—Pd1^iii	179.232 (7)	C3^i—C3—H3	119.9
N1^i—Pd1—N1—C1	−0.57 (7)	Pd1—N1—C1—C1^i	1.8 (2)
Cl1^i—Pd1—N1—C1	−18.8 (5)	Pd1—N1—C1—C2	−179.16 (12)
Cl1—Pd1—N1—C1	177.81 (10)	C1^i—C1—C2—C3	0.6 (3)
Pd1^ii—Pd1—N1—C1	83.63 (10)	N1—C1—C2—C3	−178.4 (2)
Pd1^iii—Pd1—N1—C1	−96.89 (10)	C1—C2—C3—C3^i	−0.7 (5)

Symmetry codes: (i) −x+1, y, −z+1/2; (ii) −x+1, −y+1, −z; (iii) −x+1, −y+1, −z+1.

Hydrogen-bond geometry (Å, º)

D—H···A	D—H	H···A	D···A	D—H···A
N1—H1A···Cl1^iv	0.90	2.54	3.3508 (15)	151
N1—H1B···Cl1^v	0.90	2.74	3.3860 (15)	129
N1—H1B···Cl1^vi	0.90	2.66	3.3278 (15)	132

Symmetry codes: (iv) x, −y+1, z+1/2; (v) x, −y+1, z−1/2; (vi) −x, −y+1, −z.