A second monoclinic polymorph of (pyridine-2-carboxaldehyde oximato-κ2N,N′)(pyridine-2-carboxaldehyde oxime-κ2N,N′)palladium(II) chloride

Ha, K.

doi:10.1107/S1600536812001559

metal-organic compounds

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ISSN: 2056-9890

Volume 68| Part 2| February 2012| Pages m176-m177

doi:10.1107/S1600536812001559

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A second monoclinic polymorph of (pyridine-2-carboxaldehyde oximato-κ²N,N′)(pyridine-2-carboxaldehyde oxime-κ²N,N′)palladium(II) chloride

Kwang Ha ^a ^*

^aSchool of Applied Chemical Engineering, The Research Institute of Catalysis, Chonnam National University, Gwangju 500-757, Republic of Korea
^*Correspondence e-mail: hakwang@chonnam.ac.kr

(Received 10 January 2012; accepted 13 January 2012; online 21 January 2012)

The asymmetric unit of the title compound, [Pd(C₆H₅N₂O)(C₆H₆N₂O)]Cl, contains one half of a cationic Pd^II complex and a Cl⁻ anion, with a crystallographic mirror plane parallel to the ac plane passing through the Pd and Cl atoms. In the complex, the Pd^II ion is four-coordinated in a distorted square-planar environment by four N atoms derived from the two chelating ligands. The hydroxy H atom lies on the mirror plane and so is equidistant from the O atoms. This indicates that the negative charge is delocalized over the two O atoms. The complex molecules are stacked in columns along the c axis and are connected by C—H⋯O hydrogen bonds, forming a three-dimensional network. The structure reported herein represents a new monoclinic polymorph of the previously reported monoclinic (C2/c) form [Torabi et al. (2007 ). Z. Kristallogr. New Cryst. Struct. 222, 197–198].

Related literature

For the C2/c polymorph of the title compound, see: Torabi et al. (2007). For the crystal structure of the related complex [PdCl₂(C₆H₆N₂O)], see: Ha (2011 ).

Experimental

Crystal data

[Pd(C₆H₅N₂O)(C₆H₆N₂O)]Cl
M_r = 385.10
Monoclinic, C 2/m
a = 14.0865 (16) Å
b = 12.1439 (14) Å
c = 8.2723 (9) Å
β = 114.447 (2)°
V = 1288.2 (3) Å³
Z = 4
Mo Kα radiation
μ = 1.65 mm⁻¹
T = 200 K
0.22 × 0.15 × 0.10 mm

Data collection

Bruker SMART 1000 CCD diffractometer
Absorption correction: multi-scan (SADABS; Bruker, 2000 ) T_min = 0.894, T_max = 1.000
3935 measured reflections
1312 independent reflections
1188 reflections with I > 2σ(I)
R_int = 0.025

Refinement

R[F² > 2σ(F²)] = 0.030
wR(F²) = 0.075
S = 1.09
1312 reflections
97 parameters
H atoms treated by a mixture of independent and constrained refinement
Δρ_max = 0.75 e Å⁻³
Δρ_min = −0.53 e Å⁻³

Table 1
Selected geometric parameters (Å, °)

Pd1—N1	2.068 (3)
Pd1—N2	1.985 (3)

N2—Pd1—N1	78.91 (14)

Table 2
Hydrogen-bond geometry (Å, °)

D—H⋯A	D—H	H⋯A	D⋯A	D—H⋯A
O1—H1o⋯O1ⁱ	1.21 (1)	1.21 (1)	2.418 (7)	175 (7)
C2—H2⋯O1ⁱⁱ	0.95	2.49	3.178 (5)	129
Symmetry codes: (i) x, -y+1, z; (ii) $[x-{\script{1\over 2}}, -y+{\script{1\over 2}}, z-1]$ .

Data collection: SMART (Bruker, 2000); cell refinement: SAINT (Bruker, 2000); data reduction: SAINT; program(s) used to solve structure: SHELXS97 (Sheldrick, 2008 ); program(s) used to refine structure: SHELXL97 (Sheldrick, 2008); molecular graphics: ORTEP-3 (Farrugia, 1997 ) and PLATON (Spek, 2009 ); software used to prepare material for publication: SHELXL97.

Supporting information

Crystal structure: contains datablocks global, I. DOI: 10.1107/S1600536812001559/tk5047sup1.cif

Structure factors: contains datablock I. DOI: 10.1107/S1600536812001559/tk5047Isup2.hkl

checkCIF report

Comment top

The title compound, [Pd(C₁₂H₁₁N₄O₂)]Cl, was obtained as a by-product from the reaction of Na₂PdCl₄ with syn-2-pyridinealdoxime in H₂O. The X-ray crystal structure of the compound was previously reported in the monoclinic space group C2/c (Torabi et al., 2007). In the latter, the molecule does not exhibit molecular symmetry. The structure presented herein is essentially the same as the published structure but represents a new monoclinic polymorph with the space group C2/m. The yellow main product of the reaction, [PdCl₂(C₆H₆N₂O)], was investigated previously (Ha, 2011).

The asymmetric unit of the title compound contains one half of a cationic Pd^II complex and a Cl^- anion (Fig. 1). The compound is disposed about a crystallographic mirror plane parallel to the ac plane passing through the Pd and Cl atoms. In the complex, the Pd^II ion is four-coordinated in a distorted square-planar environment by four N atoms of the two chelating ligands. Formally, one of the ligands is coordinated to the Pd atom in the monoanionic form, but the negative charge is delocalized over the two O atoms of the ligands; the hydroxy H atom is located in the middle of the O atoms forming a nearly planar six-membered ring. The tight N1—Pd1—N2 chelate angle of 78.91 (14)° contributes the distortion of the square planar structure. The trans N1—Pd1—N2ⁱ (symmetry code i: x,1 - y, z) bond angle is 173.62 (12)°. The Pd1—N1(pyridine) bond length is slightly longer than the Pd1—N2(oxime) bond length (Table 1). The ligands are nearly planar, with a maximum deviation of 0.024 (3) Å from the least-squares plane, and the dihedral angle between the ligands is 5.06 (8)°. The complex molecules are stacked in columns along the c axis and are connected by intermolecular C—H···O hydrogen bonds, forming a three-dimensional network (Fig. 2 and Table 2). In the columns, intermolecular π-π interactions between the pyridine rings are present, the shortest ring centroid-centroid distance being 3.787 (3) Å.

Related literature top

For the C2/c polymorph of the title compound, see: Torabi et al. (2007). For the crystal structure of the related complex [PdCl₂(C₆H₆N₂O)], see: Ha (2011).

Experimental top

The title compound was obtained as a by-product from the reaction of Na₂PdCl₄ (0.2942 g, 1.000 mmol) with syn-2-pyridinealdoxime (0.2444 g, 2.001 mmol) in H₂O (20 ml). After stirring of the reaction mixture for 3 h at room temperature, the formed precipitate was separated by filtration, washed with H₂O and acetone, to give the main product as a yellow powder (0.2302 g) (Ha, 2011). The orange by-product in a small amount was obtained from the mixture of filtrate and washing solution. Crystals suitable for X-ray analysis were obtained by slow evaporation from an N,N-dimethylformamide (DMF) solution of the by-product at 60 °C.

Computing details top

Data collection: SMART (Bruker, 2000); cell refinement: SAINT (Bruker, 2000); data reduction: SAINT (Bruker, 2000); program(s) used to solve structure: SHELXS97 (Sheldrick, 2008); program(s) used to refine structure: SHELXL97 (Sheldrick, 2008); molecular graphics: ORTEP-3 (Farrugia, 1997) and PLATON (Spek, 2009); software used to prepare material for publication: SHELXL97 (Sheldrick, 2008).

Figures top

	Fig. 1. A view of the molecular structure of the title compound, with displacement ellipsoids drawn at the 30% probability level. Unlabelled atoms are related to the reference atoms by the (x, 1-y, z) symmetry transformation.
	Fig. 2. A view of the crystal packing of the title compound. Intermolecular hydrogen-bond interactions are drawn with dashed lines.

(pyridine-2-carboxaldehyde oximato-κ²N,N')(pyridine-2-carboxaldehyde oxime-κ²N,N')palladium(II) chloride top

Crystal data top

[Pd(C₆H₅N₂O)(C₆H₆N₂O)]Cl	F(000) = 760
M_r = 385.10	D_x = 1.986 Mg m⁻³
Monoclinic, C2/m	Mo Kα radiation, λ = 0.71073 Å
Hall symbol: -C 2y	Cell parameters from 2872 reflections
a = 14.0865 (16) Å	θ = 2.3–26.0°
b = 12.1439 (14) Å	µ = 1.65 mm⁻¹
c = 8.2723 (9) Å	T = 200 K
β = 114.447 (2)°	Prism, orange
V = 1288.2 (3) Å³	0.22 × 0.15 × 0.10 mm
Z = 4

Data collection top

Bruker SMART 1000 CCD diffractometer	1312 independent reflections
Radiation source: fine-focus sealed tube	1188 reflections with I > 2σ(I)
Graphite monochromator	R_int = 0.025
ϕ and ω scans	θ_max = 26.0°, θ_min = 2.3°
Absorption correction: multi-scan (SADABS; Bruker, 2000)	h = −17→17
T_min = 0.894, T_max = 1.000	k = −12→14
3935 measured reflections	l = −10→10

Refinement top

Refinement on F²	Primary atom site location: structure-invariant direct methods
Least-squares matrix: full	Secondary atom site location: difference Fourier map
R[F² > 2σ(F²)] = 0.030	Hydrogen site location: inferred from neighbouring sites
wR(F²) = 0.075	H atoms treated by a mixture of independent and constrained refinement
S = 1.09	w = 1/[σ²(F_o²) + (0.035P)² + 2.4037P] where P = (F_o² + 2F_c²)/3
1312 reflections	(Δ/σ)_max < 0.001
97 parameters	Δρ_max = 0.75 e Å⁻³
0 restraints	Δρ_min = −0.53 e Å⁻³

Crystal data top

[Pd(C₆H₅N₂O)(C₆H₆N₂O)]Cl	V = 1288.2 (3) Å³
M_r = 385.10	Z = 4
Monoclinic, C2/m	Mo Kα radiation
a = 14.0865 (16) Å	µ = 1.65 mm⁻¹
b = 12.1439 (14) Å	T = 200 K
c = 8.2723 (9) Å	0.22 × 0.15 × 0.10 mm
β = 114.447 (2)°

Data collection top

Bruker SMART 1000 CCD diffractometer	1312 independent reflections
Absorption correction: multi-scan (SADABS; Bruker, 2000)	1188 reflections with I > 2σ(I)
T_min = 0.894, T_max = 1.000	R_int = 0.025
3935 measured reflections

Refinement top

R[F² > 2σ(F²)] = 0.030	0 restraints
wR(F²) = 0.075	H atoms treated by a mixture of independent and constrained refinement
S = 1.09	Δρ_max = 0.75 e Å⁻³
1312 reflections	Δρ_min = −0.53 e Å⁻³
97 parameters

Special details top

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

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 > σ(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 (Å²) top

	x	y	z	U_iso*/U_eq
Pd1	0.09319 (3)	0.5000	0.41451 (4)	0.02259 (15)
O1	0.2571 (2)	0.4005 (3)	0.7251 (4)	0.0546 (9)
H1o	0.261 (5)	0.5000	0.725 (10)	0.08 (2)*
N1	0.0142 (2)	0.3633 (2)	0.2741 (4)	0.0295 (7)
N2	0.1746 (2)	0.3793 (3)	0.5732 (4)	0.0342 (7)
C1	−0.0700 (3)	0.3564 (4)	0.1201 (5)	0.0444 (11)
H1	−0.1006	0.4219	0.0576	0.053*
C2	−0.1134 (4)	0.2558 (6)	0.0502 (8)	0.075 (2)
H2	−0.1730	0.2539	−0.0599	0.090*
C3	−0.0738 (6)	0.1612 (5)	0.1328 (11)	0.092 (3)
H3	−0.1051	0.0926	0.0848	0.110*
C4	0.0139 (5)	0.1668 (4)	0.2904 (9)	0.0721 (18)
H4	0.0452	0.1013	0.3524	0.086*
C5	0.0562 (3)	0.2684 (3)	0.3576 (6)	0.0413 (10)
C6	0.1470 (3)	0.2806 (4)	0.5255 (6)	0.0457 (11)
H6	0.1831	0.2191	0.5946	0.055*
Cl1	0.23809 (11)	0.0000	0.72959 (19)	0.0424 (3)

Atomic displacement parameters (Å²) top

	U¹¹	U²²	U³³	U¹²	U¹³	U²³
Pd1	0.0211 (2)	0.0221 (2)	0.0211 (2)	0.000	0.00530 (15)	0.000
O1	0.0321 (15)	0.080 (2)	0.0384 (16)	0.0115 (16)	0.0015 (13)	0.0273 (17)
N1	0.0320 (15)	0.0266 (17)	0.0349 (17)	−0.0057 (13)	0.0187 (14)	−0.0088 (13)
N2	0.0270 (15)	0.044 (2)	0.0316 (17)	0.0108 (14)	0.0122 (13)	0.0164 (15)
C1	0.036 (2)	0.058 (3)	0.042 (2)	−0.018 (2)	0.0183 (19)	−0.023 (2)
C2	0.066 (3)	0.100 (5)	0.078 (4)	−0.058 (4)	0.048 (3)	−0.066 (4)
C3	0.120 (6)	0.059 (4)	0.141 (6)	−0.064 (4)	0.098 (5)	−0.069 (4)
C4	0.109 (4)	0.025 (2)	0.127 (5)	−0.012 (3)	0.093 (4)	−0.015 (3)
C5	0.051 (2)	0.027 (2)	0.066 (3)	−0.0016 (18)	0.044 (2)	−0.002 (2)
C6	0.048 (2)	0.037 (2)	0.068 (3)	0.020 (2)	0.040 (2)	0.027 (2)
Cl1	0.0381 (7)	0.0499 (9)	0.0418 (8)	0.000	0.0190 (6)	0.000

Geometric parameters (Å, º) top

Pd1—N1	2.068 (3)	C1—H1	0.9500
Pd1—N1ⁱ	2.068 (3)	C2—C3	1.335 (10)
Pd1—N2ⁱ	1.985 (3)	C2—H2	0.9500
Pd1—N2	1.985 (3)	C3—C4	1.377 (9)
O1—N2	1.337 (4)	C3—H3	0.9500
O1—H1o	1.210 (5)	C4—C5	1.383 (6)
N1—C1	1.336 (5)	C4—H4	0.9500
N1—C5	1.347 (5)	C5—C6	1.455 (6)
N2—C6	1.271 (5)	C6—H6	0.9500
C1—C2	1.381 (7)

N2ⁱ—Pd1—N2	95.2 (2)	C3—C2—C1	121.9 (6)
N2ⁱ—Pd1—N1	173.62 (12)	C3—C2—H2	119.1
N2—Pd1—N1	78.91 (14)	C1—C2—H2	119.1
N2ⁱ—Pd1—N1ⁱ	78.91 (14)	C2—C3—C4	117.6 (5)
N2—Pd1—N1ⁱ	173.62 (13)	C2—C3—H3	121.2
N1—Pd1—N1ⁱ	106.87 (17)	C4—C3—H3	121.2
N2—O1—H1o	103 (3)	C3—C4—C5	119.5 (5)
C1—N1—C5	117.6 (4)	C3—C4—H4	120.2
C1—N1—Pd1	130.1 (3)	C5—C4—H4	120.2
C5—N1—Pd1	112.3 (3)	N1—C5—C4	122.2 (5)
C6—N2—O1	120.6 (3)	N1—C5—C6	115.3 (3)
C6—N2—Pd1	118.2 (3)	C4—C5—C6	122.5 (5)
O1—N2—Pd1	121.3 (3)	N2—C6—C5	115.3 (4)
N1—C1—C2	121.3 (5)	N2—C6—H6	122.3
N1—C1—H1	119.4	C5—C6—H6	122.3
C2—C1—H1	119.4

N2—Pd1—N1—C1	178.8 (3)	C2—C3—C4—C5	1.1 (8)
N1ⁱ—Pd1—N1—C1	1.6 (4)	C1—N1—C5—C4	−1.1 (5)
N2—Pd1—N1—C5	0.0 (2)	Pd1—N1—C5—C4	177.9 (3)
N1ⁱ—Pd1—N1—C5	−177.22 (17)	C1—N1—C5—C6	−179.4 (3)
N2ⁱ—Pd1—N2—C6	178.0 (2)	Pd1—N1—C5—C6	−0.4 (4)
N1—Pd1—N2—C6	0.4 (3)	C3—C4—C5—N1	0.1 (7)
N2ⁱ—Pd1—N2—O1	−2.8 (3)	C3—C4—C5—C6	178.3 (4)
N1—Pd1—N2—O1	179.6 (3)	O1—N2—C6—C5	−180.0 (3)
C5—N1—C1—C2	0.9 (5)	Pd1—N2—C6—C5	−0.7 (5)
Pd1—N1—C1—C2	−177.9 (3)	N1—C5—C6—N2	0.7 (5)
N1—C1—C2—C3	0.3 (7)	C4—C5—C6—N2	−177.6 (4)
C1—C2—C3—C4	−1.3 (8)

Symmetry code: (i) x, −y+1, z.

Hydrogen-bond geometry (Å, º) top

D—H···A	D—H	H···A	D···A	D—H···A
O1—H1o···O1ⁱ	1.21 (1)	1.21 (1)	2.418 (7)	175 (7)
C2—H2···O1ⁱⁱ	0.95	2.49	3.178 (5)	129

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

Experimental details

Crystal data
Chemical formula	[Pd(C₆H₅N₂O)(C₆H₆N₂O)]Cl
M_r	385.10
Crystal system, space group	Monoclinic, C2/m
Temperature (K)	200
a, b, c (Å)	14.0865 (16), 12.1439 (14), 8.2723 (9)
β (°)	114.447 (2)
V (Å³)	1288.2 (3)
Z	4
Radiation type	Mo Kα
µ (mm⁻¹)	1.65
Crystal size (mm)	0.22 × 0.15 × 0.10

Data collection
Diffractometer	Bruker SMART 1000 CCD diffractometer
Absorption correction	Multi-scan (SADABS; Bruker, 2000)
T_min, T_max	0.894, 1.000
No. of measured, independent and observed [I > 2σ(I)] reflections	3935, 1312, 1188
R_int	0.025
(sin θ/λ)_max (Å⁻¹)	0.618

Refinement
R[F² > 2σ(F²)], wR(F²), S	0.030, 0.075, 1.09
No. of reflections	1312
No. of parameters	97
H-atom treatment	H atoms treated by a mixture of independent and constrained refinement
Δρ_max, Δρ_min (e Å⁻³)	0.75, −0.53

Computer programs: SMART (Bruker, 2000), SAINT (Bruker, 2000), SHELXS97 (Sheldrick, 2008), SHELXL97 (Sheldrick, 2008), ORTEP-3 (Farrugia, 1997) and PLATON (Spek, 2009).

Selected geometric parameters (Å, º) top

Pd1—N1	2.068 (3)	Pd1—N2	1.985 (3)

N2—Pd1—N1	78.91 (14)

Hydrogen-bond geometry (Å, º) top

D—H···A	D—H	H···A	D···A	D—H···A
O1—H1o···O1ⁱ	1.210 (5)	1.210 (5)	2.418 (7)	175 (7)
C2—H2···O1ⁱⁱ	0.95	2.49	3.178 (5)	129

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

Acknowledgements

This work was supported by the Priority Research Centers Program through the National Research Foundation of Korea (NRF) funded by the Ministry of Education, Science and Technology (2010–0029626).

References

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Sheldrick, G. M. (2008). Acta Cryst. A64, 112–122. Web of Science CrossRef CAS IUCr Journals Google Scholar
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