Bis[3,3-dimethyl-2-(2-oxoethyl­idene)indolinyl-κ2 N,O]palladium(II)

Hamid Khaledi; Marilyn M Olmstead; Hapipah Mohd Ali

doi:10.1107/S1600536811022069

. 2011 Jun 18;67(Pt 7):m929. doi: 10.1107/S1600536811022069

Bis[3,3-dimethyl-2-(2-oxoethylidene)indolinyl-κ² N,O]palladium(II)

Hamid Khaledi ^a,^*, Marilyn M Olmstead ^b, Hapipah Mohd Ali ^a

PMCID: PMC3152092 PMID: 21836913

Abstract

The asymmetric unit of the title compound, [Pd(C₁₂H₁₂NO)₂], consists of three crystallographically independent half-molecules. Each Pd^II atom lies on a center of inversion and is four-coordinated by two monoanionic forms of the aminoacrylaldehyde in a square-planar geometry. In the crystal, adjacent molecules are connected through C—H⋯π and C—H⋯O interactions into a three-dimensional polymeric structure.

Related literature

For the structures of related compounds, see: Khaledi et al. (2011 ▶).

Experimental

Crystal data

[Pd(C₁₂H₁₂NO)₂]
M _r = 478.85
Triclinic,
a = 10.453 (2) Å
b = 12.669 (3) Å
c = 13.056 (3) Å
α = 87.750 (3)°
β = 73.271 (3)°
γ = 70.565 (3)°
V = 1558.5 (6) Å³
Z = 3
Mo Kα radiation
μ = 0.92 mm⁻¹
T = 100 K
0.18 × 0.09 × 0.06 mm

Data collection

Bruker APEXII CCD diffractometer
Absorption correction: multi-scan (SADABS; Sheldrick, 1996 ▶) T _min = 0.853, T _max = 0.947
13381 measured reflections
6083 independent reflections
4905 reflections with I > 2σ(I)
R _int = 0.042

Refinement

R[F ² > 2σ(F ²)] = 0.037
wR(F ²) = 0.095
S = 1.03
6083 reflections
403 parameters
H-atom parameters constrained
Δρ_max = 1.35 e Å⁻³
Δρ_min = −0.75 e Å⁻³

Data collection: APEX2 (Bruker, 2007 ▶); cell refinement: SAINT (Bruker, 2007 ▶); data reduction: SAINT; program(s) used to solve structure: SHELXS97 (Sheldrick, 2008 ▶); program(s) used to refine structure: SHELXL97 (Sheldrick, 2008 ▶); molecular graphics: X-SEED (Barbour, 2001 ▶); software used to prepare material for publication: SHELXL97 and publCIF (Westrip, 2010 ▶).

Supplementary Material

Crystal structure: contains datablock(s) I, global. DOI: 10.1107/S1600536811022069/is2718sup1.cif

e-67-0m929-sup1.cif^{(25.1KB, cif)}

Structure factors: contains datablock(s) I. DOI: 10.1107/S1600536811022069/is2718Isup2.hkl

e-67-0m929-Isup2.hkl^{(297.7KB, hkl)}

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

Table 1. Hydrogen-bond geometry (Å, °).

Cg1 and Cg2 are the centroids of the benzene C27–C32 and C3–C8 rings, respectively.

D—H⋯A	D—H	H⋯A	D⋯A	D—H⋯A
C4—H4⋯O2ⁱ	0.95	2.40	3.353 (5)	177
C7—H7⋯O1ⁱⁱ	0.95	2.34	2.965 (4)	123
C19—H19⋯O2ⁱ	0.95	2.27	2.860 (5)	120
C31—H31⋯O3ⁱⁱⁱ	0.95	2.25	2.861 (5)	121
C9—H9⋯Cg1^iv	0.95	2.85	3.794 (5)	170
C33—H33⋯Cg2ⁱ	0.95	2.76	3.630 (4)	153

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Symmetry codes: (i) Inline graphic ; (ii) ; (iii) ; (iv) .

Acknowledgments

The authors thank the University of Malaya for funding this study (FRGS grant No. FP004/2010B).

supplementary crystallographic information

Comment

We have recently reported the reaction of 2-(diformylmethylidene)-3,3-dimethylindole, I, (Fig. 2), with palladium(II) ion to produce the complex II (Khaledi et al., 2011). As was reported, further recrystallization of the obtained N₂O₂-coordinated Pd^II complex from a mixture of DMF and pyridine led to the formation of acyl-palladium complexes III & IV. We were surprised to discover that leaving the recrystallization solution at room temperature for a longer time gave rise to slow disappearance of crystals of III & IV and formation of the orange crystals of the title compound. Herein, we report the crystal structure of the obtained Pd^II complex.

The crystal structure is composed of three square planar centrosymmetric complexes. In each molecule, two monoanionic ligands chelate the Pd^II ion in an N,O-mode to form two six-membered rings with the metal atom. The O—Pd—N bite angles are 90.38 (11), 90.13 (11) and 91.08 (11)° for the complexes of Pd1, Pd2 and Pd3, respectively. The three complexes have little difference in their geometries, but differ more in their intermolecular interactions. The Pd1 and Pd3 complexes are connected through C—H···π interactions (Table 1), forming infinite layers parallel to the ac plane. The layers are further linked into a three dimensional network via C—H···O hydrogen bonds (Table 1) formed between Pd1 and Pd2 molecules. Intramolecular C—H···O hydrogen bonding occurs in all three complexes.

Experimental

A solution of palladium(II) complex II (Fig. 2) in a mixture of DMF and pyridine yielded the yellowish green crystals of III and IV in two weeks. Upon standing of the solution in a closed vial at room temperature for a month, the orange crystals of the title compound appeared while the former crystals began to disappear slowly and finally disappeared completely after two months.