Hexaaqua­cadmium(II) bis­{[N-(2-oxidobenzyl­idene)glycyl-l-leucinato]cuprate(II)} dihydrate

Guolin Zhang; Lihua Ye; Yanyan Zhang; Wenlong Liu

doi:10.1107/S1600536807063635

. 2007 Dec 6;64(Pt 1):m94–m95. doi: 10.1107/S1600536807063635

Hexaaquacadmium(II) bis{[N-(2-oxidobenzylidene)glycyl-l-leucinato]cuprate(II)} dihydrate

Guolin Zhang ^a, Lihua Ye ^a, Yanyan Zhang ^a, Wenlong Liu ^a,^*

PMCID: PMC2914968 PMID: 21200661

Abstract

The title compound, [Cd(H₂O)₆][Cu(C₁₅H₁₇N₂O₄)]₂·2H₂O, has a chiral structure. Copper has a square-planar coordination with two N and two O atoms of the quadridentate chiral Schiff base ligand. The Cd²⁺ ion is coordinated by six aqua ligands with a slightly distorted octahedral configuration. Ions are linked by O—H⋯O hydrogen bonds, and the [Cd(H₂O)₆]²⁺ cations and [CuL]⁻ anions (L = Schiff base derived from glycyl-l-leucine and salicylaldehyde) occupy a stacking structure within well separated columns along the a axis. The two crystallographically independent copper–Schiff base anions each have a chiral carbon centre with an S configuration. They are related by a non-crystallographic twofold rotation axis parallel to the [010] direction.

Related literature

For related literature, see: Liu et al. (2004 ▶).

Experimental

Crystal data

[Cd(H₂O)₆][Cu(C₁₅H₁₇N₂O₄)]₂·2H₂O
M _r = 962.22
Monoclinic,
a = 7.0569 (6) Å
b = 17.4745 (14) Å
c = 15.9430 (13) Å
β = 100.680 (1)°
V = 1932.0 (3) Å³
Z = 2
Mo Kα radiation
μ = 1.71 mm⁻¹
T = 296 (2) K
0.30 × 0.28 × 0.23 mm

Data collection

Bruker SMART APEX CCD diffractometer
Absorption correction: multi-scan (SADABS; Sheldrick, 2004 ▶) T _min = 0.602, T _max = 0.678
15044 measured reflections
6936 independent reflections
6430 reflections with I > 2σ(I)
R _int = 0.024

Refinement

R[F ² > 2σ(F ²)] = 0.024
wR(F ²) = 0.054
S = 1.01
6936 reflections
494 parameters
361 restraints
H atoms treated by a mixture of independent and constrained refinement
Δρ_max = 0.33 e Å⁻³
Δρ_min = −0.28 e Å⁻³
Absolute structure: Flack (1983 ▶), 3005 Friedel pairs
Flack parameter: 0.008 (9)

Data collection: SMART (Bruker, 2002 ▶); cell refinement: SAINT-Plus (Bruker, 2003 ▶); data reduction: SAINT-Plus; program(s) used to solve structure: SHELXS97 (Sheldrick, 1997 ▶); program(s) used to refine structure: SHELXL97 (Sheldrick, 1997 ▶); molecular graphics: SHELXTL (Bruker, 2000 ▶); software used to prepare material for publication: SHELXTL.

Supplementary Material

Crystal structure: contains datablocks I, global. DOI: 10.1107/S1600536807063635/si2059sup1.cif

e-64-00m94-sup1.cif^{(29KB, cif)}

Structure factors: contains datablocks I. DOI: 10.1107/S1600536807063635/si2059Isup2.hkl

e-64-00m94-Isup2.hkl^{(339.4KB, hkl)}

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

Table 1. Selected geometric parameters (Å, °).

Cd1—O10	2.228 (2)
Cd1—O13	2.268 (3)
Cd1—O12	2.280 (2)
Cd1—O9	2.281 (2)
Cd1—O11	2.285 (2)
Cd1—O14	2.373 (2)
Cu1—O1	1.886 (2)
Cu1—N2	1.903 (2)
Cu1—N1	1.927 (3)
Cu1—O2	1.954 (2)
Cu2—O5	1.878 (2)
Cu2—N4	1.895 (3)
Cu2—N3	1.915 (3)
Cu2—O6	1.945 (2)

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O1—Cu1—N2	179.61 (11)
O1—Cu1—N1	95.61 (11)
N2—Cu1—N1	84.62 (11)
O1—Cu1—O2	95.93 (10)
N2—Cu1—O2	83.87 (11)
N1—Cu1—O2	167.28 (11)
O5—Cu2—N4	174.48 (11)
O5—Cu2—N3	96.40 (11)
N4—Cu2—N3	84.99 (11)
O5—Cu2—O6	95.53 (10)
N4—Cu2—O6	83.99 (10)
N3—Cu2—O6	165.06 (12)

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

D—H⋯A	D—H	H⋯A	D⋯A	D—H⋯A
O16—H16B⋯O8ⁱ	0.85	1.94	2.783 (4)	171
O16—H16A⋯O4ⁱⁱ	0.85	2.11	2.937 (4)	165
O15—H15B⋯O5	0.878 (18)	1.91 (2)	2.769 (3)	164 (4)
O15—H15A⋯O14ⁱⁱⁱ	0.861 (19)	1.980 (19)	2.828 (4)	168 (4)
O14—H14D⋯O4^iv	0.865 (18)	1.86 (2)	2.714 (4)	171 (3)
O14—H14E⋯O3	0.838 (17)	2.073 (18)	2.911 (3)	177 (3)
O12—H12B⋯O8^v	0.85	2.12	2.853 (3)	144
O10—H10A⋯O6^vi	0.85	1.93	2.685 (3)	147
O10—H10B⋯O2	0.85	2.52	3.261 (3)	147
O9—H9A⋯O15	0.85	1.81	2.652 (4)	167
O9—H9B⋯O2	0.84	1.99	2.812 (3)	166

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

Acknowledgments

This work was supported by the Natural Science Foundation of the Education Department of Jiangsu Province (No. 06KJD150208).

supplementary crystallographic information

Comment

We are making a systematic investigation of chiral complexes of Schiff base derived from chiral dipeptides to which little attention has been given, and recently reported a chiral Cu(II)—Sr(II)—Na(I) complex of a Schiff base ligand resulting from the condensation of glycyl-L-tyrosine with N-5-bromosalicylaldehyde (Liu et al., 2004). Herein, we report the synthesis and structure of a Cu(II)—Cd(II) chiral Schiff base complex derived from glycyl-L-leucine and salicylaldehyde.

The asymmetric unit consists of two [CuL]^- anions ([Cu1L]^- and [Cu2L]^-)(L is a Schiff base derived from glycyl-L-leucine and salicylaldehyde), one cation [Cd^II, O9, O10, O11, O12, O13 and O14]²⁺, and two uncoordinated water molecules (O15 and O16) (Fig. 1). [CuL]^- has an approximate square-planar structure. The two crystallographically independent copper-Schiff base anions each have a chiral carbon centre (C10 and C25) with S-configuration. They are related by a non-crystallographic twofold rotation axis parallel to the [0 1 0] direction (Fig. 2). The deprotonated Schiff base ligand is a triple negatively charged quadridentate ONNO chelant, coordinating to the Cu^II ion via one phenolic oxygen, one deprotonated amide nitrogen atom, one imino nitrogen atom and one carboxylate oxygen. The Cu—O and Cu—N bond distances are in the range of 1.878 (2)–1.954 (2) Å and 1.895 (3)–1.927 (3) Å, respectively (Table 1). The best-fit least-squares plane through the four basal and Cu atoms shows these atoms to be nearly coplanar. The Cd^II is coordinated by six aqua ligands with a slightly distorted octahedral geometry. The six Cd—O bonds in the structure are in the range of 2.228 (2)–2.373 (2) Å.

The anions and cations linked by O—H···O hydrogen bonds (Table 2) form well separated columns along the a-axis in the stacking structure of (Fig. 3). The intermolecular and intramolecular hydrogen bonds in the title compound play an important role in the stabilization of the whole structure.

Experimental

Glycyl-L-leucine (5 mmol), salicylaldehyde (5 mmol) and LiOH (10 mmol) were dissolved in MeOH/H₂O (30 ml, v:v = 1:1) and refluxed for 30 min. Then Cu(ClO₄)₂.6H₂O (5 mmol) was added to the solution and the resulting solution was adjusted to the pH 9–11 by using 5 mol.L^-1 NaOH solution. After stirring at room temperature (25 °C) for 1 hr, CdCl₂.6H₂O (2.5 mmol) was added. A violet precipitate was obtained immediately. After stirring for 30 min and then filtered, the precipitate was recrystallized in water. The violet crystals suitable for X-ray diffraction were obtained after 1 week.