{μ-trans-N,N′-Bis[2-(2-hydroxy­ethyl­amino)eth­yl]oxamidato(2−)}bis­[picrato­nickel(II)]

Chunliang Tian

doi:10.1107/S1600536809052933

. 2009 Dec 16;66(Pt 1):m71. doi: 10.1107/S1600536809052933

{μ-trans-N,N′-Bis[2-(2-hydroxyethylamino)ethyl]oxamidato(2−)}bis[picratonickel(II)]

Chunliang Tian ^a,^*

PMCID: PMC2980076 PMID: 21579966

Abstract

The title complex, [Ni₂(C₆H₂N₃O₇)₂(C₁₀H₂₀N₄O₄)], contains a centrosymmetric binuclear unit in which the oxamide ligand (located on a centre of symmetry) acts in a bis-tetradentate fashion and the picrate anion binds to nickel(II) in a bidentate mode. The Ni^II atom displays a distorted octahedral coordination with axial elongation. The binuclear molecules are linked by intermolecular N—H⋯O, O—H⋯O and C—H⋯O hydrogen bonds into a two-dimensonal supramolecular network extending parallel to (100).

Related literature

For background to oxamido compounds and their complexes, see: Ruiz et al. (1999 ▶); Ojima & Nonoyama (1988 ▶).

Experimental

Crystal data

[Ni₂(C₆H₂N₃O₇)₂(C₁₀H₂₀N₄O₄)]
M _r = 833.93
Triclinic,
a = 7.7893 (16) Å
b = 8.1405 (16) Å
c = 12.417 (3) Å
α = 98.00 (3)°
β = 99.00 (3)°
γ = 94.36 (3)°
V = 766.2 (3) Å³
Z = 1
Mo Kα radiation
μ = 1.33 mm⁻¹
T = 298 K
0.19 × 0.14 × 0.10 mm

Data collection

Bruker SMART CCD diffractometer
Absorption correction: multi-scan (SADABS; Sheldrick, 1996 ▶) T _min = 0.786, T _max = 0.879
4040 measured reflections
2703 independent reflections
2233 reflections with I > 2σ(I)
R _int = 0.015

Refinement

R[F ² > 2σ(F ²)] = 0.035
wR(F ²) = 0.087
S = 1.23
2703 reflections
235 parameters
1 restraint
H-atom parameters constrained
Δρ_max = 0.39 e Å⁻³
Δρ_min = −0.30 e Å⁻³

Data collection: SMART (Bruker, 1998 ▶); cell refinement: SAINT (Bruker, 1998 ▶); data reduction: SAINT; program(s) used to solve structure: SHELXS97 (Sheldrick, 2008 ▶); program(s) used to refine structure: SHELXL97 (Sheldrick, 2008 ▶); molecular graphics: SHELXTL (Sheldrick, 2008 ▶); software used to prepare material for publication: SHELXL97 and PLATON (Spek, 2009 ▶).

Supplementary Material

Crystal structure: contains datablocks I, global. DOI: 10.1107/S1600536809052933/si2223sup1.cif

e-66-00m71-sup1.cif^{(20.7KB, cif)}

Structure factors: contains datablocks I. DOI: 10.1107/S1600536809052933/si2223Isup2.hkl

e-66-00m71-Isup2.hkl^{(132.7KB, hkl)}

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

Table 1. Selected bond lengths (Å).

N1—Ni1	1.903 (3)
N2—Ni1	2.032 (3)
O1—Ni1	1.991 (3)
O2—Ni1	2.537 (3)
O3—Ni1	1.942 (2)
O4—Ni1	2.561 (3)

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

D—H⋯A	D—H	H⋯A	D⋯A	D—H⋯A
N2—H2C⋯O7ⁱ	0.91	2.15	3.054 (4)	171
O2—H2⋯O1ⁱⁱ	0.86	2.34	3.084 (4)	145
C10—H10⋯O5ⁱⁱⁱ	0.93	2.49	3.319 (5)	149

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

Acknowledgments

We acknowledge the financial support of the Science Foundation of Shandong.

supplementary crystallographic information

Comment

Oxamido compounds and their complexes have been investigated extensively (Ruiz et al., 1999) by virtue of their bioactivities and the versatile bridging function (Ojima & Nonoyama, 1988). We selected N,N'-bis(3-aminopropyl)oxamide as a bridging ligand and picrate as a terminal group to synthesize a new binuclear nickel(II) compound, (I).

The title compound, (I) (Fig. 1), is a binuclear nickel(II) complex containing a total of 52 non-H atoms. Two terminal picrate ligands and a µ₃-trans-oxamidato bridge with an inversion centre at the mid-point of the C—C bond of the oxamide group. The geometry of each nickel(II) atom is distorted octahedral. For the Ni1, atoms O2 and O4 are in axial positions. The equatorial plane is composed of three atoms from the oxamide bridge (N1, N2, and O1) and the phenolic oxygen atom (O3) from the picrate ligand. The maximum displacement of the four atoms from the equatorial plane is 0.1117 (15) Å at N1, and the nickel(II) atom lies 0.0524 (8) Å out of the plane. The Ni—N bond lenghts (Table 1) are 1.903 (3) and 2.032 (3)Å, whereas the bond lengths of Ni1—O2 and Ni1—O4 are relatively long and can be considered as a (4+1+1) coordination. As a terminal group, the picrate anion assumes a bidentate mode, forming a six-membered chelate ring on the nickel(II) ion. The dihedral angle between the benzyl ring of the picrate ion and the equatorial plane is 88.28 (3)°.

The crystal structure is stabilized by hydrogen bonding. As shown in Fig. 2, a two-dimensional infinite network is formed via the N—H···O and O—H···O intermolecular hydrogen bonds. The adjacent layers are further connected by non-classical C—H···O hydrogen bonding contacts (Table 2) to form a two-dimensional supramolecular architecture in a zig-zag fashion parallel to the b,c plane (Fig. 2).

Experimental

To a stirred methanol solution (10 ml) containing Ni(pic)₂^.6H₂O (0.1255 g, 0.2 mmol) was added dropwise a ethanol solution (10 ml) of N,N'-bis(N-hydroxyethylaminoethyl)oxamide (0.0262 g, 0.1 mmol) and piperidine (0.0170 g, 0.2 mmol) at room temperature. The mixture was stirred quickly at 323 K for 8 h. The resulting solution was filtered and the filtrate was kept at room temperature. Green crystals suitable for X-ray analysis were obtained from the filtrate by slow evaporation for about two weeks.Yield, 46%, analysis, calculated for C₂₂H₂₄N₁₀O₁₈Ni₂: C 31.69, H, 2.90; N 16.80%; found: C 31.75, H 2.91, N, 16.82%.