μ-Acetato-μ-(5-chloro-2-{1,3-bis[2-(5-chloro-2-oxidobenzylideneamino)ethyl]imidazolidin-2-yl}phenolato)-bis[methanolnickel(II)] methanol monosolvate monohydrate

Ahmed Raza Khan; Yohannes Tesema; Ray J Butcher; Yilma Gultneh

doi:10.1107/S1600536811032727

. 2011 Aug 17;67(Pt 9):m1264–m1265. doi: 10.1107/S1600536811032727

μ-Acetato-μ-(5-chloro-2-{1,3-bis[2-(5-chloro-2-oxidobenzylideneamino)ethyl]imidazolidin-2-yl}phenolato)-bis[methanolnickel(II)] methanol monosolvate monohydrate

Ahmed Raza Khan ^a, Yohannes Tesema ^a, Ray J Butcher ^a,^*, Yilma Gultneh ^a

PMCID: PMC3200742 PMID: 22064868

Abstract

The crystal structure shows that the title compound, [Ni₂(CH₃CO₂)(C₂₇H₂₄Cl₃N₄O₃)(CH₄O)₂]·CH₃OH·H₂O, contains [Ni₂ L(OAc)(CH₃OH)₂] molecules in the unit cell {H₃ L = 5-chloro-2-{1,3-bis[2-(5-chloro-2-oxidobenzylideneimino)-ethyl]imidazolidin-2-yl}phenolate} with water and methanol as solvates. The title compound is a neutral dinuclear compound, in which the L ³⁻ Schiff base acts as a heptadentate ligand, using each one of its N₂O compartments to coordinate a nickel atom. The acetate anion bridges the two nickel atoms via one O while the distorted octahedral coordination sphere for each nickel atom is completed by a coordinated methanol ligand. One of the coordinated methanol ligands is involved in an intramolecular hydrogen bond to the uncoordinated O atom of the bridging acetate ligand while the other forms a hydrogen bond with the methanol solvate. The solvate water molecule forms strong hydrogen bonds to both terminal phenolato O atoms. The methanol solvate molecule also forms a hydrogen bond with the water solvate molecule.

Related literature

For dinuclear nickel compounds containing ligands with a predefined ground state, see: Fondo et al. (2005 ▶, 2007 ▶, 2009 ▶); Fondo, Garcia-Deibe et al. (2006 ▶); Fondo, Ocampo et al. (2006 ▶); Lu et al. (2007 ▶); Paital et al. (2007 ▶, 2009 ▶). For density functional theory (DFT) calculations, see: Fondo et al. (2005 ▶).

Experimental

Crystal data

[Ni₂(C₂H₃O₂)(C₂₇H₂₄Cl₃N₄O₃)(CH₄O)₂]·CH₄O·H₂O
M _r = 849.46
Orthorhombic,
a = 16.684 (2) Å
b = 16.042 (2) Å
c = 13.7868 (19) Å
V = 3690.1 (9) Å³
Z = 4
Mo Kα radiation
μ = 1.29 mm⁻¹
T = 173 K
0.45 × 0.40 × 0.20 mm

Data collection

Bruker SMART 1000 CCD area-detector diffractometer
Absorption correction: multi-scan (SADABS; Sheldrick, 2003 ▶) T _min = 0.685, T _max = 1.000
23326 measured reflections
8737 independent reflections
7189 reflections with I > 2σ(I)
R _int = 0.037

Refinement

R[F ² > 2σ(F ²)] = 0.033
wR(F ²) = 0.064
S = 0.97
8737 reflections
464 parameters
4 restraints
H atoms treated by a mixture of independent and constrained refinement
Δρ_max = 0.34 e Å⁻³
Δρ_min = −0.23 e Å⁻³
Absolute structure: Flack (1983 ▶), 3935 Friedel pairs
Flack parameter: 0.017 (8)

Data collection: SMART (Bruker, 2000 ▶); cell refinement: SMART; data reduction: SAINT-Plus (Bruker, 2000 ▶); 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: SHELXTL.

Supplementary Material

Crystal structure: contains datablock(s) I, global. DOI: 10.1107/S1600536811032727/jj2099sup1.cif

e-67-m1264-sup1.cif^{(36KB, cif)}

Structure factors: contains datablock(s) I. DOI: 10.1107/S1600536811032727/jj2099Isup2.hkl

e-67-m1264-Isup2.hkl^{(427.4KB, hkl)}

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

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

D—H⋯A	D—H	H⋯A	D⋯A	D—H⋯A
O1MA—H1MK⋯O2AA	0.84	1.77	2.586 (3)	162
O1MA—H1MK⋯O1AA	0.84	2.66	3.029 (2)	108
O1W—H1W1⋯O1A	0.82 (2)	1.86 (2)	2.679 (3)	175 (4)
O1W—H1W2⋯O1B	0.81 (2)	1.91 (2)	2.708 (3)	174 (3)
O1M—H1M⋯O1Wⁱ	0.84	1.74	2.577 (3)	170
O1MB—H1MJ⋯O1M	0.84	1.83	2.658 (3)	167

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

Acknowledgments

RJB wishes to acknowledge the NSF–MRI program (grant No. CHE-0619278) for funds to purchase the diffractometer. ARK and YT wish to acknowledge the Howard University Graduate School of Arts and Sciences for the award of a Teaching Assistanceship.

supplementary crystallographic information

Comment

Nickel complexes of the compartmental triprotic heptadentate ligand, 2-hydroxyphenyl)-1,3-bis[4-(2- hydroxyphenyl)-3-azabut- 3-enyl]-1,3-imidazolidine and its derivatives have been of interest for their ability to give rise to dinuclear compounds with a predefined ground state (Fondo et al., 2005, 2007, 2009; Fondo, Garcia-Deibe et al., 2006; Fondo, Ocampo et al., 2006; Lu et al., 2007; Paital, et al., 2007, 2009). Density functional theory (DFT) calculations demonstrated that the Schiff base provides an NCN bridge between the metal ions that helps to mediate the ferromagnetic exchange (Fondo, et al., 2005). Consequently, the use of suitable cross-linking ligands between the dinuclear units could be a route to produce complexes of higher nuclearity, with all of the unpaired electrons aligned parallel to each other. The type of complex obtained depends on the synthesis conditions as the coordination environment about the metals is usually completed by coordinating solvent molecules.

The crystal structure shows that C₃₂H₄₁Cl₃N₄Ni₂O₉, (I), contains [Ni₂L(OAc)(CH₃OH)₂] molecules in the unit cell (H₃L = 2-(5-chloro-2-hydroxyphenyl)-1,3-bis[4-(5-chloro-2- hydroxyphenyl)-3-azabut-3-enyl]-1,3-imidazolidine) with water and methanol as solvates. (I) is a neutral dinuclear compound, where the L^3- Schiff base acts as a compartmental trianionic heptadentate ligand, using each one of its N₂O compartments to coordinate a nickel atom. Thus, the metal atoms are joined to one terminal phenol oxygen (O1A, O1B), an iminic nitrogen (N1A, N1B), and an aminic nitrogen atom (N2A, N2B), with the aminic NCN group (N2A—C7—N2B) acting as a bridge between both nickel ions. In addition, the nickel centers are linked by the endogenous phenolate oxygen atom (O1) of the central ligand arm and by an exogenous bridging monodentate acetate group (O1AA). This gives rise to a nearly planar Ni₂O₂ metallacycle, with an intramolecular Ni—Ni distance of 3.1078 (6) Å. The coordination spheres of the nickel atoms are completed by methanol molecules. Therefore, the metal centers are hexacoordinated in a N₂O₄ environment, with an octahedral geometry. The Ni—O and Ni—N distances, as well as the angles about the metal atoms, show quite regular polyhedra around the central ions, with both the Ni—O_phenol—Ni and Ni—O_acetate—Ni angles being similar [97.98 (7)° and 97.37 (8)°, respectively]. There are similar structures reported in the literature which differ only in the nature of the coordinating solvent (H₂O) and solvate molecules (H₂O, CH₃CN) in the lattice (Fondo, Ocampo et al., 2006).

One of the coordinated methanol ligands is involved in an intramolecular hydrogen bond to the uncoordinated O atom (O2AA) of the bridging acetate ligand while the other forms a hydrogen bond with the methanol solvate. The solvate water molecule forms strong hydrogen bonds to both O1A and O1B. The methanol solvate molecule also forms a hydrogen bond with the water solvate molecule.

Experimental

For the synthesis of the ligand (H₃L) methanol solutions of triethylenetetramine and 5-chlorosalicylaldehyde were mixed in 1:3 mol ratio. After heating at 60° C for a few minutes, ether was added to this mixture, and the yellow crystals were separated, filtered and recrystallized from methanol solution. Mp 103–104° C. For synthesis of the complex, to a stirred methanol solution (25 ml) of [Ni(O₂CCH₃)₂]4H₂O (1.5 g, 2.67 mmol) was added 1.33 g (5.35 mmol) of the ligand H₃L. Slow evaporation of the green filtrate overnight yielded green cystals suitable for X-ray analysis in 75% yield.