1,6-Bis[(2,2′:6′,2′′-terpyridin-4′-yl)­oxy]hexa­ne

Varvara I Nikolayenko; Matthew P Akerman; Craig D Grimmer; Desigan Reddy

doi:10.1107/S1600536812029017

. 2012 Jun 30;68(Pt 7):o2272–o2273. doi: 10.1107/S1600536812029017

1,6-Bis[(2,2′:6′,2′′-terpyridin-4′-yl)oxy]hexane

Varvara I Nikolayenko ^a,^*, Matthew P Akerman ^a, Craig D Grimmer ^a, Desigan Reddy ^a

PMCID: PMC3394054 PMID: 22798919

Abstract

The molecule of the title compound, C₃₆H₃₂N₆O₂, lies about an inversion center, located at the mid-point of the central C—C bond of the diether bridge. The terminal pyridine rings form dihedral angles of 4.67 (7) and 26.23 (7)° with the central ring. In the crystal, weak C—H⋯N and C—H⋯O interactions link the molecules into a three-dimensional network.

Related literature

For the structure of the unsubstituted 2,2′:6′,2"-terpyridine, see: Bessel et al. (1992 ▶). For the structure of the precursor to the title compound, 4′-chloro-2,2′:6′,2"-terpyridine, see: Beves et al. (2006 ▶). For the structure of the 1,4-bis[(2,2′:6′,2"-terpyridin-4′-yl)oxy]-butane, see: Akerman et al. (2011 ▶). For a full review of functionalized 2,2′:6′,2"-terpyridine complexes, see: Fallahpour (2003 ▶); Heller & Schubert (2003 ▶). For a comprehensive summary of platinum(II) terpyridine complexes, see: Newkome et al. (2008 ▶). For the structure of bis(2,2′:6′,2"-terpyridyl)ether, see: Constable et al. (1995 ▶). For the structure of related bis(terpyridine) compounds, linked by an alkoxy spacer, see: Constable et al. (2006 ▶). For the synthetic procedure, see: Constable et al. (2005 ▶); Van der Schilden (2006 ▶).

Experimental

Crystal data

C₃₆H₃₂N₆O₂
M _r = 580.7
Orthorhombic,
a = 15.139 (5) Å
b = 11.428 (5) Å
c = 16.760 (5) Å
V = 2899.6 (18) Å³
Z = 4
Mo Kα radiation
μ = 0.09 mm⁻¹
T = 100 K
0.40 × 0.20 × 0.20 mm

Data collection

Oxford Diffraction Xcalibur 2 CCD diffractometer
Absorption correction: multi-scan (Blessing, 1995 ▶) T _min = 0.967, T _max = 0.983
20354 measured reflections
2859 independent reflections
2098 reflections with I > 2σ(I)
R _int = 0.064

Refinement

R[F ² > 2σ(F ²)] = 0.038
wR(F ²) = 0.100
S = 0.94
2859 reflections
199 parameters
H-atom parameters constrained
Δρ_max = 0.17 e Å⁻³
Δρ_min = −0.26 e Å⁻³

Data collection: CrysAlis CCD (Oxford Diffraction, 2008 ▶); cell refinement: CrysAlis CCD; data reduction: CrysAlis RED (Oxford Diffraction, 2008 ▶); program(s) used to solve structure: SHELXS97 (Sheldrick, 2008 ▶); program(s) used to refine structure: SHELXL97 (Sheldrick, 2008 ▶); molecular graphics: ORTEP-3 (Farrugia, 1999 ▶); software used to prepare material for publication: publCIF (Westrip, 2010 ▶).

Supplementary Material

Crystal structure: contains datablock(s) I, global. DOI: 10.1107/S1600536812029017/yk2063sup1.cif

e-68-o2272-sup1.cif^{(22.2KB, cif)}

Structure factors: contains datablock(s) I. DOI: 10.1107/S1600536812029017/yk2063Isup2.hkl

e-68-o2272-Isup2.hkl^{(137.6KB, hkl)}

Supplementary material file. DOI: 10.1107/S1600536812029017/yk2063Isup3.cml

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

Table 1. Short intermolecular contacts (Å, °).

D—H⋯A	D—H	H⋯A	D⋯A	D—H⋯A
C15—H15⋯Oⁱ	0.95	2.65	3.575 (2)	164
C1—H1⋯N3ⁱⁱ	0.95	2.71	3.654 (2)	174
C4—H4⋯N1ⁱⁱⁱ	0.95	2.65	3.402 (2)	136
C2—H2⋯Oⁱⁱ	0.95	2.69	3.627 (2)	168

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

Acknowledgments

We wish to thank the Univeristy of Kwazulu-Natal for supporting this research by providing both funding and facilities.

supplementary crystallographic information

Comment

The title compound is the second in a series of ligands developed in an effort to harness multifunctional activity. Coordination of these ligands to platinum(II) should enable covalent binding of DNA through both metal centres, thus increasing the number of adducts formed. Furthermore the presence of the flexible diol derived linkage will provide the complex with the potential to engage in long range interactions with DNA.

The ligand crystallized in the orthorhombic space group Pbca, with a half molecule in the asymmetric unit and Z = 4. Crystallographically imposed inversion symmetry relates two halves of the ligand. The inversion center is located at the mid-point of the diol linkage. The three pyridine rings adopt a trans, trans conformation. The same configuration is observed in the parent 4'-chloro-2,2': 6',2''- terpyridine (Beves et al., 2006) and is a common feature of uncoordinated terpyridine ligands in general (Akerman et al., 2011; Bessel et al., 1992).

The central pyridine ring of the terpyridine fragment lie in the same plane as the bridging chain. The terminal pyridine rings are, however, canted relative to the central ring. The C7–C6–C5–N1 torsion angle is -25.8 (2)°, while the C9–C10–C11–N3 torsion angle is 4.9 (2)° (Fig. 1). The large torsion angle formed by one of terminal pyridine groups with the central ring is seemingly to allow for interaction between the pyridine N1 atom and the hydrogen atom H4 of an adjacent molecule, with the distance of 2.65 Å. There are also other short contacts C—H···O and C—H···N, ranging from 2.65 to 2.71 Å. These contacts link the molecules into a herringbone pattern (Figure 2). There is no indication of meaningful π··· π or C–H··· π interactions in the lattice, which are often observed in terpyridine structures (Beves et al. 2006).

Experimental

The title compound was prepared by an adaptation of a previously described method (Van der Schilden, 2006; Constable et al., 2005). Hexanediol (1.13 mmol) was added to a suspension of ground potassium hydroxide (6.69 mmol) in DMSO (30 ml). The solution was heated to reflux for 1 h after which 4'-chloro-2,2':6',2''-terpyridine (2.23 mmol) was added. The mixture was again brought to reflux for an additional 24 h. After cooling to room temperature, the brown mixture was added to cold water (100 ml). The resulting off-white precipitate was filtered, rinsed with cold ethanol and air dried. Single crystals were grown by slow liquid diffusion of n-hexane into a chloroform solution of the compound.