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

The title compound, C34H28N6O2, has an inversion centre located at the mid-point of the central C—C bond of the diether bridging unit. The central pyridine rings of the terpyridyl units and the diether chain are co-planar: the maximum deviation from the 18-atom mean plane defined by the bridging unit and the central pyridyl ring is for the pyridyl N atom which sits 0.055 (1) Å above the plane. The dihedral angles between the terminal pyridine rings with this plane are 10.3 (1) and 37.6 (1)°, repectively. In the crystal, weak C—H⋯N interactions link the molecules into infinite chains parallel to the a axis.

The title compound, C 34 H 28 N 6 O 2 , has an inversion centre located at the mid-point of the central C-C bond of the diether bridging unit. The central pyridine rings of the terpyridyl units and the diether chain are co-planar: the maximum deviation from the 18-atom mean plane defined by the bridging unit and the central pyridyl ring is for the pyridyl N atom which sits 0.055 (1) Å above the plane. The dihedral angles between the terminal pyridine rings with this plane are 10.3 (1) and 37.6 (1) , repectively. In the crystal, weak C-HÁ Á ÁN interactions link the molecules into infinite chains parallel to the a axis.

Experimental
We wish to thank the University of KwaZulu-Natal for supporting this research by providing both funding and facilities.

Comment
The title compound is one in a series of ligands developed in an attempt to harness multifunctional activity. Upon coordination to platinum(II) these complexes should be able to covalently bind 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 triclinic space group P-1, with a half molecule in the asymmetric unit and Z = 1. The two halves of the ligand are related by crystallographically imposed inversion symmetry. The inversion centre is located at the mid-point of the di-ether linkage unit. The three pyridine rings adopt a trans, trans conformation as observed in the parent 4'-chloro-2,2':6',2''-terpyridine (Beves et al., 2006) and in uncoordinated terpy ligands in general.
The central pyridine rings of the terpy ligands are in the same plane as the bridging di-ether chain. The terminal pyridine rings of the terpyridine ligand are, however canted relative to the central pyridine ring. The C9-C10-C11-N3 torsion angle is 35.4 (1)°, while the C7-C2-C1-N2 torsion angle is 7.1 (1)° (refer to Figure 1 for the atom numbering scheme). The large torsion angle of the pyridine ring containing N3 is seemingly to allow for hydrogen bonding between the pyridine nitrogen atom N3 and the H13 hydrogen atom of an adjacent molecule (Table 1) . This interaction links the molecules into a one-dimensional chain (Figure 2) along the a-axis direction. There is no indication of meaningful π···π or C-H···π interactions in the crystal, 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 andConstable et al., 2005). Butanediol (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 of were grown by slow liquid diffusion of n-hexane into a chloroform solution of the compound.

Refinement
All non-hydrogen atoms were located in the difference Fourier map and refined anisotropically. The positions of all hydrogen atoms were calculated using the standard riding model of SHELXL97. with C-H(aromatic)and C-H (methylene)distances of 0.93 Å and U iso = 1.2 U eq . Fig. 1. The molecular structure of the title compound. Displacement ellipsoids are drawn at the 40% probability level. bsorption correction: multi-scan (Blessing, 1995) h = −10→9