Chlorido(4′-chloro-2,2′:6′,2′′-terpyridine-κ3 N,N′,N′′)(trifluoromethanesulfonato-κO)zinc(II) acetonitrile monosolvate

The title compound structure is a unique example of a zinc(II) metal center surrounded by a tridentate chloroterpyridine ligand, a chloride and a coordinated trifluoromethanesulfonate in a distorted square-pyramidal geometry.

In the title complex, [Zn(CF 3 O 3 S)Cl(C 15 H 10 ClN 3 )]ÁCH 3 CN, the zinc(II) core is fivefold coordinated by one chloride, one trifluoromethanesulfonate O atom and three terpyridine N atoms in a slightly distorted square-pyramidal geometry. The structure provides a distinct example amongst other zinc(II) 4-chloroterpyridine complexes because of the unusual planarity of the coordinated chloride, the short length of the Zn-N bond opposite to the chloride ligand [1.9572 (15) Å ], and the presence of an elongated  Å ] in the coordinated trifluoromethanesulfonate ion. A molecule of acetonitrile is also found in the asymmetric unit of the title complex.

Structure description
Substituted terpyridines such as 4 0 -chloro-2,2 0 :6 0 ,2 00 -terpyridine continue to be recognized as useful chelating ligands for many transition-metal ions, including platinum(II) (Qin et al., 2019), copper(II) (Choroba et al., 2019), cadmium(II) (Li et al., 2020), and zinc(II) (Li et al., 2019). Metal complexes containing zinc(II) and substituted terpyridines as chelating ligand have been shown to have promising antitumor activity . Our research group interest currently lies in the synthesis of novel terpyridinemetal complexes with potential antitumor activity; as part of our research in this area, herein we describe the synthesis and structure of the title zinc(II) complex.
The asymmetric unit only contains the title compound, with four symmetry-related entities inside each unit cell. The zinc(II) ion shows a distorted square-pryramidal coordination environment defined by a tridentate 4-chloroterpyridine ligand, a chloride, and an oxygen-coordinated trifluoromethanesulfonate (Fig. 1). The angle N2-Zn1-Cl2 data reports of 168.69 (5) is considerably closer to a planar geometry than the reported value (125.6 ) in the only comparable zinc(II) 4-chloroterpyridine structure currently available in the CSD (version 5.41 with update August 2020; Groom et al., 2016;refcode HIVPOS;Huang & Qian, 2008). Another remarkable feature of the structure is that while  and 2.0468 (17) Å , respectively] are well within the values observed in others zinc(II) 4-chloro terpyridine complexes (Huang & Qian, 2008;Dutta et al., 2019;You et al., 2009), the Zn1-N2 bond length, across the chloride, is shorter [1.9572 (15) Å ] and not comparable. The structure also features a coordinated trifluoromethanesulfonate anion that includes an elongated Zn-O bond of 2.3911 (14) Å (Gosiewska et al., 2006). All relevant bonds and angles are presented in Table 1.
The packing diagram reveals stacking of the asymmetric unit in columns along the b axis. These columns form an alternating pattern with the Cl1 atoms facing away from each other while the trifluoromethanesulfonate ions and acetonitrile molecules occupying the space between the stacked zinc(II) 4-chloroterpyridine units. Adjacent columns also alternate directions in the crystal lattice (Fig. 2).

Figure 2
Perspective view of the packing structure of the title complex along the a axis.

Figure 1
The molecular structure of the title compound with displacement ellipsoids drawn at the 50% probability level; H atoms are omitted for clarity.

Refinement
Crystal data, data collection and structure refinement details are summarized in Table 2.

data-1
IUCrData ( where P = (F o 2 + 2F c 2 )/3 (Δ/σ) max = 0.001 Δρ max = 0.48 e Å −3 Δρ min = −0.46 e Å −3 Special details Geometry. All esds (except the esd in the dihedral angle between two l.s. planes) are estimated using the full covariance matrix. The cell esds are taken into account individually in the estimation of esds in distances, angles and torsion angles; correlations between esds in cell parameters are only used when they are defined by crystal symmetry. An approximate (isotropic) treatment of cell esds is used for estimating esds involving l.s. planes.

Fractional atomic coordinates and isotropic or equivalent isotropic displacement parameters (Å 2 )
x y z U iso */U eq