Crystal structure of [3,10-bis(4-fluorophenethyl)-1,3,5,8,10,12-hexaazacyclotetradecane]nickel(II) diperchlorate

A new nickel(II) complex of a hexaazamacrocycle containing 4-flurophenethyl pendant arms was synthesized by metal template condensation in a one-pot reaction of formaldehyde and amines in the presence of nickel(II) ions and its X-ray crystal structure was determined.


Structural commentary
The molecular structure of the title compound is shown in Fig. 1. Both the complex and perchlorate anion display disorder. The Ni II ion lies close by a special position (twofold axis) and the [NiL] 2+ complex occurs in two orientations with fixed occupancies of 0.50. The refinement of this whole-mol-ecule disorder needed additional restraints (see Refinement section). The occupancies of the disordered perchlorate ion are 0.795 (7) and 0.205 (7). The nickel(II) ion is coordinated to the four nitrogens N2, N3, N2 0 and N3 0 , and the complex has a square-planar coordination geometry. The 14-membered ring skeleton adopts the thermodynamically most stable trans-III configuration with R,R,S,S chirality of the four coordinated nitrogen atoms (Barefield, 2010). The ligand L of the complex has two 4-fluorophenethyl pendant arms attached to the two uncoordinated nitrogens (N1 and N1 0 ) of the 14-membered 1,3,5,8,10,12-hexaazacyclotetradecane ring skeleton. The 4-fluorophenethyl pendants are positioned above and below the square coordination plane. The sixmembered chelate rings adopt a chair conformation and the five-membered chelate rings assume a gauche conformation.

Supramolecular features
There are several N-HÁ Á ÁA (A = O) as well as C-HÁ Á ÁA (A = O or F) hydrogen bonds in the crystal packing of Table 1 Selected geometric parameters (Å , ).
[NiL](ClO 4 ) 2 . Hydrogen-bonding interactions between N-H or C-H groups of the ligand L and perchlorate oxygen atoms are summarized in Table 2 and illustrated in Fig. 2. In addition, fluorine atom F1 in one of the pendant phenyl groups of the macrocycle is involved in an intermolecular interaction with hydrogen H4A of a neighboring molecule (Table 2 and

Synthesis and crystallization
A well-known one-pot reaction of template condensation was used for the preparation of the title complex (Salavati-Niasari & Rezai-Adaryani, 2004;Min & Suh, 2001;Kang et al., 1999). 98% Ethylenediamine (1.1 ml, 16mmol), 99% 4-fluorophenethylamine (2.1 ml, 16 mmol), and 95% paraformaldehyde (1.44 g, 48 mmol) were slowly added to a stirred solution of 98% nickel(II) acetate tetrahydrate (2.0 g, 8.0 mmol) in 50 ml of methanol. The solution was heated under reflux for 24 h and then cooled to room temperature. The solution was filtered, concentrated HClO 4 was added to the filtrate, adjusting pH of the solution to 4, and it was kept in a refrigerator until a yellow-colored precipitate was formed. The product was filtered, washed with methanol, and dried in air.
Single crystals for X-ray crystallography were obtained by recrystallization from hot water.

Refinement
Crystal data, data collection and structure refinement details are summarized in Table 3. H atoms were positioned geometrically and allowed to ride on their respective parent atoms [C-H = 0.93 Å (CH, aromatic), 0.97 Å (CH 2 ) and N-H = 0.98 Å (NH 2 ), and U iso (H) = 1.2U eq (C) or U iso (H) = 1.2U eq (N)]. The refinement of the whole-molecule disorder employed the following constraints and restraints in SHELXL: (1) occupancy factors were set at 0.50, (2) the two chemically equivalent halves of the complex were restrained to be similar using the 'SAME' command, (3) the fluorinated benzene rings were given a weak 'FLAT' restraint, (4) Ni1 required a strong 'ISOR' restraint and (5) displacement factors for atom pairs related about the special position were constrained to be equal (EADP).
The perchlorate anion is disordered over two sets of atomic sites with occupancy ratios of 0.795 (7):0.205 (7).   Data collection: SMART (Bruker, 2002); cell refinement: SAINT (Bruker, 2002); data reduction: SAINT (Bruker, 2002); program(s) used to solve structure: SHELXS97 (Sheldrick, 2008); program(s) used to refine structure: SHELXL2018/3 (Sheldrick, 2015); molecular graphics: ORTEP-3 for Windows (Farrugia, 2012), Mercury (Macrae et al., 2020); software used to prepare material for publication: WinGX (Farrugia, 2012). 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.