Crystal structure of bis[4′-(1,4,7,10-tetraoxa-13- azacyclopentadecan-13-yl)-2,2′:6′,2′′-terpyridine]cobalt(III) tris(perchlorate) methanol monosolvate monohydrate

The title compound, bis[4′-(1,4,7,10-tetraoxa-13-azacyclopentadecan-13-yl)-2,2′:6′,2"-terpyridine]cobalt(III) tris(perchlorate) methanol monosolvate monohydrate, is a novel complex in which the metal centre is hexacoordinated.


Chemical context
Metal complexes with terpyridine derivatives, [M(R-terpy)]X 2 (M = transition metal ions; R-terpy = substituted 2,2 0 :6 0 ,2 00terpyridine; X = anion), have been investigated because of their interesting properties such as magnetic and photochemical characteristics. Cobalt(II) complexes with R-terpy ligands are known as spin-crossover compounds. Previously, we observed the unique spin-transition behavior in [Co(II)(Rterpy) 2 ](BF 4 ) 2 with long-alkylated terpyridine ligands, and showed that the magnetic behaviors are influenced not only by inter-chain interactions between long alkyl chains but also by stacking interactions between terpyridine moieties (Hayami et al., 2011). We suggested that intermolecular interactions play an important role for the magnetic behaviors of metal complexes. Herein we focused on the terpyridine ligand with a crown ether ring, and synthesized the title compound. ISSN 2056-9890

Structural commentary
The asymmetric unit of the title compound consists of one [Co(crown-terpy) 2 ] complex cation, three perchlorate anions, one methanol solvent molecule and one water solvent molecule. The molecular structure of the complex cation is shown in Fig. 1. The cobalt(III) atom is octahedrally coordinated by six nitrogen atoms of two crown-terpy ligands, i.e. an N 6 donor set. The coordination bond lengths are typical of those for low-spin cobalt(III) compounds. The Co-N distances of the central pyridine in the terpyridine unit [1.844 (9) Å ] are shorter than the Co-N distances of the side pyridine in the terpyridine unit [1.910 (10)-1.949 (10) Å ], which induces a pronounced distortion of the CoN 6 octahedron. The three pyridine rings in each crown-terpy ligand are approximately coplanar [maximum deviations 0.102 (15) and 0.088 (12) Å ], and the two mean planes through the three pyridine rings in the complex are nearly perpendicular to each other, making a dihedral angle of 89.95 (17) .

Supramolecular feature
The overall packing of structure is shown in Fig. 2. In the crystal, O-HÁ Á ÁO hydrogen bonds are formed between the water molecule and the complex cation, between the water molecule and the perchlorate anion, and between the methanol molecule and the complex cation (Table 1). Together with these hydrogen bonds, C-HÁ Á ÁO hydrogen bonds connect the four components, forming a three-dimen- A view of the complex cation of the title compound, showing displacement ellipsoids at the 50% probability level. Table 1 Hydrogen-bond geometry (Å , ).

Refinement
Crystal data, data collection and structure refinement details are summarized in Table 2   Hydrogen site location: inferred from neighbouring sites H atoms treated by a mixture of independent and constrained refinement where P = (F o 2 + 2F c 2 )/3 (Δ/σ) max < 0.001

Special details
Geometry. ENTER SPECIAL DETAILS OF THE MOLECULAR GEOMETRY Refinement. Refinement was performed using all reflections. The weighted R-factor (wR) and goodness of fit (S) are based on F 2 . R-factor (gt) are based on F. The threshold expression of F 2 > 2.0 σ(F 2 ) is used only for calculating R-factor (gt).