(5,10,15,20-Tetraphenylporphyrinato-κ4 N)cobalt(II)–18-crown-6 (1/1)

The asymmetric unit of the title compound, [Co(C44H28N4)]·C12H24O6, contains one half of a CoII(TPP) (TPP is tetraphenylporphyrin) complex and one half of an 18-crown-6 molecule of crystallization, both lying on inversion centers. The CoII(TPP) complex exhibits a nearly planar conformation of the porphyrinate core [maximum deviation = 0.069 (2) Å] with an average Co—N distance of 1.971 (4) Å. The distance between the Co atom and the closest O atom of the 18-crown-6 molecule is 2.533 (2) Å, indicating a short non-bonded contact between the Co atom and the crown ether molecule. An ethylene group of the 18-crown-6 molecule is disordered over two sites with occupancies of 0.565 (7) and 0.435 (7).


Experimental
Crystal data [Co(C 44

Comment
Cobalt atom in metalloporphyrines is commonly used as a qualitatively acceptable substitute for iron atom in high-spin five-coordinate hemes of deoxyhemoglobin and in the low-spin oxygenated hemes of oxyhemoglobin. The metalation of a porphyrin by cobalt (using CoCl 2 . 6H 2 O salt) yields the stable [Co II (Porph)] (Porph = porphyrin) complex used as starting material in the preparation of five and six-coordinated Co(II) and Co(III) metalloporphyrines (Sanders et al., (2000). In the Cambridge Structural Database (CSD, version 5.31;Allen 2002) there are three structures of tetra-coordinated cobalt(II) tetraphenylporphyrin (TPP) complexes: IKUDOH (Konarev et al., 2003), IXIKIJ (Konarev et al., 2004) andTPORCP12 (Nascimento et al., 2007). Herein we report the struture of the title compound,(I), which has been prepared in our laboratory.
The asymmetric unit of (I), contains one half [Co II (TPP)] complex and one half crystallographically independent 18crown-6 molecule of crystallization both lying on inversion centers (Fig. 1).
The distance between the cobalt(II) ion and the symmetry related O1 and O1' atoms ( Fig. 2) et al., 2002). This indicates that in (I) there is a short non-bonded contact between the cobalt ion and the crown ether molecule.
It has been noticed that there is a relationship between the ruffling of the porphyrinato core and the mean equatorial Co(II)-N p distance (N p = pyrrol N atom); the porphyrinato core is ruffled as the Co-N p distance decreases, (Iimura et al., 1988). Thus, the average distance Co-N p in (I), 1.971 (4) Å, is longer than those of the three other reported [Co II (TPP)] structures quoted above [1.923 (3) -1.969 (6) Å]. The porphyrin core in (I) presents a planar conformation with maximum and minimum deviations from the C 20 N 4 least-squares plane of 0.069 (2) and -0.068 (2) Å for C6 and C8 atoms, respectively, while the Co 2+ cation is basically in the porphyrin plane with a Co-C t distance of 0.004 (1) Å (where C t is the center of the C 20 N 4 plane).
supplementary materials sup-2 Refinement All H atoms were placed in geometrically idealized positions (C-H = 0.93-0.97 Å) and constrained to ride on their parent atoms, with U(H) = 1.2U eq (C). An ethylene group [C24 -C25] of the 18-crown-6 molecule was disordered over two sites with occupancies of 0.565 (7) and 0.435 (7). For this fragment, some anisotropic displacement ellipsoids were rather elongated which led us to use the SIMU/ISOR restraints (McArdle, 1995, Sheldrick, 2008. Alerts B and C for short intramolecular contacts H···H may be explained by the fact that C24 and C25 carbon atoms are disordered. Fig. 1. A view of the structure of (I), with the atom-numbering scheme. Unlabeled atoms are related by an inversion center to the labeled atoms. Displacement ellipsoids are drawn at 50%. The H atoms and the minor positions of the disordered C24 and C25 atoms have been omitted for clarity. Fig. 2. A unit-cell packing of (I). The short non-bonded contacts between the cobalt and the symmetry related O1 and O1' atoms of the two closest crown ether molecues, are drawn by dashed lines. The H atoms and the minor positions of the disordered C24 and C25 atoms have been omitted for clarity.

Special details
Geometry. All s.u.'s (except the s.u. in the dihedral angle between two l.s. planes) are estimated using the full covariance matrix. The istically about twice as large as those based on F, and R-factors based on ALL data will be even larger.