Chlorido(pyridine-κN)(5,10,15,20-tetraphenylporphyrinato-κ4 N)cobalt(III) chloroform hemisolvate

In the title complex, [CoCl(C44H28N4)(C5H5N)]·0.5CHCl3 or [CoIII(TPP)Cl(py)]·0.5CHCl3 (where TPP is the dianion of tetraphenylporphyrin and py is pyridine), the average equatorial cobalt–pyrrole N atom bond length (Co—Np) is 1.958 (7) Å and the axial Co—Cl and Co—Npy distances are 2.2339 (6) and 1.9898 (17) Å, respectively. The tetraphenylporphyrinate dianion exhibits an important nonplanar conformation with major ruffling and saddling distortions. In the crystal, molecules are linked via weak C—H⋯π interactions. In the difference Fourier map, a region of highly disordered electron density was estimated using the SQUEEZE routine [PLATON; Spek (2009 ▶), Acta Cryst. D65, 148–155] to be equivalent to one half-molecule of CHCl3 per molecule of the complex.

In the title complex, [CoCl(C 44 H 28 N 4 )(C 5 H 5 N)]Á0.5CHCl 3 or [Co III (TPP)Cl(py)]Á0.5CHCl 3 (where TPP is the dianion of tetraphenylporphyrin and py is pyridine), the average equatorial cobalt-pyrrole N atom bond length (Co-N p ) is 1.958 (7) Å and the axial Co-Cl and Co-N py distances are 2.2339 (6) and 1.9898 (17) Å , respectively. The tetraphenylporphyrinate dianion exhibits an important nonplanar conformation with major ruffling and saddling distortions. In the crystal, molecules are linked via weak C-HÁ Á Á interactions. In the difference Fourier map, a region of highly disordered electron density was estimated using the SQUEEZE routine [PLATON; Spek (2009), Acta Cryst. D65, 148-155] to be equivalent to one half-molecule of CHCl 3 per molecule of the complex.
Concerning the 1 H NMR of cobalt metalloporphyrins, it has been noticed that the paramagnetic starting material  (Shirazi Goff, 1982). Complex (I) presents a peak at 9.13 p.p.m. attributed to the β-pyrr protons, which is an indication that our derivative is a diamagnetic cobalt(III) meso-porphyrin species.
We report herein on the molecular structure of the title compound, a mixed-ligand py-Co(III)-Cl tetraphenylporphyrin species [Co III (TPP)Cl(py)]. In this complex, the cobalt is coordinated to the four N atoms of the porphyrin ring, the chloride ion and the nitrogen atom of the pyridine axial ligand (Fig. 1) (2)-2.043 (7) Å]. It has been noticed that there is a relationship between the ruffling of the porphyrinato core and the mean equatorial Co-N p distance; the porphyrinato core is ruffled as the Co-N p distance decreases (Iimuna et al., 1988). Thus, for the very ruffled structure [Co II (TPP)] (Konarev et al., 2003) the Co-N p bond length value is 1.923 (4) Å while the practically planar porphyrin core of the ion complex [Co III (OEP)(NO 2 ) 2 ] -(OEP is the octaethylporphyrin; Ali et al., 2011) presents a Co-N p distance of 1.988 (2) Å. Therefore, the Co-N p distance in the title complex [1.958 (2) Å] is normal for a cobalt ruffled TPP species. On the other hand Normal Structural Decomposition (NSD) calculations (Jentzen et al., 1997) confirm the unusually important deformation of the porphyrin supplementary materials sup-2 Acta Cryst. (2012). E68, m1104-m1105 core with a major ruffling and saddling distortions of 52% and 39%, respectively.

Experimental
[Co II (TPP)] (100 mg, 0.149 mmol) (Madure & Scheidt 1976) and (150 mg, 1.441 mmol) of NaHSO 3 and (18 ml, 0.223 mmol) of pyridine in 25 ml of chloroform were stirred overnight at room temperature. The color of the solution turns from red-orange to dark-red and the final product is the title complex [Co III (TPP)Cl(py)].0.5(CHCl 3 ). This means that the NaHSO 3 reagent did not react with [Co II (TPP)] and that the Clanion comes from the chlorinated solvent. This is expected given the high affinity of chloride for the cobalt ion. Crystals of the title compound were grown by diffusion of hexanes into a chloroform solution of the title compound.

Refinement
Hydrogen atoms were placed in calculated positions and refined as riding atoms: C-H = 0.95 Å with U iso (H) = 1.2 U eq (C). In a final difference Fourier map highly disordered electron density occupying two cavities of ca 389 Å 3 each was observed. This residual electron density was difficult to model and therefore, the SQUEEZE routine in PLATON (Spek, 2009) was used to eliminate this contribution of the electron density in the solvent region from the intensity data. The solvent-free model was employed for the final refinement. It was estimated that each cavity contains 59 electrons which corresponds to a solvent molecule of chloroform as suggested by chemical analysis, or half a molecule of CHCl 3 per molecule of complex.

Computing details
Data collection: CrysAlis PRO (Agilent, 2010); cell refinement: CrysAlis PRO (Agilent, 2010); data reduction: CrysAlis PRO (Agilent, 2010); program(s) used to solve structure: SIR2004 (Burla et al., 2005; program(s) used to refine structure: SHELXL97 (Sheldrick, 2008); molecular graphics: ORTEPIII (Burnett & Johnson, 1996) and ORTEP-3 (Farrugia, 1997); software used to prepare material for publication: SHELXL97 (Sheldrick, 2008).   Special details Experimental. Absorption correction: Empirical absorption correction using spherical harmonics, implemented in SCALE3 ABSPACK scaling algorithm (CrysAlisPro; Agilent, 2010). 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 cell s.u.'s are taken into account individually in the estimation of s.u.'s in distances, angles and torsion angles; correlations between s.u.'s in cell parameters are only used when they are defined by crystal symmetry. An approximate (isotropic) treatment of cell s.u.'s is used for estimating s.u.'s involving l.s. planes. Refinement. Refinement of F 2 against ALL reflections. The weighted R-factor wR and goodness of fit S are based on F 2 , conventional R-factors R are based on F, with F set to zero for negative F 2 . The threshold expression of F 2 > σ(F 2 ) is used only for calculating R-factors(gt) etc. and is not relevant to the choice of reflections for refinement. R-factors based on F 2 are statistically about twice as large as those based on F, and R-factors based on ALL data will be even larger.