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

Yassin Belghith; Jean-Claude Daran; Habib Nasri

doi:10.1107/S1600536812032564

. 2012 Jul 25;68(Pt 8):m1104–m1105. doi: 10.1107/S1600536812032564

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

Yassin Belghith ^a, Jean-Claude Daran ^b, Habib Nasri ^a,^*

PMCID: PMC3414153 PMID: 22904760

Abstract

In the title complex, [CoCl(C₄₄H₂₈N₄)(C₅H₅N)]·0.5CHCl₃ or [Co^III(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—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—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.

Related literature

For general background on cobalt porphyrin species and their applications, see: Sanders et al. (2000 ▶). For the synthesis of Co(II) tetraphenylporphyrin, see: Madure & Scheidt (1976 ▶). For metalloporphyrins used as biomimetic models for haemoproteines, see: Dhifet et al. (2010 ▶); Mansour et al. (2010 ▶). For the structures of related compounds, see: Ali et al. (2011 ▶); Goodwin et al. (2001 ▶); Hodgson et al. (2002 ▶); Iimuna et al. (1988 ▶); Jentzen et al. (1997 ▶); Konarev et al. (2003 ▶); Mikolaiski et al. (1989 ▶); Sakurai et al. (1976 ▶); Shirazi & Goff (1982 ▶); Toronto et al. (1998 ▶). For the Cambridge Structural Database, see: Allen (2002 ▶). For details of the SQUEEZE routine in PLATON, see: Spek (2009 ▶).

Experimental

Crystal data

[CoCl(C₄₄H₂₈N₄)(C₅H₅N)]·0.5CHCl₃
M _r = 845.90
Monoclinic,
a = 13.0467 (3) Å
b = 23.4240 (7) Å
c = 14.3264 (5) Å
β = 103.541 (3)°
V = 4256.5 (2) Å³
Z = 4
Mo Kα radiation
μ = 0.60 mm⁻¹
T = 180 K
0.45 × 0.37 × 0.36 mm

Data collection

Oxford Xcalibur Sapphire2 diffractometer with a large Be window
Absorption correction: multi-scan (CrysAlis PRO; Agilent, 2010 ▶) T _min = 0.802, T _max = 0.804
43618 measured reflections
8690 independent reflections
7213 reflections with I > 2σ(I)
R _int = 0.035

Refinement

R[F ² > 2σ(F ²)] = 0.039
wR(F ²) = 0.108
S = 1.07
8690 reflections
505 parameters
H-atom parameters constrained
Δρ_max = 0.30 e Å⁻³
Δρ_min = −0.37 e Å⁻³

Data collection: CrysAlis PRO (Agilent, 2010 ▶); cell refinement: CrysAlis PRO; data reduction: CrysAlis PRO; 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.

Supplementary Material

Crystal structure: contains datablock(s) I, global. DOI: 10.1107/S1600536812032564/su2453sup1.cif

e-68-m1104-sup1.cif^{(28.3KB, cif)}

Structure factors: contains datablock(s) I. DOI: 10.1107/S1600536812032564/su2453Isup2.hkl

e-68-m1104-Isup2.hkl^{(501.7KB, hkl)}

Additional supplementary materials: crystallographic information; 3D view; checkCIF report

Table 1. Hydrogen-bond geometry (Å, °).

Cg2, Cg3, Cg6, Cg9, Cg11 and Cg12 are the centroids of the N2/C6–C9, N3/C11–C14, Co/N1/C4–C6/N2, N5/C45–C49, C27–C32 and C33–C38 rings, respectively.

D—H⋯A	D—H	H⋯A	D⋯A	D—H⋯A
C24—H24⋯Cg3ⁱ	0.95	2.79	3.543 (3)	137
C28—H28⋯Cg9ⁱⁱ	0.95	2.79	3.735 (3)	172
C35—H35⋯Cg2ⁱⁱⁱ	0.95	2.87	3.736 (2)	152
C38—H38⋯Cg11^iv	0.95	2.98	3.861 (3)	156
C42—H42⋯Cg12^v	0.95	2.75	3.574 (3)	146
C49—H49⋯Cg6	0.95	2.35	2.931 (3)	119

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Symmetry codes: (i) Inline graphic ; (ii) ; (iii) ; (iv) ; (v) .

Acknowledgments

The authors gratefully acknowledge financial support from the Ministry of Higher Education and Scientific Research of Tunisia.

supplementary crystallographic information

Comment

As part of a systematic investigation of metalloporphyrins used as biomimetic models for hemoproteines, several iron and cobalt porphyrin complexes has been characterized by our group (Dhifet et al., 2010; Mansour et al., 2010). Cobalt porphyrin species and their applications have been discussed by (Sanders et al., 2000). The chlorido cobalt(III) porphyrin derivative [Co^III(TPP)Cl] (TPP is the dianion of the tetraphenylporphyrin) has been known for many decades (Sakurai et al., 1976) but to the best of our knowledge no crystal structure of a mono or dichlorido Co(III) metalloporphyrin is reported to date. This is also the case for mono-pyridine or bis-pyridine Co(III) porphyrins. A search of Cambridge Structural Database (CSD, version 5.31; Allen, 2002) reveals: (i) only two mixed-axial ligands Cl–Co(III)–X (X = H₂O or EtOH) porphyrin structures; (CSD refcodes GAMTAP; Iimuna et al., 1988 and PUCNUW; Toronto et al., 1998, respectively), (ii) three mixed-axial ligands py–Co(III)–L (L is a monodentate ligand) porphyrin derivatives: the [Co^III(TpivPP)Br(py)] (refcode LANTIE; Hodgson et al., 2002), the [Co^III(TPP)(NO₂)(py)] (refcode YEQMIQ; Goodwin et al., 2001) and the [Co^III(TPP)(py)(C₃H₅O₂)] (refcode KEBMIN; Mikolaiski et al., 1989).

Concerning the ¹H NMR of cobalt metalloporphyrins, it has been noticed that the paramagnetic starting material [Co^II(TPP)] species (with the ground state configuration 3d⁷) presents down-field chemical shifts of the H_β-pyrrole protons [H_β_-pyrr = 15.75 p.p.m.]. For the diamagnetic cobalt(III) porphyrin derivatives (with the ground state configuration 3d⁶), the β-pyrrole protons resonate in the normal regions of the free base TPP porphyrin [8.1 p.p.m. < δ(H_β_-pyrr) < 9.4 p.p.m.] (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). The axial Co—Cl bond length [2.2339 (6) Å] is similar to those in the two related species: [Co^III(TPP)Cl(H₂O)] [Co—Cl = 2.216 (1) Å] and [Co^III(TMCP)Cl(OHCH₂CH₃)] (TMCP is the αβαβ-tetra-methylchiroporphyrin) [Co—Cl = 2.211 (2) Å] complexes. The Co—N_p distance [1.989 (2) Å] is slightly shorter than those of the three related derivatives [Co^III(Porph)(L)(py)] where L = Br, C₃H₅O₂ and NO₂ [2.00 (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)(NO₂)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 core with a major ruffling and saddling distortions of 52% and 39%, respectively.

The crystal packing is stabilized by weak C—H······π interactions (Table 1 and Fig. 2).

Experimental

[Co^II(TPP)] (100 mg, 0.149 mmol) (Madure & Scheidt 1976) and (150 mg, 1.441 mmol) of NaHSO₃ 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(CHCl₃). This means that the NaHSO₃ reagent did not react with [Co^II(TPP)] and that the Cl^- anion 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.