Crystal structure of chlorido{5,10,15,20-tetrakis[2-(2,2-dimethylpropanamido)phenyl]porphyrinato-κ4 N}iron(III)

The title compound, [Fe(C64H64N8O4)Cl], is a five-coordinate square-pyramidal porphyrin complex with a chloride ion in the axial position, being coordinated from the protected side of the porphyrin; the FeIII atom is displaced by 0.474 (5) Å from the 24-atom mean plane of the porphyrin core towards the chloride. The porphyrin moiety is a ‘picket-fence’ 5,10,15,20-tetrakis[2-(2,2-dimethylpropanamido)phenyl]porphyrinate (por) group. The Fe—Cl bond length is 2.221 (2) Å and the Fe—N(por) bond lengths are in the range 2.043 (5)–2.063 (5) Å. The supramolecular architecture of the crystal is sustained by C—H⋯O interactions between the pyrrolic and phenyl H atoms of one molecule and the carbonyl O atoms of the 2,2-dimethylpropanamido groups of adjacent molecules. The methyl groups of three of the four tert-butyl substituents exhibited rotational disorder over two positions. The investigated crystal was twinned by a twofold rotation about the (001) axis with a refined twin ratio of 0.4086 (16).


Related literature
For the synthesis of (T piv PP)FeCl (piv = ortho-pivalamido), see: Collman et al. (1975). For the crystal structures of other neutral and anionic (T piv PP)FeCl complexes, see: Dhifet et al.   Table 1 Hydrogen-bond geometry (Å , ). derivatives in our laboratory (Cheng et al., 2000) and those of several research groups (Nasri et al., 1997;Bominaar et al., 1992;Gismelseed et al., 1990). The molecular structure of the title compound is shown in Fig. 1. The complex (T piv PP)FeCl is square pyramidal and has the chloride atom bonded to iron at the axial position. The chloride ion is coordinated at the protecting 2,2-dimethylpropanamido side of the porphyrin, in contrast to a similar structure reported (Dhifet et al., 2011) where the chloride ligand was on the opposite side of the protecting group. The Fe-Cl bond length is 2.221 (2) Å and the Fe-N(por) bond lengths are in the 2.043 (5)-2.063 (5) Å range. The iron(III) atom is displaced by 0.474 (5) Å from the 24-atom mean plane of the porphyrin core. An Fe-Cl bond length of 2.301 (2) Å and a mean Fe-N(por) distance of 2.108 (±0.015) Å were observed in the related anionic [(T piv PP)FeCl]compound (Schappacher et al. 1983). Similarly, Dhifet and coworkers (Dhifet et al., 2011) determined an Fe-N(por) distance of 2.065 (2) Å, an Fe-Cl distance of 2.207 (2) and an iron displacement of 0.420 (4) Å from the 24 atom mean plane of the porphyrin macrocycle.

S2. Experimental
The (T piv PP)FeCl complex with the chloride ion coordinated to iron at the protected side of the porphyrin was obtained serendipitously as follows: To a Schlenk tube equipped with a magnetic stirrer was added (T piv PP)FeCl (Collman et al., 1975) (50 mg, 0.045 mmol) and toluene (10 mL). p-Fluorophenylmagnesium bromide in THF (0.05 mL, 0.05 mmol) was then added drop-wise and the mixture stirred under N 2 in the dark for 24 h. The resulting red solution was filtered into a clean Schlenk tube and the toluene solution reduced to ca 3 mL under vacuum. Hexane (10 mL) was added to the solution and placed in a -20 °C freezer overnight. The solid obtained was collected by filtration and dried in vacuo to give a black microcrystalline product. The IR (KBr) spectrum of the product shows a strong ν CO band at 1694 cm -1 . X-ray quality crystals were obtained from slow evaporation of dichloromethane/ hexane solution of the complex at room temperature under N 2 . We are unsure if the title complex with the chloride in the protected porphyrin cavity was present as a component of our bulk starting reagent (T piv PP)FeCl.

S3. Refinement
H atoms were located geometrically and refined using a riding model on their parent atoms, with C-H = 0.95 Å for aromatic and 0.98 Å for aliphatic, with U iso (H) = 1.2-1.5U eq (C). The selected crystal was twinned by a 2-fold rotation about the (0 0 1) axis with a refined twin ratio of 0.4086 (16). The methyl groups of three of the t-butyl substituents were disordered: the occupancies of atoms C29 -C31 were refined to 0.759 (13) and 0.241 (13) for the unprimed and primed atoms; the occupancies of atoms C40 -C42 refined to 0.894 (9) and 0.106 (9) for the unprimed and primed atoms; and the occupancies for atoms C62 -C64 refined to 0.807 (9) and 0.192 (9) for the unprimed and primed atoms. The 1-2 and supporting information sup-2 . E71, m42-m43 1-3 distances of the carbons of the disordered methyl groups were set to approximately equal. The displacement parameters of the disordered carbons were restrained to be approximately equal along bonds. Two reflections, i.e. (-4 1 1) and (-5 6 4), were omitted from the final refinement owing to poor agreement. A single large (1.25 e Å 3 ) peak was observed in the difference map about half way between the Fe and Cl

Figure 1
The molecular structure of the title compound (I), showing the atom-labelling scheme and displacement ellipsoids drawn at the 50% probability level. Disordered groups and H atoms have been omitted for clarity.

Figure 2
The packing arrangement of molecules of the title compound (I).