Synchrotron X-ray investigation of α-Chlorohemin, C34H32ClFeN4O4, an Fe-porphyrin

• Combined synchrotron X-ray data and DFT calculations.
• Structure of α-Chlorohemin (C34H32ClFeN4O4, Fe-porphyrin) determined (100 K and 298 K).
• Reference powder diffraction patterns for α-Chlorohemin (C34H32ClFeN4O4) determined.
• Intermolecular hydrogen bonding observed in the structure.

X-ray data of a powder sample of α-chlorohemin (a member of the porphyrin family), C34H32ClFeN4O4, was collected using synchrotron radiation at the Advanced Photon Source (APS, Argonne National Laboratory). Rietveld Refinement and Density Functional Theory (DFT) calculations were performed for obtaining the structure including positions of hydrogen atoms. The structure was found to be P1¯, Z = 2; at 100K the lattice parameters are a = 11.22468(6) Å, b = 13.93930(8) Å, c = 10.79818(9) Å, α = 99.6672(6)°, β = 108.4124(8)°, γ = 106.7175(6)°, and V = 1471.713(19) Å3, and at 295K, a = 11.43217(7) Å, b = 14.06412(10) Å, c = 10.85390(9) Å, α = 98.6655(7)°, β = 108.6294(8)°, γ = 107.5025(7)°, and V = 1517.21(2) Å3, Dx = 1.427 g/cm3. Experimental reference X-ray patterns have also been determined, which will be included in the Powder Diffraction File (PDF).

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