Crystal and molecular structure of a natural vanadyl porphyrin

The crystal and molecular structure of a vanadyl deoxophylloerythroetioporphyrin (dpep) extracted from oil shale has been determined by single crystal X-ray diffraction. The compound crystallizes in space group P21/c of the monoclinic system with four formula units in a cell of dimensions a 12.912(3), b 14.151(4), c 18.404(8) A, β 70.34(2)o. Block matrix least-squares refinement gives a final R index of 0.077 for 2296 reflections. The planar molecules are packed almost parallel, with the chloroform solvent molecules lying between the planes and weakly associated with the vanadyl oxygen. The molecular structure establishes the presence of an isocyclic five-membered ring, which suggests that the molecule is a derivative of chlorophyll.