L. M. Trefonas

Crystal and molecular structure of the 2,4,7-trinitrofluorenone-hexamethylbenzene charge-transfer complex

The crystal and molecular structure of the charge-transfer complex formed between 2,4,7-trinitrofluorenone and hexamethylbenzene has been determined by single-crystal X-ray diffraction techniques. The complex crystallizes with four charge-transfer pairs in a monoclinic cell (P21/c) of dimensionsa = 9.533(1),b = 14.944(2),c= 17.470(2) Å and β = 113.18(1) °. The structure was solved by direct methods. The orderly packing of donor and acceptor molecules in parallel crystalline planes made the determination a severe test of direct methods techniques. The 2294 statistically significant reflections were refined to a final value ofR = 0.063. Estimated standard deviations were 0.004 Å in bond distances and 0.5 ° in bond angles among the non-hydrogen atoms. The acceptor and donor molecules lie in alternate (212) planes with a separation of 3.25 Å between the planes.

THE CRYSTAL AND MOLECULAR STRUCTURE OF p-NITROPHENACETURIC ACID

Abstract The crystal and molecular structure of p-NO2C6H5CH2CONHCH2COOH or C10 H11 N2O5 has been determined by single crystal x-ray diffraction techniques. The compound crystallizes in the space-group P21. /c with four molecules in a unit cell of dimensions: a = 11.8748(5)A, b = 11.2732(4)A, c = 8.8073(5)A and β = 112.966(4)°. The structure was solved by direct methods and refined to a final value of R = 0.042. The molecule assumes a conformation similar to that found for the analogous side-chain in the penicillin G molecule and hence should be a convenient model system in studying copper catalyzed degradations of penicillin. The hydrogen bonding between the amide oxygen of one molecule to the carboxylic acid proton, 2.67(1)A, and the amide nitrogen, 2.91(1)A, of another molecule creates a three-dimensional network identical to that found for hippuric acid.