Structures cristallines et moléculaires des muscs macrocycliques III. La muscone et sa 2,4-dinitrophénylhydrazone

Muscone (3-methylcyclopentadecanone C16H30O) forms orthorhombic plastic-crystals with Z = 2 (a = 5.560(4), b = 8.176(6), c = 17,168(20) Å). Single crystals are obtained by zone melting at 258 °K. The high degree of disorder and the ambiguity of space group have precluded a structural determination by X-ray diffraction methods. The crystal structure of muscone 2,4-dinitrophenylhydrazone (DNPHM; C22H34N4O4, triclinic, space group P¯, a = 8.015 (4), b = 8.235 (2), c = 17.409 (4) Å. α = 102.69 (4), β; = 93.86 (3), γ = 96.03 (3)° Z = 2) was solved by direct methods and refined to a final R of 0.155 (Rω = 0.102). The macrocycle shows static disorder, which could be partially resolved by analysis of the anisotropy of the atomic vibrational parameters. Eight possible conformers with reasonable geometries emerged from the subsequent refinements and were used as starting models in force-field calculations, which converged to four quinquangular conformations ([25233]; [34233]; [21423*4]; [3423*4]) with similar energies. In the molecular packing, the interactions between macrocycles and substituents are minimized. They are comparable to those described for the cis- and trans-civetone DNPH derivatives [1] [2].</p