Novel Tricarbonylchromium Complexes of 1,10- and 1,8-Dihydro-1,6-methano[10]annulenes and Their Ricochet Inter-Ring Haptotropic Rearrangements
摘要:
Tricarbonyl((2,3,4,5,6,7-eta)-l-n-butyl-1,8-dihydro-1,6-methano[10]annutene)chromium (10) and some other complexes of similar structure were prepared by treatment of tricarbonyl((1,2,3,4,5,6-eta)-1,6-methano[10]annulene)chromium with n-BuLi. 10 was characterized by a single-crystal X-ray diffraction study and H-1 and C-13 NMR spectra. Crystal data for 10: C18H20O3Cr, P1BAR, a = 7.811(3) angstrom, b = 10.191(4) angstrom, c = 10.996(4) angstrom, alpha = 80.96(3)-degrees, beta = 80.68(3)-degrees, gamma = 75.15(3)-degrees, Z = 2, V = 828.7(7) angstrom3. Reversible intramolecular inter-ring haptotropic rearrangements were observed for the derivatives of 10 under thermal conditions. The migration of a Cr(CO)3 group between the eta6-2-7 and eta6-5-10 positions in the ligand is accompanied by sigmatropic shifts of hydrogen endo atoms. The rearrangement mechanism is discussed.