NOVEL TRICARBONYLCHROMIUM COMPLEXES OF 1,10 AND 1,8-DIHYDRO-1,6-METHANO[10]ANNULENES AND THEIR RICOCHET INTERRING HAPTOTROPIC REARRANGEMENTS

butyl-1,8-dihydro-1,6-methano[10]annutene)chromium (10) and some other complexes of similar structure were prepared by treatment of (1,2,3,4 ,5,6-eta)-1,6-methano[10]annulene)chromium with n-BuLi. 10 was charact erized by a single-crystal X-ray diffraction study and H-1 and C-13 NM R spectra. Crystal data for 10: C18H20O3Cr, P1BAR, a = 7.811(3) angstr om, b = 10.191(4) angstrom, c = 10.996(4) angstrom, alpha = 80.96(3)-d egrees, beta = 80.68(3)-degrees, gamma = 75.15(3)-degrees, Z = 2, V = 828.7(7) angstrom3. Reversible intramolecular inter-ring haptotropic r earrangements were observed for the derivatives of 10 under thermal co nditions. The migration of a Cr(CO)3 group between the eta6-2-7 and et a6-5-10 positions in the ligand is accompanied by sigmatropic shifts o f hydrogen endo atoms. The rearrangement mechanism is discussed.