Anisotropic Magnetic Behavior of Anionic Ce@C₈₂ Carbene Adducts

Derivatives of Ce@C82(C2v) have been synthesized and fully characterized, and their anisotropic magnetism has been observed as paramagnetic shifts in NMR measurements. Carbene addition by photochemical reaction afforded two isomers of Ce@C82(C2v)Ad (Ad = adamantylidene), 2a and 2b, demonstrating high regioselectivity. The two isomers were characterized using MALDI−TOF mass spectrometry, vis−NIR absorption spectroscopy, 1H and 13C NMR spectroscopy, and electrochemistry. The structure of the minor isomer (2b) was elucidated by single-crystal X-ray structural analysis. 13C and 1H NMR measurements revealed the characteristic anisotropic interaction between the f electron on the Ce atom and nuclear spins of the carbon atoms of the cage and the protons of the Ad group, respectively.