Metal Atoms Collinear with the Spiro Carbon of 6,6-Open Adducts, M_2@C_(80)(Ad) (M = La and Ce, Ad = Adamantylidene)

摘要

The photochemical reaction of M_2@C_(80) (M = La and Ce) with 2-adamantane-2,3'-[3H]-diazirine (1) affords the corresponding adducts by carbene addition. The adducts were characterized by spectroscopic and single-crystal X-ray structure analyses. Crystallographic data for the adduct La_2@C_(80)(Ad) (2, Ad = adamantylidene) reveal that the two La atoms are collinear with the spiro carbon of the 6,6-open adduct. It is noteworthy that the La-La distance is highly elongated by the addition of carbene. Paramagnetic (~13)C NMR spectral analysis of the adduct Ce_2@C_(80)(Ad) (3) indicates that the two Ce atoms are also collinear with the spiro carbon at room temperature in solution. The unique metal positions were confirmed by density functional calculations.