Fullerometallic Ion Chemistry: Reactions of C 60 Fe + and C 20 H 10 Fe + in the Gas Phase Doina Caraiman, ² Gregory K. Koyanagi, ² Lawrence T. Scott, ‡ Dorin V. Preda, ‡ and Diethard K. Bohme* ,² Contribution from the Department of Chemistry, Centre for Research in Mass Spectrometry, and Centre for Research in Earth and Space Science, York UniVersity, Toronto, Ontario M3J 1P3, Canada, and Department of Chemistry, Merkert Chemistry Center, Boston College, Chestnut Hill, Massachusetts 02467-3860 ReceiVed February 22, 2001 Abstract: Fe + has been attached to buckminsterfullerene, C 60 , and corannulene, C 20 H 10 , in the gas phase, and the reactivities of C 60 Fe + and C 20 H 10 Fe + have been measured with several small inorganic and organic molecules in helium bath gas at 0.35 Torr using a selected-ion flow tube (SIFT) mass spectrometer. Comparisons with measured reactivities of the bare Fe + ion indicate that the presence of C 60 and C 20 H 10 leads to enhancements in reactivity at room temperature of up to 5 orders of magnitude. Ligation was the only chemistry observed with D 2 ,N 2 , CO 2 , CH 4 ,C 2 H 2 ,C 2 H 4 , SO 2 ,C 6 D 6 , NH 3 ,H 2 O, and CO, but other channels were observed to compete with adduct formation in the reactions with N 2 O and O 2 . The number of molecules sequentially ligated to the ion was different: up to five molecules of ligand added sequentially to Fe + , up to four molecules of ligand were observed to attach to C 60 Fe + , while only up to three molecules added to C 20 H 10 Fe + .C 60 + and C 20 H 10 + were observed to be unreactive toward the same ligands. The kinetic results show the influence of carbonaceous surfaces on metal ion reactivity and are interpreted in terms of the nature of the coordination of Fe + to the carbonaceous surface. Catalytic effects of the carbonaceous surfaces were identified for the reactions with N 2 O and O 2 . Introduction The study of fullerometallic chemistry began with the pioneering work of Smalley and co-workers, who observed the formation of the endohedral La@C 60 species in laser vaporiza- tion studies. 1 Since then, several research groups have explored exohedral and endohedral metallofullerenes and their ionic counterparts in the gas phase, 2a,d in the condensed phase 3a,e and from a theoretical point of view. 4a,c Huang and Freiser generated exohedral C 60 M + species (M ) Fe, Co, Ni, Cu, Rh, La, V) in an ICR-FTMS mass spectrometer via a multistep sequence initiated by laser desorption to generate M + from pure metal targets followed by the reaction of the metal ion with C 60 . 5 For metal ions that reacted with C 60 predominantly by electron transfer, a procedure involving ligand exchange was used in order to enhance the C 60 M + intensity over that observed by direct attachment. Low-energy collision-induced dissociation (CID) experiments with C 60 M + in Ar buffer gas (at about 2 × 10 -6 Torr) indicated formation of either M + or C 60 + depending on IE(M) and a weak interaction between the exohedral metal ion and the carbon surface (D(C 60 -Fe + ) ) 44 ( 7 kcal mol -1 ). 6 Exohedral C 60 M + species (M ) Fe, Mn, Cr, Mo, W) have also been obtained in a guided ion beam mass spectrometer from the direct reaction of metal ions generated by electron- bombardment ionization of metal carbonyls and C 60 vapor. 7 Two distinct types of C 60 Fe + complexes were observed to be formed over a collision energy range from 1 to 100 eV. At low collision energies, a weakly bound (coordination) complex was formed with no activation barrier that dissociates by loss of Fe. A second type of C 60 Fe + complex was observed at collision energies above 10 eV. 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