MoO-05


CYANO ADDUCT-ANIONS OF FULLERENE-60 OBSERVED BY ELECTROSPRAY MASS SPECTROMETRY

George Khairallah and J. Barrie Peel

School of Chemistry, La Trobe University, Bundoora, Victoria 3083


Negative-ion electrospray mass spectrometry of C60 / CN- solutions was used to study the cyano adduct-anions of buckminsterfullerene, revealing three abundant monoanionic species, namely C60(CN)n-, n = 1, 3, 5, with C60(CN)- as the dominant anion, and three dianionic species C60(CN)n2-, n = 2, 4, 6 [1]. While multiply charged anions of C60, from C602- up to C606- have been observed by electrochemical reduction and in alkali metal doped solid phases, the cyano-adducts described here include the first multiply-charged negative-ions of C60 adducts to be observed.

The C60 reaction with cyanide anion recently reported by Wudl and coworkers [2], forms the mono-adduct anion, C60(CN)-, as a soluble salt, which is then the precursor for a number of syntheses of neutral C60 compounds. The C60(CN)- species is present at low CN- concentrations, but at higher concentrations the higher monoanions appear, with the dianions formed at the highest concentrations.

No C60- or triply-charged species are observed. The dianionic species are likely to have radically different structures to the neutral and monoanionic species. Calculations using the MOPAC program with the AM1 approximation suggest that negative charge separation has an important effect on geometry.

1. G. Khairallah and J.B. Peel, submitted for publication.
2. K.-K. Majid, B. Knight, G. Srdanov and F. Wudl, J. Am. Chem. Soc., 1995, 117, 11371.