The reaction of C, cluster addition to fullerene C-60 was studied using time-of-flight (TOF) mass spectrometer with laser desorption (LD). Detailed investigations of metastable peaks in C-60-C-62 mass region resulted in conclusion that primary adducts with formal C-62 composition, in contradiction to the existed conception, are unstable and decompose back to C-60 via C-2 losing. These adducts are most likely to have unclosed 'ball-with-fork' structures. as revealed by quantum-chemical investigations of reaction of G insertion into fullerene C-60 by PM3 method, and into model semi-sphere C32H12 at B3LYP/6-31G* level. (C) 2002 Published by Elsevier Science B.V.