| In low-temperature isolation experiments and Fourier-transform mass spectrometry studies, carbon oxides act as precursors to the cyclocarbons C{dollar}sb{lcub}18{rcub}{dollar}, C{dollar}sb{lcub}24{rcub}{dollar}, and C{dollar}sb{lcub}30{rcub}{dollar}. The FTMS experiments also demonstrate that the cyclocarbon cations can coalesce to form fullerenes size-selectively, with particularly efficient yields of C{dollar}sb{lcub}60{rcub}sp+{dollar} and C{dollar}sb{lcub}70{rcub}sp+{dollar}. These results imply that resistance to addition of mid-sized rings or to loss of C{dollar}sb2{dollar} may explain the preferential formation of C{dollar}sb{lcub}60{rcub}{dollar} and C{dollar}sb{lcub}70{rcub}{dollar} in bulk fullerene production. Further FTMS experiments probed other potential precursors to small all-carbon molecules, including phosphorus-stabilized ketenylidene oligomers and diiodopolyynes. In addition, efforts toward the synthesis of 1,20-diphenyl-1,3,5,7,9,11,13,15,17,19-eicosadecayne led to a new method for preparation of 1-(triisopropylsilyl)-1,3,5-hexatriyne and 1-(triisopropylsilyl)-6-(trimethylsilyl)-1,3,5-hexatriyne. |
