The reaction between [3-Et-7,8-Ph2-7,8-nido-C2B9 H8]2- and Ni(dppe)Cl2 in tetrahydrofuran affords major and minor products, identified spectroscopically and crystallographically. The major species is 1,2-Ph2-4-dppe-6-Et-4,1,2-closo-NiC2B9 H8, which arises from the presumed initial product 1,2-Ph2-3-dppe-6-Et-3,1,2-closo-NiC2B9H8 by a sterically induced 1,2 ? 1,2 C atom isomerization, typical of overcrowded nickelacarboranes. The minor species is 1,8-Ph2-2-dppe-4-Et-2,1,8-closo-NiC2B9 H8, arising from an unexpected 1,2 ? 1,7 carbon-atom isomerization of the initial product. The fact that one boron atom is labelled with an Et group, coupled with the fact that these isomerizations occur at low temperatures, allows comment on the isomerization mechanisms. The minor isomer cannot be explained by reference to Wales' sequential diamond - square - diamond mechanism for 1,2-closo- C2B10H12 ? 1,7-closo-C2B10H12. A simple rationalization of the formation of both major and minor isomers is available through triangle face rotation. Copyright © 2003 John Wiley & Sons, Ltd.
|Number of pages||7|
|Journal||Applied Organometallic Chemistry|
|Publication status||Published - Jun 2003|
- Crystallographic study
- Vertex labelling