The Effect of Carborane Substituents on the Lewis Acidity of Boranes

The Lewis acidity of primary, secondary,and tertiary boraneswith phenyl, pentafluorophenyl, and all three isomers of the icosahedralcarboranes (ortho, meta, and para) was investigated by computing their fluoride, hydride,and ammonia affinities as well as their global electrophilicity indicesand LUMO energies. From these calculations, it was determined thatthe substituent effects on the Lewis acidity follow the trend of ortho-carborane > meta-carborane > para-carborane > C6F5 > C6H5. TheLewis acidity of primary, secondary, and tertiaryboranes withphenyl, pentafluorophenyl, and all three isomers of the C-substitutedicosahedral carboranes (ortho, meta, and para) was investigated by computing theirfluoride, hydride, and ammonia affinities as well as their globalelectrophilicity indices and LUMO energies. From these calculations,it was determined that the substituent effects on the Lewis acidityof these boranes follow the trend of ortho-carborane> meta-carborane > para-carborane> C6F5 > C6H5.

Automated summary

The Lewis acidity of primary, secondary, and tertiary boranes with phenyl, pentafluorophenyl, and all three isomers of the icosahedral carboranes was studied by calculating their affinities for fluoride, hydride, and ammonia, as well as their electrophilicity indices and LUMO energies. It was found that the substituent effects on Lewis acidity followed the trend of ortho-carborane > meta-carborane > para-carborane > C6F5 > C6H5.