THE STRUCTURES OF ALKYL DERIVATIVES OF ARACHNO-1-CB4H10 FROM REACTIONS OF B4H10 WITH ALKYNES

New insight into the cleavage of a CC triple bond by the reactive borane intermediate {B4H8} under very mild conditions (70 °C) is provided by the structure of 1, the smallest known arachno‐carborane. Comparison of experimental data with the results of ab initio/IGLO/NMR studies prove that 1 is the product isolated in low yields from the gas‐phase reaction of B4H10 with MeCCH. Reactions with EtCCH and MeCCMe gave analogues of 1, but the parent compound 2,5‐μ‐CH2‐1‐CB4H8 was not accessible. (Figure Presented.) Copyright © 1994 by VCH Verlagsgesellschaft mbH, Germany