Isomers of icosaborane(26): some synthetic routes and preliminary characterisations in the bis(nido-decaboranyl) system

Abstract

Bis(nido-decaboranyl), (B₁₀H₁₃)₂, is the largest neutral borane yet reported; it has 11 possible geometric isomers and four of these should exist as enantiomeric pairs, making a total of 15 distinct structures. Photolytic, thermolytic, and metathetical routes to these compounds have been developed. Five of the geometric isomers have been isolated by chromatography and examined by u.v., n.m.r., and mass spectroscopy; another three isomers have been tentatively identified. The spectroscopic data do not permit unambiguous structural assignments at present, but the two major products from the reaction of Mg(B₁₀H₁₃)I with B₁₀H₁₃(Cl-6) may be the (5,6′) and (6,6′) isomers.