A new synthetic route to boron-10 enriched pentaborane(9) from boric acid and its conversion to anti-(10)B(18)H(22).
Boron-10 enriched boric acid, H310BO3, was converted to the corresponding sodium borohydride, Na10BH4, in essentially quantitative yields, by using slightly modified literature methods involving the formation of butyl borate, (n-OBu)310B, first and then reacting it with NaH in mineral oil. The oxidation reaction of Na10BH4 with I2 in diglyme and subsequent addition/purification in dioxane gave Na[10B3H8]0.3(C4H8O2) that reacted further with NiCl2 in either anhydrous benzene or heavy mineral oil at 110 degrees C to produce the corresponding 10B5H9 as the first isolated 10B-enriched liquid boron hydride in a laboratory environment. Treatment of this 10B5H9 with NaH or t-BuLi in 2:1 molar ratio underwent a cage expansion reaction to produce the [M]10B9H14 that undergoes a redox reaction in situ with anhydrous NiCl2 in n-hexane to yield the corresponding fused cage anti-10B18H22 as the only solid borane product in 42% yield, thus establishing new synthetic routes for the preparation of 10B-enriched polyhedral boranes.
Adams
Luqman
L
Department of Chemistry and Biochemistry, Northern Illinois University, DeKalb, Illinois 60115-2862, USA.
Hosmane
Sumathy N
SN
Eklund
Jamey E
JE
Wang
Jianhui
J
Hosmane
Narayan S
NS