Exploration of Bis(nickelation) of 1,1′-Bis(<i>o</i>-carborane)

• Published in: Crystals
• Main Authors: Dipendu Mandal, Georgina M. Rosair
• Format: Article
• Language: English
• Published: MDPI AG 2020-12-01
• Subjects: 1,1′-bis(<i>o</i>-carborane); deboronation; metalation; bis(nickelation); diastereoisomers; stereospecific
• Online Access: https://www.mdpi.com/2073-4352/11/1/16

The metalation of [Tl]₂[1-(1′-3′,1′,2′-<i>closo</i>-TlC₂B₉H₁₀)-3,1,2-<i>closo</i>-TlC₂B₉H₁₀], with the smaller {Ni(dmpe)} fragment sourced from [Ni(dmpe)Cl₂], is explored. The bis(metalated) products are obtained as a diastereoisomeric mixture. These isomers were separated, fully characterised spectroscopically and crystallographically and identified as <i>rac</i>-[1-(1′-3′-(dmpe)-3′,1′,2′-<i>closo</i>-NiC₂B₉H₁₀)-3-(dmpe)-3,1,2-<i>closo</i>-NiC₂B₉H₁₀] (<b>1</b>) and <i>meso</i>-[1-(1′-3′-(dmpe)-3′,1′,2′-<i>closo</i>-NiC₂B₉H₁₀)-3-(dmpe)-3,1,2-<i>closo</i>-NiC₂B₉H₁₀] (<b>2</b>). Previously, these 3,1,2-NiC₂B₉-3′,1′,2′-NiC₂B₉ architectures (where both cages are not isomerised), were inaccessible, and thus new structures can be achieved during bis(nickelation) with {Ni(dmpe)}. Further, the metalation of the tetra-thallium salt with the bulky {Ni(dppe)} fragment sourced from [Ni(dppe)Cl₂] was also studied. These bis(nickelated) products were also fully characterised and are afforded as the stereospecific species <i>rac</i>-[1-(1′-3′-(dppe)-3′,1′,2′-<i>closo</i>-NiC₂B₉H₁₀)-3-(dppe)-3,1,2-<i>closo</i>-NiC₂B₉H₁₀] (<b>3</b>) and [1-(2′-4′-(dppe)-4′,1′,2′-<i>closo</i>-NiC₂B₉H₁₀)-3-(dppe)-3,1,2-<i>closo</i>-NiC₂B₉H₁₀] (<b>4</b>α). In the latter metalation, compound <b>3</b> shows intramolecular dihydrogen bonding, contributing to the stereospecificity, whereas isomerisation from 3,1,2 to 4,1,2- in the <b>4</b>α is related to steric relief.