Exploration of Bis(nickelation) of 1,1′-Bis(o-carborane)

The metalation of [Tl](2)[1-(1 '-3 ',1 ',2 '-closo-TlC2B9H10)-3,1,2-closo-TlC2B9H10], with the smaller {Ni(dmpe)} fragment sourced from [Ni(dmpe)Cl-2], is explored. The bis(metalated) products are obtained as a diastereoisomeric mixture. These isomers were separated, fully characterised spectroscopically and crystallographically and identified as rac-[1-(1 '-3 '-(dmpe)-3 ',1 ',2 '-closo-NiC2B9H10)-3-(dmpe)-3,1,2-closo-NiC2B9H10] (1) and meso-[1-(1 '-3 '-(dmpe)-3 ',1 ',2 '-closo-NiC2B9H10)-3-(dmpe)-3,1,2-closo-NiC2B9H10] (2). 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)Cl-2] was also studied. These bis(nickelated) products were also fully characterised and are afforded as the stereospecific species rac-[1-(1 '-3 '-(dppe)-3 ',1 ',2 '-closo-NiC2B9H10)-3-(dppe)-3,1,2-closo-NiC2B9H10] (3) and [1-(2 '-4 '-(dppe)-4 ',1 ',2 '-closo-NiC2B9H10)-3-(dppe)-3,1,2-closo-NiC2B9H10] (4 alpha). In the latter metalation, compound 3 shows intramolecular dihydrogen bonding, contributing to the stereospecificity, whereas isomerisation from 3,1,2 to 4,1,2- in the 4 alpha is related to steric relief.

Automated summary

The metalation of a thallium salt with nickel fragments resulted in the formation of bis(nickelated) products, which were characterized and identified as different stereospecific species. The study also demonstrated the achievement of new structures by utilizing different nickel fragments in the metalation process.