π-Conjugated Heteroles Containing Group 13 Elements

This research targeted the synthesis of group 13 neutral heteroles via transmetallation of the tin atom in stannole moieties. The synthesis of Heteroles of 15a (1-chloro-2,3,4,5-tetraphenylborole), 15b (1-chloro-2,3,4,5-tetraphenylaluminole) and 15c (1-chloro-2,3,4,5-tetraphenylgallole) were attempted. The potential formation of Lewis base adducts were explored through the addition of a coordinating solvent of THF, Et3N, and Et2O and characterized with NMR (1H, 13C and 11B where applicable). It was attempted to synthesize Polymer 17a from the di-brominated borole monomer 16a via a Pd-catalyzed polycondensation reaction. THF was subsequently added to the polymer in an attempt to produce the polymer adduct 17a·THF. This was performed to produce a stable enough material for GPC analysis. The polymer was also characterized with NMR. Theoretical calculations were undertaken at the B3LYP/6-31G* level of DFT to help identify the effect of HOMO-LUMO energy gap of the above heteroles and their adducts. DFT calculations reveal that monomers and oligomer energy gaps can be tuned by substituents attached to the heterole, the type of Lewis adduct formed and the degree of catenation. These monomers and oligomers could potentially be novel building blocks for the synthesis of small energy gap π-conjugated systems.