Computational Design of Novel Organotin(IV) Monomers: A Theoretical Study of Hypercoordination and Solvent Effects

Candidate: Pierre Rouanet
Supervisor: Dr. Stephen Wylie

ABSTRACT

Polystannanes could find application as novel, cost-effective semiconductors for thin-film electronics, molecular wires and printable electronic circuits due to their low energy band gap (2 - 4 eV). Added electron density along the Sn-Sn backbone provided by hypercoordinate interactions between the Sn(IV) Lewis acid center and ligands containing electron donating groups (NR2, OR, PR2O, SR… where R = alkyl or aryl) helps prevent their degradation. Optimized computational methodology for studying hypercoordinate organotin(IV) monomers was determined by comparing the 119Sn NMR shift of an experimental reference to the computationally predicted shift at various levels of DFT theory and solvation modeling. The best functional, r2SCAN-3c, and solvation model, COSMO, was used to model and compare dual hypercoordinate “pincer” organotin(IV) monomers. Hypercoordination was also explored with computational techniques such as Boltzmann averaging, and natural bonding orbital (NBO) calculations. Experimental and computational 1H, 13C and 119Sn NMR were used to determine how solvents affected the existing hypercoordinate interaction.