Nucleophilic substitution of a labile model tosylated triphenylstannane 4 to either aryloxy, alkyoxy or thioacetate bearing stannanes in good yields was demonstrated. DFT optimization of individual molecules using the PBE0-GD3BJ method generally provided the best predictions of solid-state molecular properties. Modelling of hypercoordinate conformations for the methoxy-series 12, 14, 18, and 22 with PBE0-GD3BJ showed that inclusion of the PCM solvent model predicts significantly shorter Sn-O distances than in the gas phase. Relativistic DFT calculations of 119 Sn chemical shifts for these conformations with Boltzmann averaging closely approximated experimental values when gas phase geometries and conformer distributions were used but performed poorly with solvent phase ones. The selection of the PBE0-GD3BJ method by "structural benchmarking" gas-phase geometries to solid-state structures may have effectively factored in the impact of a condensed phase on the hypercoordinate interactions, causing the solvation model to overestimate these. A new light and moisture stable semicrystalline polystannane, 25, was prepared by the dehydropolymerization in the presence of Wilkinson's catalyst. Evidence for extensive hypercoordination was detected by 119 Sn NMR spectroscopy. Access to the similar, but only partially substituted methoxy stannane, 28, via an SN2 reaction involving a tosylated polymeric intermediate 24 in good yields has also been demonstrated using mild reaction conditions. Despite the sensitivity of the Sn-Sn bonds of the liable polystannane, prolonged reaction periods (> 1 week) of tosyl containing polystannane 24 with a nucleophile in the absence of light can allow access to functionally stable new polystannanes.