Triply bonded stannaacetylene (RC≡SnR): theoretical designs and characterization

The effect of substitution on the potential energy surfaces of RC≡SnR (R = F, H, OH, CH(3), SiH(3), Tbt, Ar*, SiMe(SitBu(3))(2), and SiiPrDis(2)) was explored using density functional theories (B3LYP/LANL2DZdp and B3PW91/Def2-QZVP). Our theoretical investigations indicate that all the triply bonded RC≡SnR molecules prefer to adopt a trans-bent geometry, which is in good agreement with the theoretical model (mode B). In addition, we demonstrate that the stabilities of the RC≡SnR compounds bearing smaller substituents (R = F, H, OH, CH(3), and SiH(3)) decrease in the order R(2)C═Sn: > RC≡SnR > :C═SnR(2). On the other hand, the triply bonded R'C≡SnR' molecules with bulkier substituents (R' = Tbt, Ar*, SiMe(SitBu(3))(2), and SiiPrDis(2)) were found to possess the global minimum on the singlet potential energy surface and are both kinetically and thermodynamically stable. Further, we used the B3LYP computations to predict the stability of stannaacetylene bearing the very bulky phosphine ligand. Our theoretical observations strongly suggest that both the electronic and the steric effects of bulky substituents play an important role in making triply bonded stannaacetylene (RC≡SnR) an intriguing synthetic target.