Reactivity of tetrel functionalized heptapnictogen clusters towards heteroallenes.

Despite being known for decades, the solution-state molecular chemistry of heptapnictogen ([Pn ₇ ] ^3- ; Pn = P, As) clusters is not well established. Here we study heavy element derivatives of tetrel functionalized heptapnictogen clusters towards heteroallene capture, specifically isocyanates, an isothiocyanate and CO ₂ are probed. Clusters (Me ₃ Ge) ₃ P ₇ (1), (Et ₃ Ge) ₃ P ₇ (2), ( ⁿ Bu ₃ Sn) ₃ P ₇ (3), and (Me ₃ Si) ₃ As ₇ (4) were all found to capture isocyanates between all three of their tetrel-pnictogen bonds. In the case of phenyl isocyanate insertion, tetrel coordination at the isocyanate nitrogen atoms is preferred, while in the case of p -toluenesulfonyl isocyanate insertion, tetrel coordination at oxygen is preferred. Furthermore, the reaction of (Me ₃ Si) ₃ P ₇ with CO ₂ gave NMR spectra consistent with the capture of the greenhouse gas. Heteroallene insertion at these clusters was also studied using density functional theory.