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. Isocyanates and carbon dioxide capture between the tetrel-pnictogen bonds of functionalized [P 7 ] cages is investigated by NMR and IR spectroscopy, signal crystal X-ray diffraction, and density functional theory.