Encapsulation Studies on -Dicarbadodecaborane Isomers in Neutral Tetrahedral Palladium(II) Cages.

The encapsulation of icosahedral -dicarbadodecaborane (-, -, and -carboranes, ) as guest molecules at the intrinsic cavities of the three isostructural tetrahedral cages [{Pd(NPr)PO}(Cl-AN)] (), [{Pd(NPr)PO}(Br-AN)] (), and [{Pd(NPr)PO}(H-AN)] () was studied. The formation of definite host-guest assemblies was probed with mass spectrometry, IR, and NMR spectral analysis. 2D DOSY H NMR of the ⊂Cage systems showed similar diffusion coefficient () values for the host and guest species, signifying the encapsulation of these guests inside the cage assemblies. The hydrodynamic radius () derived from the values of the host and guest species further confirmed the encapsulation of the isomers at the cage pockets. The single-molecule energy optimization of the host-guest assemblies indicated the preferential binding of - as a guest inside the cages (-). The stabilization of these guests inside these cages was further attributed to various possible nonclassical C-H···X-type interactions.