The Central Atom Size Effect on the Structure of Group 14 Tetratolyls

The tetraphenyl derivatives of the Group 14 elements are of great potential interest as supramolecular constructs in extended porous networks. The tetratolyl Group 14 compounds were synthesized by using a general reaction scheme involving the nucleophilic addition of an organometallic reagent to the electrophilic center of the Group 14 element. The tetrachloride derivatives were used for the synthesis of the silane, germane and stannane compounds. Sn(Tol)4 was found to have tunnel splittings much smaller than the minimum line width available on IN16, whereas the lighter analogues displayed a remarkable size effect of the central atom. The tunneling peaks were observed to persist up to around 30 K, before softening and extending into the limit of quasielastic diffusion in which the rotors undergo thermally excited rotation.