Tin—Tin π Bonding as a Conduit for Alkali‐Metal Reduction

Abstract Reactions of the doubly reduced distannynes, [Ar′SnSnAr′M 2 ], (Ar′ = C 6 H 3 ‐2,6‐Dipp; M = Li, Na, K), with the successively heavier group 1 elements (M′) result in reduction of M and the isolation of [Ar′SnSnAr′M′ 2 ]. Although the viability of these observations, along with the reversible formation of [Ar′SnSnAr′K 2 ] by treatment of [Ar′SnSnAr′Rb 2 ] with potassium, is successfully predicted by a combined theoretical and thermochemical analysis, assessment of the bonding within [Ar′SnSnAr′M 2 ] suggests that any M + n s valence orbital contribution should be too high in energy to effect M + reduction. Based on a consideration of the Sn─Sn π bonding and theoretical assessment of the resultant frontier orbitals, however, we suggest that the electron transfer necessary for M + reduction, occurs intramolecularly and via a suitably disposed π* SOMO of the putative radical anions, [Ar′SnSnAr′M 2 ] •− .