Cubane structure of sodium derivatives of tetradentate Schiff bases

Abstract

Reaction of sodium hydride in thf (tetrahydrofuran) with H₂salphen [N,N′-o-phenylenebis-(salicylideneimine)] or H₂salen [N,N′-ethylenebis(salicylideneimine)] gave the corresponding sodium derivatives Na₂(salphen)(thf)_n and Na₂(salen)(thf)_n. Recrystallization from 1,2-dimethoxyethane (dme) gave the stable solvated forms [Na₄(salphen)₂(dme)₂]2 and [Na₄(salen)₂(dme)₂]2. From the X-ray analysis both have very similar structures with a cubane skeleton of alternate sodium and oxygen atoms. Crystallographic details: complex 1, space group P2₁/c, a= 12.045(1), b= 25.851(2), c= 16.467(1)Åα=γ= 90°, β= 107.61(1)°, Z= 4 and R= 0.079 for 2118 independent observed reflections; 2, space group P2₁/n, a= 20.493(2), b= 21.682(2), c= 20.538(2)Å, α= 90°, β= 110.53(1)°, Z= 8 and R= 0.071 for 5054 independent observed reflections.