Cubane Structure of Sodium Derivatives of Tetradentate Schiff Bases

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) Å α = 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.