Divalent tin and lead complexes of a bulky salen ligand: the syntheses andstructures of [Salen(But),Me]Sn and [Salen(But),Me]Pb

The divalent tin and lead complexes, [Salen(But,Me)]Sn and [Salen(But,Me)]P b, have been synthesized by the reactions of [(Me3Si)(2)N](2)M (M = Sn, Pb) with the substituted Salen compound, [Salen(But,Me)]H-2. [Salen(But,Me)]Sn and [Salen(But,Me)]Pb have been characterized by X-ray diffraction, which demonstrates that the complexes are structurally similar, with the metal at om located above the [N2O2] plane. Despite their similar structures, howeve r, H-1 NMR spectroscopy demonstrates that the barrier for the formal transf er of the metal from one face of the ligand to the other is significantly g reater for the tin derivative.