Low-Coordinate Tin and Lead Cations

A series of low-coordinate tin and lead cationic complexes have been synthesized using the bulky ß-diketiminate ligand [{N(2,6- iPr2C6H3)C(Me)}2CH] - (BDI) to stabilize the metal center. Two different routes to [(BDI)Sn]+[X]- and [(BDI)Pb]+[X]- were explored (X = B(C6F5)4, AlCl4, MeB(C6F5)3): abstraction of the chloride with a Lewis acid from (BDI)SnCl and (BDI)PbCl and abstraction of a methyl group with a borane from (BDI)SnMe and (BDI)PbMe. The crystal structures of the tin and lead cations were determined; in both, solvent molecules were found to coordinate to the metal center. In the case of [(BDI)Pb]+[B(C 6F5)4]-, a dichloromethane molecule was found. Density functional theory (DFT) calculations showed that this could be due to crystal packing. In the case of [(BDI)Sn]+[MeB(C 6F5)3]-, an ether molecule was coordinated to the tin metal center. DFT calculations revealed a significant energy gain for the coordinated ether as opposed to the free molecules.