Syntheses and Crystal Structures of Simple Dibenzylcalcium Complexes: Useful Reagents in the Preparation of Calcium Compounds

Abstract

Synthetic routes to dibenzylcalcium or para-substituted dibenzylcalcium complexes are described. Crystal structures of trans-(p-tBu-benzyl)2Ca·(THF)4 and cis-(benzyl)2Ca·(THF)4 show similar Ca−C and Ca−O bond distances. The observation of different geometries (cis/trans) is explained by packing effects (DFT methods calculate less than 2 kcal/mol energy difference between cis- and trans-geometries). The strongly basic dibenzylcalcium complexes are useful precursors in calcium chemistry. Triphenylmethane was deprotonated, and the highly symmetric structure of [Ph3C-]2[Ca2+·(THF)6] is discussed.