Syntheses and Structures of Solvent-Free bis (Trimethylsilyl)methyl Complexes of the Heavy Alkaline-Earth Metals

Abstract

Abstract Ether-free alkylmetal reagents are important precursors in organometallic chemistry. With few exceptions, there are hardly any heavier, ether-free group 2 alkylmetal complexes. Herein we describe facile synthetic methods for the synthesis of solvent-free Ae[CH(SiMe3)2]2 complexes (Ae = Ca, Sr, Ba) and discuss their structural and spectroscopic features. All complexes can be synthesized by salt metathesis procedures. Reaction of two equivalents of KCH(SiMe3)2 with one equivalent of AeI2 in Et2O and subsequent removal of all solvents under high vacuum gave ether-free Ae[CH(SiMe3)2]2 in yields of 78% (Ca), 56% (Sr) and 80% (Ba).The Ca and Sr reagents could also be obtained by a solvent-free solid state synthetic route, i.e. by ball-milling KCH(SiMe3)2 and AeI2 in a 2:1 ratio and subsequent extraction by benzene. Facile access to highly reactive, ether-free heavier Ae metal alkyl precursors is important for further development of the rapidly growing field of group 2 organometallic chemistry.