Darstellung einer molekularen,monomeren thallium(I)-Verbindung mit einem neuen chelatisierenden Liganden

The chelating ligand Me₃COSiMe₂N(CMe₃)H (III) can easily be prepared in high yields and has been employed for the synthesis of some metal derivatives. With n-butyllithium III forms Me₂Si(Me₃CO)(Me₃CNLi)]₂ (IV), which is found to be dimeric in solution and in the gas phase. When IV is allowed to react with thallium(I) chloride in diethyl ether the monomeric, highly reactive Me₂Si- (Me₃C$\text{O)(Me}{}_3\text{CNTl}$) (II) is formed under precipitation of lithium chloride. The cyclic structure and the physical properties of II can be understood on the basis of isosteric relation to cyclic diazasilastannylenes. II forms the tetramer (TlOMe)₄ with methanol and does not add methyl iodide to the metal, the thalium containing product being TII. With magnesium dichloride in diethyl ether yields thallium(I) chloride and the spiro compound Me₂Si(Me₃CO)(Me₃CN)]₂-Mg (VI), in which magnesium exhibits 4-fold coordination.