高周期典型元素多重結合化合物の化学の新展開 : 『重いケトン』を求めて

抄録

Recent studies on the synthesis, structure, and reactivity of kinetically stabilized double-bond compounds between group 14 metals (M=Si, Ge, and Sn) and heavier chalcogens such as sulfur or selenium are reviewed. Three different approaches for the formation of “heavy ketones” were examined, i. e., (i) the thermal retrocycloaddition of 1, 2, 4, 3-trichalcogenametallolanes bearing a new steric protection group, 2, 4, 6-tris- [bis (trimethylsilyl) methyl] phenyl (denoted as Tb), (ii) the reactions of kinetically stabilized divalent group 14 metal species, Tb (Ar) M, with an epichalcogenide or elemental chalcogen, and (iii) the dechalcogenation reactions of 1, 2, 3, 4, 5-tetrachalcogenametallolanes, Tb (Ar) MY₄ (Y=, S, Se). As a result of kinetic stabilization by the combination of Tb and 2, 4, 6- triisopropylphenyl (Tip) group, silanethione Tb (Tip) Si S and germanethione Tb (Tip) Ge=S were successfully isolated as monomeric and stable crystalline compounds, while the corresponding stannanethione Tb (Tip) Sn = S was synthesized as a monomeric species stable in solution, Of particular note is the X-ray crystallographic structure analysis of germanethione, which revealed the completely trigonal planar geometry for the germathiocarbonyl unit and the remarkable bond shortening for the Ge-S double bond.