title: The first silastannene >si=sn<: a new doubly-bonded system of heavier group 14 elements.
abstract: The reaction of bis[di-tert-butyl(methyl)silyl]dilithiosilane 1 with dichlorobis(2,4,6-triisopropylphenyl)stannane in THF at room temperature yielded highly air- and moisture-sensitive deep violet crystals of 1,1-bis[di-tert-butyl(methyl)silyl]-2,2-bis(2,4,6-triisopropylphenyl)-1-sila-2-stannaethene 2 with a Si=Sn double bond. The molecular structure of 2 was established by X-ray crystallography, which showed a trans-bent structure (bending angles of 26.2 degrees for the sp2 Si atom and 9.6 degrees for the sp2 Sn atom) with a >Si=Sn< bond length of 2.4188(14) A and a twisting angle of 34.6 degrees . The geometry and regioselectivity of the addition reaction of PhEH (E = O and S) corresponds to the polarity of the double bond Sidelta-=Sndelta+, which is also supported by theoretical calculations on the model silastannene (H3Si)2Si=SnPh2.
authors.affiliation: Department of Chemistry, University of Tsukuba, Tsukuba, Ibaraki 305-8571, Japan. sekiguch@staff.chem.tsukuba.ac.jp
authors.forename: Akira
authors.initials: A
authors.lastname: Sekiguchi
authors.forename: Rika
authors.initials: R
authors.lastname: Izumi
authors.forename: Vladimir Ya
authors.initials: VY
authors.lastname: Lee
authors.forename: Masaaki
authors.initials: M
authors.lastname: Ichinohe