Moleküle mit ungewöhnlich langen N(sp2)–Si(sp3)-Bindungen: Synthese und Kristallstrukturen von 1,2-Benzoldisulfonylaminosilanen

Polysulfonylamines. XCIV. Molecules with Unusually Long N(sp²)–Si(sp³) Bonds: Synthesis and Crystal Structures of 1,2-Benzenedisulfonylaminosilanes The following compounds were obtained by metathesis of silver 1,2-benzenedisulfonimide (AgZ) with the appropriate chlorosilanes: ZSiMe₃ ( 4 ), ZSiⁿPr₃, ZSiMe₂ⁿBu, ZSiMe₂(CMe₂–CHMe₂) ( 7 ), (Z)₂SiMe₂ ( 8 ). In the crystal structures of 4 (monoclinic, space group P2₁/n), 7 (monoclinic, P2₁/c) and 8 (monoclinic, P2₁/n), which were determined by low-temperature X-ray diffraction, the molecules adopt the N-silyl form and display unusually long bonds between the trigonal-planar N and the tetrahedrally coordinated Si atoms ( 4 : 182.6, 7 : 184.1, 8 : 177.8 and 180.5 pm). For 7 in CDCl₃ solution, ¹H and ¹³C NMR data indicate N,O-silylotropy. The solid state structures of molecules 4 and 7 strongly suggest that the N–Si bond lengthening in N,N-disulfonylated aminosilanes is mainly induced by the π-acceptor character of the SO₂ groups and not by the occasionally observed coordination expansion of the Si atom through short intramolecular O…Si contacts.