Unusual molecular structures of some sterically hindered lithium amides: electron diffraction results on gaseous [Li{N(SiMe3)2}]2 and X-ray data on crystalline monomeric Li(NHAr)(tmeda)(Ar = C6H2But3-2,4,6; tmeda = Me2NCH2CH2NMe2)

Abstract

Gaseous bis(trimethylsilyl)amidolithium at ca. 403 K is a cyclic [graphic omitted] dimer of D₂ symmetry, with Li–N 1.99(3)Å and ∠NLiN 100(3)° assuming the bridging (SiMe₃)₂ ligands to be orthogonal to the LiNLiN plane; crystalline 2,4,6-tri-t-butylanilido(N,N,N′,N′-tetramethylethylethylenediamine)lithium is a monomer at ambient temperature with lithium in a trigonal planer environment, Li–NHAr 1.895(8), average Li–NMe₂ 2.15(1)Å, ∠LiNC_Ar 155.6(4)°, and a rather short Li ⋯ H(N) distance of 2.08(4)Å.