Cyclische Diazastannylene, II1 Intermolekulare Lewis-Säure-Base-Addukte bei 1.3.2.4λ2 -Diazasilastannetidinen / Cyclic Diazastannylenes, II1 Intermolecular Lewis-Acid-Base Adducts of 1, 3,2,4λ 2 -Diazasilastannetidines

Abstract

1,3-Diorganyl-2,2-dimethyl-I,3,2,4λ²-diazasilastannetidines can be prepared as monomers (organyl = tert-butyl) or dimers (organyl = isopropyl) in nonpolar solvents, depending on the organic nitrogen substituent. The formation of the dimer, which is due to an intermolecular Lewis-acid-base interaction of Sn(II) with nitrogen, can be initiated by solidification. When the tertf-butyl compound is cooled below 0 °C two crystalline modifications are found: a monoclinic phase (C 2/c; a= 10.655(5); b = 24.75(1); c = 17.334(9) Å; β = 106.9(1)°) and a triclinic phase (P1̄; a = 10.68(1); b = 13.51(1); c = 12.36(1) Å; α = 96.2(1); β = 102.6(1); γ = 118.4(1)°). The crystal structures turn out to be built of dimeric and monomeric units in the first case and presumably only dimeric species in the second case. The isopropyl derivative crystallizes in the space group P 2₁/b (a = 10.77(1); b= 12.14(2); c = 11.15(2) Å; β = 120.2(2)°) with only dimeric units being present, as in the liquid. Interrelationships between the three structures are discussed.