New tetrylenes based on substituted diethylenetriamines: synthesis and use as initiators for ε-caprolactone polymerization

The reactions of 3-benzyl-1,5-ditosyl-1,3,5-triazapentane (1) and 3-benzyl-1,5-dimesityl- 1,3,5-triazapentane (2) with one equivalent of Lappert´s germylene or stannylene (M[N(SiMe₃)₂]₂, where M = Ge, Sn) produced germylenes and stannylenes of the general formula PhCH₂N(CH₂CH₂NR)₂M, where M = Ge, R = 4-MeC₆H₄SO₂– (3); 2,4,6-Me₃C₆H₂– (5); M = Sn, R = 4-MeC₆H₄SO₂– (4); 2,4,6-Me₃C₆H₂– (6), in satisfactory yields. According to NMR data (¹H, ¹³C, ¹¹⁹Sn), stannylenes 4 and 6 are monomeric in solution, and the coordination number of tin is four. The synthesized stannylenes exhibited very high (compound 4) and moderate (compound 6) activity as initiators for bulk polymerization of ε-caprolactone, resulting in the synthesis of high-molecular-weight polymers with relatively narrow molecular-weight distribution. Previously unknown triamine 2 was synthesized by benzylation of HN(CH₂CH₂NHMes)₂ with benzyl chloride in the presence of K₂CO₃.