Tridentate pyrrolylzinc compounds: Synthesis, structures, reactivities and catalytic cyclotrimerization reaction of isocyanate
作者:Zhiqiang Guo、Xuehong Wei、Hongbo Tong、Diansheng Liu
DOI:10.1016/j.jorganchem.2014.11.009
日期:2015.1
The reactions of ZnEt2 with NNN-tridentate pincer type pyrrolyl ligands, 2,5-bis((dimethylamino) methylene)- 1H-pyrrole (HL1), 2,5-bis((pyrrolidin-1-yl)methylene)-1H-pyrrole (HL2) and 2,5-bis((piperidino) methylene)-1H-pyrrole (HL3), afford zinc ethyl compounds [C4H2N(2,5-CH2NMe2)(2)]ZnC2H5 (1), [C4H2N(2,5-CH2N(CH2)(4))(2)]ZnC2H5 (2), and [C4H2N(2,5-CH2N(CH2)(5))(2)]ZnC2H5 (3) in highyield. Subjecting 1, 2, 3 with one equivalent of tert-butylphenol in THF generated [C4H2N(2,5-CH2NMe2)(2)]Zn(O-C6H4-4-Bu-t)}(2) (4), [C4H2N(2,5-CH2N(CH2)(4))(2)]Zn(O-C6H4-4-Bu-t)}(2) (5), [C4H2N(2,5-CH2N(CH2)(5))(2)]Zn(O-C6H4-4-Bu-t)}(2) (6), respectively. Each has been characterized by satisfactory C, H and N microanalysis, NMR spectroscopy at ambient temperature, and single crystal X-ray structural analysis. The compounds Et(6)Z-n(6)O(2)[C4H2N(2,5-CH2N(CH2)(4))(2)](2) (7) and Et6Zn6O2[C4H2N(2,5-CH2N(CH2)(5))(2)](2) (8) obtained accidentally from zinc ethyl compounds with traces of water. Each of compound 1-6 has been used as initiator for cyclotrimerization of isocyanate, and the organozinc compound 3 shows moderate reactivity toward the cyclotrimerization of isocyanate in Et2O solvent under mild conditions. (C) 2014 Elsevier B.V. All rights reserved.