Lithium, magnesium, zinc complexes supported by tridentate pincer type pyrrolyl ligands: Synthesis, crystal structures and catalytic activities for the cyclotrimerization of isocyanates. (8th January 2015)

• Record Type: Journal Article
• Authors: Liu, Qiao; Guo, Zhiqiang; Han, Hongfei; Tong, Hongbo; Wei, Xuehong
• Is Part Of: Polyhedron. Volume 85(2015)
• Page Start: 15
• Page End: 19
• Publication Date: 2015-01-08
• Subjects: Pyrrolyl -- Tridentate -- Synthesis -- Cyclotrimerization -- Isocyanate; Chemistry, Inorganic -- Periodicals; Chimie inorganique -- Périodiques; Organometaalverbindingen; Anorganische chemie; 546.05
• DOI: 10.1016/j.poly.2014.08.009
• Languages: English
• ISSNs: 0277-5387

Abstract

Graphical abstract: A convenient and practical method for the cyclotrimerization of isocyanates is described. The reaction was catalyzed in the presence of catalytic amounts (1.0 mol%) of lithium, magnesium, zinc complexes incorporating substituted symmetrical tridentate pyrrolyl ligands leads to the corresponding isocyanurates in good yields. The best result was obtained when the lithium compound was employed as initiator. Abstract: Lithium, magnesium, zinc complexes incorporating substituted symmetrical tridentate pyrrolyl ligands were synthesized conveniently and their application for the cyclotrimerization of isocyanate to corresponding isocyanurate has been investigated. The reaction of 1 equivalent of 2, 5-bis(pyrrolidinomethyl)pyrrole {C4 H2 NH(2, 5-CH2 NC4 H8 )2 } with n-BuLi generated [Li{C4 H2 N(2, 5-CH2 NC4 H8 )2 }]2 (1 ) in diethyl ether. Treatment of 2 equivalents of C4 H2 NH(2, 5-CH2 NC4 H8 )2 with MgBu2 or ZnEt2 in THF afforded [Mg(THF){C4 H2 N(2, 5-CH2 NC4 H8 )2 }2 ] (2 ) or [Zn{C4 H2 N(2, 5-CH2 NC4 H8 )2 }2 ] (3 ) in high yield, respectively. Compounds1, 2 and3 were characterized by 1 H and 13 C NMR spectra and their molecular structures were determined by single crystal X-ray diffraction. Furthermore, compounds1, 2 and3 were proved to be moderate to good initiators for cyclotrimerization of isocyanate to the corresponding isocyanurate in diethyl ether.