Jump to main content
Jump to site search

Issue 25, 2013
Previous Article Next Article

Potassium, zinc, and magnesium complexes of a bulky OOO-tridentate bis(phenolate) ligand: synthesis, structures, and studies of cyclic ester polymerisation

Author affiliations

Abstract

Reaction of the OOO-coordinating tridentate bis(phenolate) protio-ligand 2,2′-{oxybis(methylene)}bis{4,6-di(1-methyl-1-phenylethyl)phenol} (LO3-H2), with 1 equiv. of KN(SiMe3)2 in toluene or THF yielded [K(LO3-H)] (1) or [K(LO3-H)(THF)] (2), respectively. Single-crystal X-ray diffraction studies of 1 and 2 revealed mononuclear structures with the phenyl rings of the bulky ligand displaying stabilising π-interactions to the potassium centre. LO3-H2 also reacts with 1 equiv. of ZnEt2 or MgnBu2 to give [M2(LO3)2] (M = Zn (3) or Mg (4)) in good yield. The molecular structures of complex 3 and 4 reveal dinuclear species in which the metal centres are tetra-coordinated to the three oxygen atoms of one LO3 ligand, and to the bridging oxygen atom of one phenolate group of another. Complexes 1–4 are catalysts for ring-opening polymerisation of ε-caprolactone and L- and rac-lactide in the presence of benzyl alcohol (BnOH) and also other initiators to give the corresponding polyesters. Kinetic studies for the ROP of ε-caprolactone using 3 and BnOH gives an unusual rate expression Rp = −d[CL]/dt = kp[BnOH]0[3]00.5 for which a tentative kinetic model is proposed.

Graphical abstract: Potassium, zinc, and magnesium complexes of a bulky OOO-tridentate bis(phenolate) ligand: synthesis, structures, and studies of cyclic ester polymerisation

Back to tab navigation

Supplementary files

Publication details

The article was received on 14 Jan 2013, accepted on 13 Feb 2013 and first published on 14 Feb 2013


Article type: Paper
DOI: 10.1039/C3DT50135C
Citation: Dalton Trans., 2013,42, 9313-9324
  •   Request permissions

    Potassium, zinc, and magnesium complexes of a bulky OOO-tridentate bis(phenolate) ligand: synthesis, structures, and studies of cyclic ester polymerisation

    Y. Huang, W. Wang, C. Lin, M. P. Blake, L. Clark, A. D. Schwarz and P. Mountford, Dalton Trans., 2013, 42, 9313
    DOI: 10.1039/C3DT50135C

Search articles by author

Spotlight

Advertisements