1613407-84-3Relevant academic research and scientific papers
Ring-opening polymerization of cyclic esters by pincer complexes derived from alkaline earth metals
Lamberti, Marina,Botta, Antonella,Mazzeo, Mina
, p. 140 - 145 (2014)
We report the synthesis and characterization of new Ca(II) and Mg(II) complexes of the type [Ph - PPP]MR (M = Ca, R = N(SiMe3)2 (1); M = Mg, R = nBu (2)) where Ph - PPP- is a tridentate monoanionic ligand (Ph - PPP - H = bis(2-diphenylphosphinophenyl)phosphine). Reaction of the opportune metal precursor (Ca[N(SiMe3) 2]2.THF2 or MgnBu2) with 1 equiv. of the pro-ligand Ph - PPP-H produces the corresponding calcium amido (1) or magnesium butyl (2) complex in high yield. Solution NMR studies show monomeric and kinetically stable structures for both species. The obtained complexes efficiently mediate the ring-opening polymerization of E-caprolactone showing a turnover frequency of 40 000 h-1. In the presence of a hexogen alcohol, up to 2000 equiv. of monomer are converted by using a low loading of catalyst (5 μmol). Kinetic studies show a first-order reaction in monomer concentration. Copyright
