Jump to main content
Jump to site search

Issue 25, 2013
Previous Article Next Article

Organometallic calcium and strontium borohydrides as initiators for the polymerization of ε-caprolactone and L-lactide: combined experimental and computational investigations

Author affiliations

Abstract

[Ca(BH4)2(THF)2] (1a), a known compound, was easily prepared following a convenient new procedure from [Ca(OMe)2] and BH3·THF in THF. Reaction of 1a with KCp* (Cp* = (η5-C5Me5)) and K{(Me3SiNPPh2)2CH} in a 1 : 1 ratio in THF resulted in the corresponding dimeric heteroleptic mono-borohydride derivatives [Cp*Ca(BH4)(THF)n]2 (2a) and [{(Me3SiNPPh2)2CH}Ca(BH4)(THF)2] (3a), respectively. Both compounds were fully characterized and the solid-state structure of 3a was established by single crystal X-ray diffraction. Compounds 1a, 2a, and 3a, together with the earlier reported compounds [Sr(BH4)2(THF)2] (1b), [Cp*Sr(BH4)(THF)2]2 (2b), and [{(Me3SiNPPh2)2CH}Sr(BH4)(THF)2] (3b), were used as initiators for the ROP of polar monomers. The general performances of the complexes in the ROP of ε-caprolactone and L-lactide demonstrate a relatively good control of the polymerization under the operating conditions established. α,ω-Dihydroxytelechelic poly(ε-caprolactone)s (PCLs) and poly(lactide)s (PLAs) were thus synthesized. DFT calculations on the initiation step of the ROP of ε-CL were carried out. Gibbs free energy profiles were determined for the three calcium complexes highlighting slightly more active calcium complexes as compared to strontium analogues, in agreement with experimental findings.

Graphical abstract: Organometallic calcium and strontium borohydrides as initiators for the polymerization of ε-caprolactone and l-lactide: combined experimental and computational investigations

Back to tab navigation

Supplementary files

Publication details

The article was received on 04 Jan 2013, accepted on 26 Feb 2013 and first published on 21 Mar 2013


Article type: Paper
DOI: 10.1039/C3DT00037K
Citation: Dalton Trans., 2013,42, 9352-9360
  •   Request permissions

    Organometallic calcium and strontium borohydrides as initiators for the polymerization of ε-caprolactone and L-lactide: combined experimental and computational investigations

    M. Kuzdrowska, L. Annunziata, S. Marks, M. Schmid, C. G. Jaffredo, P. W. Roesky, S. M. Guillaume and L. Maron, Dalton Trans., 2013, 42, 9352
    DOI: 10.1039/C3DT00037K

Search articles by author

Spotlight

Advertisements