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Constrained geometry scandium permethylindenyl complexes for the ring-opening polymerisation of l- and rac-lactide

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Abstract

The synthesis and characterisation of constrained geometry scandium permethylindenyl chloride, aryloxide and borohydride complexes Me2SB(tBuN,I*)Sc(Cl)(THF) (1), Me2SB(tBuN,I*)Sc(O-2,6-iPr-C6H3)(THF) (2), Me2SB(tBuN,I*)Sc(O-2,4-tBu-C6H3)(THF) (3) and Me2SB(tBuN,I*)Sc(BH4)(THF) (4) are reported. The activity of complexes 1–4 as initiators for the ring-opening polymerisation (ROP) of L- and rac-lactide is presented. The ROP of L- and rac-lactide using complexes 2 and 3 show first-order dependence on monomer concentration, and produced isotactic polylactide (PLA) and moderately heterotactic PLA (Pr = 0.68–0.72), respectively. Good agreement between experimental and theoretical molecular weights of PLA (Mn) and relatively narrow dispersities (Mw/Mn < 1.20) were obtained. Complex 4 showed higher activity for ROP of L- and rac-lactide than 2 or 3, with second-order dependence on monomer concentrations. However, poorly controlled molecular weights and lower heteroselectivity (Pr = 0.61–0.67) were observed. The effect of temperature and catalyst concentration for the ROP of L-lactide using 2 and 3 was also studied.

Graphical abstract: Constrained geometry scandium permethylindenyl complexes for the ring-opening polymerisation of l- and rac-lactide

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Publication details

The article was received on 25 Aug 2019, accepted on 08 Oct 2019 and first published on 09 Oct 2019


Article type: Paper
DOI: 10.1039/C9DT03450A
Dalton Trans., 2019, Advance Article

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    Constrained geometry scandium permethylindenyl complexes for the ring-opening polymerisation of L- and rac-lactide

    N. Diteepeng, J. Buffet, Z. R. Turner and D. O'Hare, Dalton Trans., 2019, Advance Article , DOI: 10.1039/C9DT03450A

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