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Homopiperazine and Piperazine Complexes of Zr IV and Hf IV and Their Application to the Ring‐Opening Polymerisation of Lactide
Author(s) -
Hancock Stuart L.,
Mahon Mary F.,
KociokKőhn Gabriele,
Jones Matthew D.
Publication year - 2011
Publication title -
european journal of inorganic chemistry
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.667
H-Index - 136
eISSN - 1099-0682
pISSN - 1434-1948
DOI - 10.1002/ejic.201100589
Subject(s) - chemistry , piperazine , polymerization , ligand (biochemistry) , ring (chemistry) , solid state , metal , crystallography , stereochemistry , polymer chemistry , organic chemistry , polymer , biochemistry , receptor
In this paper we describe the preparation and characterisation, by single‐crystal X‐ray diffraction, of twelve Zr IV /Hf IV complexes based on piperazine or homopiperazine salan ligands. With the piperazine ligands, a mixture of species was observed and various solid‐state structures were isolated. However, with homopiperazine salan ligands, 1:1 ligand‐to‐metal complexes were observed both in solution and in the solid state. Interestingly, for the homopiperazine complexes the isopropoxide ligands are trans to one another in the solid state, most likely because of the rigid nature of the homopiperazine backbone. All homopiperazine Hf IV and Zr IV complexes were tested for the ring‐opening polymerisation (ROP) of rac ‐lactide. The complexes are active and produce polylactide with narrow polydispersity indices. The kinetics and living characteristics of the polymerisation have also been investigated.