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N3/4-pyridinyl Schiff base copper(II) benzoate complexes: synthesis, crystal structures and ring-opening polymerization studies

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Abstract

Five benzoate complexes of copper(II) were synthesized by the reaction of N-donor Schiff base ligands with copper(II) acetate and benzoate co-ligands. All complexes were characterized by physicochemical, spectroscopic techniques and single-crystal X-ray diffraction studies. Crystal structure analysis revealed mononuclear complexes Cu(C6H5COO)2(L1)2·H2O (1) with a square pyramidal geometry and Cu(Me-C6H5COO)2(L2)2·2H2O (3) with a distorted octahedral geometry around the Cu(II) center. Three other complexes [Cu(C6H5COO)2(L2)]2·(2), [Cu(Me-C6H5COO)2(L3)]2·(4) and [Cu(C6H5COO)2(L4)]2·(5) all adopted a paddlewheel conformation in which the two Cu(II) centers each have a square pyramidal geometry. All complexes were found to be active as catalyst in ring-opening polymerization of ɛ-caprolactone (ε-CL), yielding low molecular weight polymers of about 2200 g mol−1 to 3870 g mol−1. The activity of complex 4 increased with the addition of different alcohol co-initiators except in t-butanol where a reduction was obtained arguably due to steric hindrance.

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Acknowledgements

We thank the University of Kwa-Zulu Natal, School of Physics and Chemistry for an enabling environment for the research.

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Authors and Affiliations

  1. School of Chemistry and Physics, University of KwaZulu-Natal, Westville Campus, Private Bag X54001, Durban, 4000, South Africa

    Damilola C. Akintayo, Wisdom A. Munzeiwa & Sreekantha B. Jonnalagadda

  2. Chemistry Department, Bindura University of Science Education, Private Bag 1020, Bindura, Zimbabwe

    Wisdom A. Munzeiwa

  3. School of Chemistry and Physics, University of KwaZulu-Natal, Pietermaritzburg Campus, Private Bag X01, Scottville, 3209, South Africa

    Bernard Omondi

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  1. Damilola C. Akintayo
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DCA contributed to conceptualization, software, formal analysis, investigation methodology, data curation, and writing—original draft preparation. WAM contributed to visualization, investigation, validation, and reviewing and editing. SBJ contributed to supervision, resources, and project administration. BO contributed to conceptualization, resources, writing—reviewing and editing, supervision, and project administration.

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Akintayo, D.C., Munzeiwa, W.A., Jonnalagadda, S.B. et al. N3/4-pyridinyl Schiff base copper(II) benzoate complexes: synthesis, crystal structures and ring-opening polymerization studies. Transit Met Chem 47, 113–126 (2022). https://doi.org/10.1007/s11243-022-00494-8

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