The Transfer Hydrogenation of Cinnamaldehyde Using Homogeneous Cobalt(II) and Nickel(II) (E)-1-(Pyridin-2-yl)-N-(3-(triethoxysilyl)propyl)methanimine and the Complexes Anchored on Fe3O4 Support as Pre-Catalysts: An Experimental and In Silico Approach

Fortunate P Sejie; Olayinka A Oyetunji; James Darkwa; Isaac N Beas; Banothile C E Makhubela; Nelson Y Dzade; Nora H de Leeuw

doi:10.3390/molecules28020659

The Transfer Hydrogenation of Cinnamaldehyde Using Homogeneous Cobalt(II) and Nickel(II) (E)-1-(Pyridin-2-yl)-N-(3-(triethoxysilyl)propyl)methanimine and the Complexes Anchored on Fe₃O₄ Support as Pre-Catalysts: An Experimental and In Silico Approach

Molecules. 2023 Jan 9;28(2):659. doi: 10.3390/molecules28020659.

Authors

Fortunate P Sejie¹, Olayinka A Oyetunji¹, James Darkwa^{2

3}, Isaac N Beas², Banothile C E Makhubela³, Nelson Y Dzade^{4

5}, Nora H de Leeuw^{5

6}

Affiliations

¹ Department of Chemistry, University of Botswana, Gaborone Private Bag UB 00704, Botswana.
² Botswana Institute for Technology Research and Innovation, Gaborone Private Bag 0082, Botswana.
³ Department of Chemical Sciences, University of Johannesburg, P.O. Box 524, Auckland Park 2006, South Africa.
⁴ Department of Energy and Mineral Engineering, Pennsylvania State University, University Park, PA 16802, USA.
⁵ School of Chemistry, Cardiff University, Main Building, Park Place, Cardiff CF10 3AT, UK.
⁶ School of Chemistry, University of Leeds, Leeds LS2 9JT, UK.

Abstract

The imino pyridine Schiff base cobalt(II) and nickel(II) complexes (C1 and C2) and their functionalised γ-Fe₃O₄ counterparts (Fe₃O₄@C1 and Fe₃O₄@C2) were synthesised and characterised using IR, elemental analysis, and ESI-MS for C1 and C2, and single crystal X-ray diffraction for C1, while the functionalised materials Fe₃O₄@C1 and Fe₃O₄@C2 were characterized using IR, XRD, SEM, TEM, EDS, ICP-OES, XPS and TGA. Complexes C1, C2 and the functionalised materials Fe₃O₄@C1 and Fe₃O₄@C2 were tested as catalysts for the selective transfer hydrogenation of cinnamaldehyde and all four pre-catalysts showed excellent catalytic activity. Complexes C1 and C2 acted as homogeneous catalysts with high selectivity towards the formation of hydrocinnamaldehyde (88.7% and 92.6%, respectively) while Fe₃O₄@C1 and Fe₃O₄@C2 acted as heterogeneous catalysts with high selectivity towards cinnamyl alcohol (89.7% and 87.7%, respectively). Through in silico studies of the adsorption energies, we were able to account for the different products formed using the homogeneous and the heterogeneous catalysts which we attribute to the preferred interaction of the C=C moiety in the substrate with the Ni centre in C2 (-0.79 eV) rather than the C=O (-0.58 eV).

Keywords: Fe3O4-immobilised pre-catalysts; cinnamaldehyde; transfer hydrogenation.

Grants and funding

AQ140028/Royal Society of London, UK