Synthesis and Characterization of Co(II) Substituted Keggin‐Type Polyoxometalates as Novel Catalysts for the Hydroformylation of 1‐Hexene in a Thermomorphic Solvent System
Jan‐Christian Raabe, Lea Hombach, Maximilian J. Poller, Alberto Collauto, Maxie M. Roessler, Andreas J. Vorholt, Anna Katharina Beine, Jakob Albert
Abstract
Abstract Polyoxometalates (POMs) are a unique class of metal oxides, being of huge interest for the catalysis society. Co II ‐substituted phosphomolybdate POMs (namely H 7 [PCoMo 11 O 40 ], H 11 [PCo 2 Mo 10 O 40 ] and H 15 [PCo 3 Mo 9 O 40 ]) have been successfully synthesized for the first time. The structure of the new Co II substituted POMs was solved by single‐crystal X‐ray diffraction as well as vibrational (FT‐IR and Raman) and nuclear magnetic/electron paramagnetic resonance (NMR and EPR) spectroscopy and found to be of the Keggin‐type. The Co‐POMs were then applied as molecular catalysts for the hydroformylation of 1‐hexene in a thermomorphic solvent mixture of water and 1‐butanol. This is the very first example of a 1 st row transition metal POM acting as a hydroformylation catalyst achieving 46 % heptanal yield. The best results were obtained using H 11 [PCo 2 Mo 10 O 40 ] as a catalyst at 140 °C, 150 bar CO/H 2 1 : 2, and a reaction time of 4 h, paving the way for new POM‐based catalysts in hydroformylation reactions.