Synthesis and Propylene Oxide Carbonylation Hydroesterification Catalytic Property of N,O-Ligand Coordination Cobalt Compounds

Nine N,O-ligands L-1 similar to L-9 have been synthesized. L-1 similar to L-4 each reacted with half equivalent Co-2(CO)(8) by redox coordination to produce neutral mononuclear cobalt compounds 1 similar to 4. Reactions of L-5 similar to L-9 each with equivalent Co-2(CO)(8) occurred by disproportionation and redox coordination to afford 5 similar to 7. When the reaction of L-8, 5/6 equiv. of Co-2(CO)(8), 1.2 equiv. of MeOH, and 0.4 equiv. of H2O took place via disproportionation and redox coordination to give compound 8, L-9 and 0.5 equiv. of Co-2(CO)(8) happened through disproportionation coordination to form compound 9. Compounds 5 similar to 9 are all the ionic species with the same anion [Co(CO)4](-), but coupled by mononuclear cobalt cation for 5 similar to 7 and 9 whereas trinuclear cation for 8. Compounds 1 similar to 9 have been characterized by FT-IR spectroscopies and elemental analysis, of which 1 and 8 were further determined by X-ray crystallography. The catalytic property of propylene oxide (PO) carbonylation hydroesterification using 1 similar to 9 was investigated, achieving PO conversions of 42.6%similar to 99.0% and beta-hydroxy methylbutyrate (HMB) yields of 34.1%similar to 88.6%. The time-traced reactions were carried out for both catalysts 8 and 9, and the catalytic reaction mechanism based on cooperative interplay by the homonuclear cobalt ion pair was discussed as well.