Synthesis of phosphine-containing dipyrromethene cobalt complexes, promising ligands for homogeneous catalysis in nanomembrane reactors

Abstract

Complexes of 5-(4-diphenylphosphinophenyl)dipyrromethene with trivalent cobalt (Ph₂PC₆H₄DP)₃Co (DP for dipyrromethene) were obtained for the first time, and their reaction with dicarbonylrhodium(I) acetylacetonate was investigated. The formed complex [Ph₂P(Rh)C₆H₄DP]₃Co was characterized by ¹H, ¹³С, and ³¹P NMR spectroscopy. The dimensions of the ligand were estimated (by geometry optimization with PM3 method) and of the formed rhodium complex (by 2D diffusion NMR spectroscopy DOSY). The size of the complex makes it possible to detain it on membranes with the pore size of 2 nm providing an opportunity to use it in catalytic processes with subsequent separation of the catalyst and the reaction products in the nanofiltration mode. Test of 1-octene hydroformylation with the use of this catalytic system showed results similar to those with the system Rh–PPh₃ both with respect to conversion in aldehydes and to the ratio of n/iso-products. Thus the fundamental possibility was demonstrated of applying the synthesized complexes in catalysis.