Square-planar mesitylenido(triphenylphosphane)nickel(II) complexes containing bidendate N,O-ligands: Changes in catalytic efficiency upon small alterations in the ligand backbone

Influence of the Steric Demand of Coligands on the Catalytic Activity of Nickel(II) Complexes in the Copolymerization of Ethene and Carbon Monoxide

“…In this work we presented an investigation on new nickel complexes as catalysts for the copolymerization of ethene and carbon monoxide starting from the complex [Ni(L)MesPPh 3 ] K2 which is an active catalyst for the synthesis of polyketones [17,19]. In the new complexes we altered the triphenylphosphane ligand to either more or less basic P-ligands and Pligands with a higher or lower steric demand, K3, K4, K5, K6, and K7.…”

“…While the efficiency of [Ni(L)MesPPh 3 ] K2 varies between 8,000 and 10,000 g polyketone per g nickel [19],…”

“…Phosphanes are ubiquitous ligands in transition metal catalysts. By far the most popular phosphane for large scale processes is triphenylphosphane [3] which is also contained in nickel catalysts (as depicted in Figure 1) for the synthesis of polyketones via ethene/carbon monoxide copolymerization [15][16][17][18][19].…”

“…e production of aliphatic polyketones on an industrial scale is based on palladium, and palladium catalysts are also R=H F 1: Active nickel catalysts for the copolymerization reaction of ethene and carbon monoxide [15][16][17][18][19].…”

“…In terms of efficiency the nickel complexes K1 and K2 shown in Figure 1 with a bidentate N,O-chelate ligand L are the best ones to date. To investigate the in�uence of the different substituents on the N,O-chelate ligand we varied the groups of the N,O-chelate ligand as well as the ring size of the heterocycle [19,27]. As deactivation studies showed that the triphenylphosphane ligand does not dissociate during the catalytic polymerization [18] but dissociates during the decomposition process [28], we decided to investigate the in�uence of the P-ligand on the catalytic activity.…”