Well-defined transition metal complexes with phosphorus and nitrogen ligands for 1,3-dienes polymerization

Novel Allyl Cobalt Phosphine Complexes: Synthesis, Characterization and Behavior in the Polymerization of Allene and 1,3-Dienes

“…Moreover, the H g and H Me' interaction (cross peak 3, Figure S3) seems to suggest that they are oriented on the same side, that is compatible with an exo-endo reciprocal orientation of the allylic group and of the isoprene unit ( Figure 6A); on the other hand the complete absence of any interactions between H i,e and H f,k with the aryl and methyl protons of the phosphine ligand are also in favor of an exo-endo orientation of the allylic group and of the isoprene unit. This means that when the phosphine ligand is PMePh 2 , both the arrangements (exo-exo and exo-endo) are possible, in agreement indeed with the formation of atactic 1,2 polymers in the polymerization of terminally substituted monomers such as 1,3-pentadiene and 1,3-hexadiene [18] with catalyst based on complex 3, as reported below in the text. Figure S3) seems to suggest that they are oriented on the same side, that is compatible with an exo-endo reciprocal orientation of the allylic group and of the isoprene unit ( Figure 6A); on the other hand the complete absence of any interactions between Hi,e and Hf,k with the aryl and methyl protons of the phosphine ligand are also in favor of an exo-endo orientation of the allylic group and of the isoprene unit.…”

“…The structures of these new allyl complexes, determined through NMR and X-ray techniques, and the structure of the polymers obtained, determined by NMR spectroscopy, provided further support and confirmation of the 1,3-dienes polymerization mechanism that has been proposed previously [18,22].…”

“…We reported in previous papers that, in general, the stereoselectivity in the polymerization of 1,3-dienes with transition metal complex-based catalysts [e.g., CrCl2(L)/MAO (L = bidentate phosphine); FeCl2(L)2-MAO (L = phenanthroline); CoCl2(L)2/MAO (L = monodentate phosphine)] was strongly affected by the catalyst structure (i.e., type of ligand bonded to the metal atom) and by the monomer structure [22][23][24][25][26][27][28][29][30]. The obtained results clearly indicated that (i) the exo-exo orientation of the allyl group of the growing chain and of the coordinated monomer was strongly favored in case of 1,3-butadiene and terminally substituted monomers, and of hindered ligands on the cobalt atom; (ii) the exo-endo orientation was instead favored in case of internally substituted 1,3-butadienes (e.g., isoprene and 3-methyl-1,3-pentadiene) and low hindered ligands on the metal atom [18]. Such a behavior is now confirmed, and even more evident, in case of the polymerization of 1,3-dienes with the allyl cobalt complexes object of the present paper.…”

Butadiene Polymerization Catalyzed by Tri(aryloxo)aluminum Adduct of Cobalt Acetate

“…6 Recent academic activities have focused on the construction of metal dichloride complexes coordinated by elaborate ligands, which can be activated with methylaluminoxane (MAO) or [Ph 3 C] + B(C 6 F 5 ) 4 − , to elucidate the effect of ligand structure on the polymerization reactivity. [7][8][9][10][11][12][13][14][15][16][17][18][19] However, considering the high price of MAO or [Ph 3 C] + B(C 6 F 5 ) 4 − and the cost of constructing the elaborate complexes, these catalytic systems are seldom relevant for commercial use.…”

One-Dimensional Coordination Polymers of Lanthanide Cations to Cucurbit[7]uril Built Using a Range of Tetrachloride Transition-Metal Dianion Structure Inducers

“…Similar supramolecular architectures are also called metal-organic frameworks (MOFs), as well as coordination networks, with some inconsistency in the distinctions between the terms [1][2][3][4][5][6]. Coordination polymers span scientific fields such as organic and inorganic chemistry, biology, materials science, electrochemistry and pharmacology and have many potential applications [7].…”