Investigation of Bimetallic Nickel Catalysts in Catalyst‐Transfer Polymerization of π‐Conjugated Polymers

Abstract

A comparative study involving bimetallic nickel catalysts designed from disubstituted N,N,N′,N′‐tetra(diphenylphosphanylmethyl)benzene diamine bridging ligands is reported. Catalyst behavior is explored in the Kumada catalyst‐transfer polymerization (KCTP) using poly(3‐hexylthiophene) (P3HT) as the model system. The success of a controlled polymerization is monitored by analyzing monomer conversion, degree of polymerization, end‐group identity, and molecular weight distribution. The characterization of P3HT obtained from KCTP initiated with the bimetallic catalysts shows chain‐growth behavior; however, the presence of Br/Br end‐groups and broader molecular weight distribution reveals a reduced controlled polymerization compared to the commonly employed Ni(dppp)Cl2. The observed increase in intermolecular chain transfer and termination processes in KCTP initiation with the bimetallic catalysts can be attributed to a weaker Ni(0)‐π‐aryl complex interaction, which is caused by increased steric crowding of the coordination sphere.

Phospha-Mannich reactions of RPH2, R2PH, and R3P

“…Entry R R' Yield, % δ P , ppm 58, [241] 67, [4] 79, [242] 92, [210] 95, [51] 97 [243] -27.2 (CDCl 3 ), -27.7 (CDCl 3 ) 71 [243] -72, [244] 76 [242] -27.1 (CDCl 3 ) 90, [242] (-)* [245] -27.5 (CDCl 3 ), -27.9 (CDCl 3 ) 74 [242] -27.6 (CDCl 3 ) 93 [243] -65, [246,247] 77 [242] -26.8 (CDCl 3 ), -27.0 (CDCl 3 /MeOH) 85 [210] -25.8 (CDCl 3 )…”

“…Entry Ar Spacer Yield, % d P , ppm 91, [309] 93, [4] 95, [139] 99, [310] (-)* [272] -27.9 (CDCl 3 ), -28.1 (CH 2 Cl 2 ), -28.2 (CDCl 3 ), -28.4 (CDCl 3 ) 99 [311] -28.5 (CDCl 3 ) 75 [312] -24.6 and -24.8 (CDCl 3 ) 75, [241] 78, [313] 81 [314] -26.6, -26.7, or -27.1 (CDCl 3 )…”

“…68, [241] 82 [315] -26.6 or -26.9 (CDCl 3 ) 81 [316] -27.6 (CDCl 3 ) 86 [314] -26.1 (CDCl 3 ) 85 [314] -27.6 (CDCl 3 ) 92 [179] -26.5 (C 6 D 6 ) 65, [223] 84 [317] -23.4 (CD 2 Cl 2 ), -24.6 (CDCl 3 ) 74 [318] -44.1 (CD 2 Cl 2 ) 71 [318] -44.0 (CD 2 Cl 2 ) * Yield is not reported Table S51. Cyclo-P,NH-acetals derived from 2-phosphinoethanamines and 3-phosphinopropan-1amines.…”

A Chain‐Growth Mechanism for Conjugated Polymer Synthesis Facilitated by Dinuclear Complexes with Redox‐Active Ligands

“…[32] Luscombe and co-workers explored Kumada CTP with dinickel catalysts, wherein the nickel centers were not directly linked, and observed uncontrolled chain growth. [34] Lastly, Uyeda and co-workers utilized a dinickel complex templated by a naphthyridine diimine ligand (NDI-Ni 2 ) to form aromatic polydiazenes by step-growth de-nitrogenative coupling of bis-azide monomers. [27,33] The latter example was, likewise, characterized by a lack of control and did not offer access to generic conjugated polymer scaffolds free of diazenes.…”

“…In 2019, Schoenebeck and co‐workers disclosed a dinuclear Pd +1 catalyst that is able to polymerize a variety of electron‐rich monomers via Negishi cross‐coupling, albeit in a manner that is neither controlled nor living [32] . Luscombe and co‐workers explored Kumada CTP with dinickel catalysts, wherein the nickel centers were not directly linked, and observed uncontrolled chain growth [34] . Lastly, Uyeda and co‐workers utilized a dinickel complex templated by a naphthyridine diimine ligand (NDI‐Ni 2 ) to form aromatic polydiazenes by step‐growth de‐nitrogenative coupling of bis‐azide monomers [27, 33] .…”