Rare-Earth Metal Complexes Supported by Polydentate Phenoxy-Type Ligand Platforms: C-H Activation Reactivity and CO2/Epoxide Copolymerization Catalysis.

Mono- and dinuclear group 3 metal complexes incorporating polydentate bis(imino)phenoxy {N2O}- and bis(amido)phenoxy {N2O}3- ligands were synthesized by alkane elimination reactions from the tris(alkyl) M(CH2SiMe3)3(THF)2 and M(CH2C6H4-o-NMe2)3 (M = Sc, Y) precursors. Complex 1a-Y was used for the selective C-H activation of 2-phenylpyridine at the 2'-phenyl position affording the corresponding bis(aryl) product 3a-Y, which was found to be reacted reluctantly with weak electrophiles (styrene, imines, hydrosilanes). The mechanism of formation of 3a-Y was established by DFT calculations, which also corroborated high stability of the complex toward insertion of styrene, apparently stemming from the inability to form the corresponding adduct. Copolymerization of cyclohexene oxide and CO2 promoted by 1a-Y (0.1-0.5 mol %) was demonstrated to proceed under mild conditions (toluene, 70 °C, PCO2 = 12 bar) giving polycarbonates with high efficiency (maximal TON of 460) and selectivity (97-99% of carbonate units).

[1]  Charlotte K. Williams,et al.  Understanding metal synergy in heterodinuclear catalysts for the copolymerization of CO2 and epoxides , 2020, Nature Chemistry.

[2]  Ye Liu,et al.  Fast Ring‐Opening Polymerization of 1,2‐Disubstituted Epoxides Initiated by a Co III ‐Salen Complex , 2019 .

[3]  D. Lyubov,et al.  Rare-earth metal complexes as catalysts for ring-opening polymerization of cyclic esters , 2019, Coordination Chemistry Reviews.

[4]  P. Gao,et al.  Synthesis of Homo- and Heteronuclear Rare-Earth Metal Complexes Stabilized by Ethanolamine-Bridged Bis(phenolato) Ligands and Their Application in Catalyzing Reactions of CO2 and Epoxides. , 2019, Inorganic chemistry.

[5]  Bo-geng Li,et al.  Highly active tridentate amino-phenol zinc complexes for the catalytic ring-opening polymerization of ε-caprolactone , 2019, Journal of Organometallic Chemistry.

[6]  C. Kozak,et al.  Copolymerization of carbon dioxide and epoxides by metal coordination complexes , 2018, Coordination Chemistry Reviews.

[7]  Charlotte K. Williams,et al.  Indium Catalysts for Low-Pressure CO2/Epoxide Ring-Opening Copolymerization: Evidence for a Mononuclear Mechanism? , 2018, Journal of the American Chemical Society.

[8]  K. Mashima,et al.  Direct ortho-C-H Aminoalkylation of 2-Substituted Pyridine Derivatives Catalyzed by Yttrium Complexes with N,N'-Diarylethylenediamido Ligands. , 2018, Journal of the American Chemical Society.

[9]  H. Frey,et al.  Functional Polycarbonates from Carbon Dioxide and Tailored Epoxide Monomers: Degradable Materials and Their Application Potential , 2018 .

[10]  J. Okuda,et al.  Lanthanide Complexes Supported by a Trizinc Crown Ether as Catalysts for Alternating Copolymerization of Epoxide and CO2 : Telomerization Controlled by Carboxylate Anions. , 2018, Angewandte Chemie.

[11]  U. Kragl,et al.  Isospecific Copolymerization of Cyclohexene Oxide and Carbon Dioxide Catalyzed by Dialkylmagnesium Compounds , 2018 .

[12]  D. Lyubov,et al.  A quarter-century long story of bis(alkyl) rare-earth (III) complexes , 2017 .

[13]  B. Ko,et al.  Copolymerization of carbon dioxide with cyclohexene oxide catalyzed by bimetallic dysprosium complexes containing hydrazine‐functionalized Schiff‐base derivatives , 2017 .

[14]  S. Howdle,et al.  Effect of supercritical CO2 on the copolymerization behavior of cyclohexene oxide/CO2 and copolymer properties with DMC/salen-Co(III) catalyst system , 2016 .

[15]  N. Hadjichristidis,et al.  Lithium-Assisted Copolymerization of CO2/Cyclohexene Oxide: A Novel and Straightforward Route to Polycarbonates and Related Block Copolymers , 2016 .

[16]  D. Chakraborty,et al.  Group 4 complexes bearing bis(salphen) ligands: Synthesis, characterization, and polymerization studies , 2016 .

[17]  D. Darensbourg,et al.  Mechanistic Insights into Water-Mediated Tandem Catalysis of Metal-Coordination CO2/Epoxide Copolymerization and Organocatalytic Ring-Opening Polymerization: One-Pot, Two Steps, and Three Catalysis Cycles for Triblock Copolymers Synthesis , 2016 .

[18]  Arjan W. Kleij,et al.  Copolymerization of CO2 and Cyclohexene Oxide Mediated by Yb(salen)-Based Complexes , 2015 .

[19]  Y. Shibata,et al.  Aminomethylation reaction of ortho-pyridyl C-H bonds catalyzed by group 3 metal triamido complexes. , 2015, Journal of the American Chemical Society.

[20]  L. Haspeslagh,et al.  Are Solvent and Dispersion Effects Crucial in Olefin Polymerization DFT Calculations? Some Insights from Propylene Coordination and Insertion Reactions with Group 3 and 4 Metallocenes , 2015 .

[21]  P. Arnold,et al.  C-H bond activation by f-block complexes. , 2015, Angewandte Chemie.

[22]  Jianquan Hong,et al.  Versatile Reactivity of β-Diketiminato-Supported Yttrium Dialkyl Complex toward Aromatic N-Heterocycles , 2014 .

[23]  Paolo P. Pescarmona,et al.  Green polycarbonates prepared by the copolymerization of CO2 with epoxides , 2014 .

[24]  T. Roisnel,et al.  Neutral and Cationic Alkyl and Amido Group 3 Metal Complexes of Amidine-Amidopyridinate Ligands: Synthesis, Structure, and Polymerization Catalytic Activity , 2014 .

[25]  Baoli Wang,et al.  Yttrium-catalyzed addition of benzylic C-H bonds of alkyl pyridines to olefins. , 2013, Angewandte Chemie.

[26]  Sophie M. Guillaume.  Recent advances in ring-opening polymerization strategies toward α,ω-hydroxy telechelic polyesters and resulting copolymers , 2013 .

[27]  Z. Hou,et al.  Regioselective C-H alkylation of anisoles with olefins catalyzed by cationic half-sandwich rare earth alkyl complexes. , 2012, Angewandte Chemie.

[28]  Charlotte K. Williams,et al.  Efficient magnesium catalysts for the copolymerization of epoxides and CO2; using water to synthesize polycarbonate polyols. , 2012, Journal of the American Chemical Society.

[29]  H. Kaneko,et al.  End-functionalized polymerization of 2-vinylpyridine through initial C-H bond activation of N-heteroaromatics and internal alkynes by yttrium ene-diamido complexes. , 2011, Journal of the American Chemical Society.

[30]  Z. Hou,et al.  Rare-earth-catalyzed C-H bond addition of pyridines to olefins. , 2011, Journal of the American Chemical Society.

[31]  S. Klaus,et al.  Recent advances in CO2/epoxide copolymerization—New strategies and cooperative mechanisms , 2011 .

[32]  W. Goddard,et al.  An unusual hydrogen migration/C-H activation reaction with group 3 metals. , 2011, Journal of the American Chemical Society.

[33]  Wenliang Huang,et al.  Group 3 metal complexes of radical-anionic 2,2'-bipyridyl ligands. , 2010, Inorganic chemistry.

[34]  Wei-Min Ren,et al.  Highly Active, Bifunctional Co(III)-Salen Catalyst for Alternating Copolymerization of CO2 with Cyclohexene Oxide and Terpolymerization with Aliphatic Epoxides , 2010 .

[35]  M. S. Larrechi,et al.  Spectroscopic Evidence of the Mechanism Involved in the Cationic Diglycidyl Ether of Bisphenol A Curing with Rare Earth Metal Triflates , 2010, Applied spectroscopy.

[36]  Dae-Won Park,et al.  Effect of complexing agents of double metal cyanide catalyst on the copolymerizations of cyclohexene oxide and carbon dioxide , 2009 .

[37]  Mitsuru Nakamura,et al.  Alternating Copolymerization of Cyclohexene Oxide with Carbon Dioxide Catalyzed by (salalen)CrCl Complexes , 2009 .

[38]  W. Goddard,et al.  Reactions of group III biheterocyclic complexes. , 2009, Journal of the American Chemical Society.

[39]  C. Cramer,et al.  Universal solvation model based on solute electron density and on a continuum model of the solvent defined by the bulk dielectric constant and atomic surface tensions. , 2009, The journal of physical chemistry. B.

[40]  Zhichao Zhang,et al.  Alternating Copolymerization of Cyclohexene Oxide and Carbon Dioxide Catalyzed by Noncyclopentadienyl Rare-Earth Metal Bis(alkyl) Complexes , 2008 .

[41]  P. Diaconescu,et al.  Ring-opening reactions of aromatic N-heterocycles by scandium and yttrium alkyl complexes. , 2008, Journal of the American Chemical Society.

[42]  Z. Hou,et al.  Alternating Copolymerization of Cyclohexene Oxide and Carbon Dioxide Catalyzed by Organo Rare Earth Metal Complexes , 2005 .

[43]  David R. Moore,et al.  Discrete metal-based catalysts for the copolymerization of CO2 and epoxides: discovery, reactivity, optimization, and mechanism. , 2004, Angewandte Chemie.

[44]  David R. Moore,et al.  Mechanism of the alternating copolymerization of epoxides and CO2 using beta-diiminate zinc catalysts: evidence for a bimetallic epoxide enchainment. , 2003, Journal of the American Chemical Society.

[45]  R. McDonald,et al.  Organometallic complexes of scandium and yttrium supported by a bulky salicylaldimine ligand , 2002 .

[46]  F. Edelmann,et al.  Synthesis and structural chemistry of non-cyclopentadienyl organolanthanide complexes. , 2002, Chemical reviews.

[47]  G. Coates,et al.  Single-site beta-diiminate zinc catalysts for the alternating copolymerization of CO2 and epoxides: catalyst synthesis and unprecedented polymerization activity. , 2001, Journal of the American Chemical Society.

[48]  T. Hiyama,et al.  Spectral assignment of poly[cyclohexene oxide-alt-carbon dioxide] , 2001 .

[49]  J. Okuda,et al.  Single-Component Polymerization Catalysts for Ethylene and Styrene: Synthesis, Characterization, and Reactivity of Alkyl and Hydrido Yttrium Complexes Containing a Linked Amido-Cyclopentadienyl Ligand , 2000 .

[50]  A. Becke.  Density-functional thermochemistry. III. The role of exact exchange , 1993 .

[51]  H. Bernhard Schlegel,et al.  An improved algorithm for reaction path following , 1989 .

[52]  H. Lewis,et al.  Association of alkyllithium compounds in hydrocarbon media. Alkyllithium-base interactions , 1970 .

[53]  H. Koinuma,et al.  Copolymerization of carbon dioxide and epoxide with organometallic compounds , 1969 .