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Paul G. Hayes

Bio: Paul G. Hayes is an academic researcher from University of Lethbridge. The author has contributed to research in topics: Ligand & Cationic polymerization. The author has an hindex of 28, co-authored 73 publications receiving 2994 citations. Previous affiliations of Paul G. Hayes include University of British Columbia & University of Calgary.


Papers
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Journal ArticleDOI
TL;DR: This Perspective is not intended as a comprehensive review, but rather a systematic highlight of key contributions, which have served to extend the forefront of this exciting field.
Abstract: Interest in the utility of polylactide as a commodity polymer has increased significantly in recent years due to numerous environmental advantages over conventional petrochemically derived plastics. As such, the development of novel catalyst systems for the ring opening polymerization of lactide has seen tremendous progress in the past decade. In particular, divalent metals (i.e.Mg, Ca and Zn) supported by monoanionic ancillary scaffolds are appealing because of their low toxicity and cost. A much less common approach involves the use of neutral ligands in combination with the aforementioned divalent metal centres. The additional valence thus renders it possible, upon reaction with traditional Lewis or Bronsted acid activators, to generate sterically and electronically unsaturated species, akin to the most widely employed olefin polymerization catalysts. This Perspective is not intended as a comprehensive review, but rather a systematic highlight of key contributions, which have served to extend the forefront of this exciting field.

406 citations

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TL;DR: The synthetic development of silylene ligands in the laboratory and resulting investigations of stoichiometric and catalytic chemistry for these species are described.
Abstract: A variety of transition-metal complexes with terminal silylene ligands have become available in recent years, because of the discovery of several preparative methods. In particular, three general synthetic routes to these complexes have emerged, on the basis of anionic group abstraction, coordination of a free silylene, and α-hydrogen migration. The direct transformation of organosilanes to silylene ligands at a metal center (silylene extrusion) has also been observed, and this has further spurred the exploration of silylenes as ligands. This Account describes the synthetic development of silylene ligands in our laboratory and resulting investigations of stoichiometric and catalytic chemistry for these species.

289 citations

Journal ArticleDOI
TL;DR: Several diorganoscandium complexes stabilized by the β-diketiminato ligands (Ar)NC(R)CHC(R),N(Ar) (Ar = 2,6-iPr-C6H3; R = CH3 (ligand a), R = tBu (ligands b)) have been synthesized as discussed by the authors.

198 citations

Journal ArticleDOI
TL;DR: Dimethyl compound 1 is a highly active catalyst precursor for ethylene polymerization under borane or MAO-type activation and activities for this group 3 metal based catalyst approach those observed for group 4 based metallocene systems.
Abstract: The base-free dimethyl scandium complex supported by the bulky β-diketiminato ligand ArNC(tBu)CHC(tBu)NAr (Ar = 2,6-iPr2C6H3, 1) reacts with various equivalencies of the strong organometallic Lewis acid B(C6F5)3 to give scandium alkyl cations. With 0.5 equiv, a monocationic μ-methyl dimer (2) was observed spectroscopically. Reaction with a further 0.5 equiv of borane gives the monomeric methyl cation 3, which was fully characterized, including via X-ray crystallography. This compound is fluxional on the NMR time scale via a “ligand flip” mechanism. Reaction with another equivalent of borane gives the unique dication 4, which exhibits a static structure on the NMR time scale. Dimethyl compound 1 is a highly active catalyst precursor for ethylene polymerization under borane or MAO-type activation. Activities for this group 3 metal based catalyst approach those observed for group 4 based metallocene systems.

187 citations

Journal ArticleDOI
TL;DR: The scandium-catalyzed intramolecular hydroamination of alkynes and alkenes was reported in this article, where complex structure/catalyst activity investigations resulted in the identification of a highly catalytically active cationic, β-diketiminato Scandium complex.

160 citations


Cited by
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Journal ArticleDOI
10 Mar 1970

8,159 citations

Journal ArticleDOI
TL;DR: The graph below shows the progression of monoanionic and non-monoanionic ligands through the history of synthesis, as well as some of the properties that have been identified since the discovery of R-Diimine.
Abstract: B. Anionic Ligands 302 IX. Group 9 Catalysts 302 X. Group 10 Catalysts 303 A. Neutral Ligands 303 1. R-Diimine and Related Ligands 303 2. Other Neutral Nitrogen-Based Ligands 304 3. Chelating Phosphorus-Based Ligands 304 B. Monoanionic Ligands 305 1. [PO] Chelates 305 2. [NO] Chelates 306 3. Other Monoanionic Ligands 306 4. Carbon-Based Ligands 306 XI. Group 11 Catalysts 307 XII. Group 12 Catalysts 307 XIII. Group 13 Catalysts 307 XIV. Summary and Outlook 308 XV. Glossary 308 XVI. References 308

2,369 citations

Journal ArticleDOI
TL;DR: Investigations revealed that the conversion of C-H bonds to C-B bonds was both thermodynamically and kinetically favorable and highlighted the accessible barriers for C- H bond cleavage and B-C bond formation during the borylation of alkanes and arenes.
Abstract: A number of studies were conducted to demonstrate C-H activation for the construction of C-B bonds. Investigations revealed that the conversion of C-H bonds to C-B bonds was both thermodynamically and kinetically favorable. The reaction at a primary C-H bond of methane or a higher alkene B 2(OR)4 formed an alkylboronate ester R' -B(OR)2 and the accompanying borane H-B(OR2. The ester and the borane were formed on the basis of calculated bond energies for methylboronates and dioaborolanes. The rates of key steps along the reaction pathway for the conversion of a C-H bond in an alkane or arene to the C-B bond in an alkyl or arylboronate ester were favorable. These studies also highlighted the accessible barriers for C-H bond cleavage and B-C bond formation during the borylation of alkanes and arenes.

2,108 citations

Journal ArticleDOI
TL;DR: Hydroamination of Alkenes and Alkynes under Microwave Irradiation and Nitromercuration Reactions 3878 9.8.4.5.
Abstract: 8.4.5. Nitromercuration Reactions 3878 9. Hydroamination of Alkenes and Alkynes under Microwave Irradiation 3878 * To whom correspondence should be addressed. Phone: +49 241 8

1,685 citations

Journal ArticleDOI
TL;DR: A comprehensive overview on first row transition metal catalysts for C-H activation until summer 2018 is provided.
Abstract: C–H activation has surfaced as an increasingly powerful tool for molecular sciences, with notable applications to material sciences, crop protection, drug discovery, and pharmaceutical industries, among others. Despite major advances, the vast majority of these C–H functionalizations required precious 4d or 5d transition metal catalysts. Given the cost-effective and sustainable nature of earth-abundant first row transition metals, the development of less toxic, inexpensive 3d metal catalysts for C–H activation has gained considerable recent momentum as a significantly more environmentally-benign and economically-attractive alternative. Herein, we provide a comprehensive overview on first row transition metal catalysts for C–H activation until summer 2018.

1,417 citations