Reactions of transition metal-nitrogen .sigma. bonds. 4. Mechanistic studies of carbon dioxide insertion and carbon dioxide exchange reactions involving early transition metal dimethylamido and N,N-dimethylcarbamato compounds

1977 ◽  
Vol 99 (3) ◽  
pp. 792-802 ◽  
Author(s):  
Malcolm H. Chisholm ◽  
Michael W. Extine
Keyword(s):  
Carbon Dioxide ◽  
Transition Metal ◽  
Carbon Dioxide Exchange ◽  
Mechanistic Studies ◽  
Exchange Reactions ◽  
Early Transition Metal ◽  
Sigma Bonds ◽  
Early Transition

scholarly journals How bulk and surface properties of Ti4SiC3, V4SiC3, Nb4SiC3 and Zr4SiC3 tune reactivity: A computational study

2021 ◽  
Author(s):  
Matthew Quesne ◽  
C. Richard A. Catlow ◽  
Nora Henriette De Leeuw
Keyword(s):  
Carbon Dioxide ◽  
Transition Metal ◽  
Surface Properties ◽  
In Silico ◽  
Computational Study ◽  
Max Phase ◽  
Early Transition Metal ◽  
Silicon Carbides ◽  
Carbon Dioxide Hydrogenation ◽  
Early Transition

We present several in silico insights into the MAX-phase of early transition metal silicon carbides and explore how these affect carbon dioxide hydrogenation. Periodic desity functional methodology is applied to...

scholarly journals Ti Catalyzed Hydroamination: A Direct Functionalization of Cu Acetylide

2019 ◽  
Author(s):  
Han Hao ◽  
Laurel Schafer
Keyword(s):  
Nmr Spectroscopy ◽  
Transition Metal ◽  
Single Crystal ◽  
Mechanistic Studies ◽  
Single Crystal Diffraction ◽  
X Ray ◽  
Early Transition Metal ◽  
Direct Functionalization ◽  
Metal Catalyzed ◽  
Early Transition

In the presence of a bis-amidate-bis-amido Ti pre-catalyst, an NHC supported Cu acetylide was reacted with <i>p</i>-toluidine to generate a new Cu containing species almost quantitatively. The product was analyzed by NMR spectroscopy and X-ray single crystal diffraction to be a Cu enamide. Preliminary mechanistic studies suggest the reaction follows well accepted [2+2] cycloaddition mechanism for early transition metal catalyzed hydroamination. Furthermore, the reaction is likely to be a direct functionalization of the alkyne moiety of the Cu acetylide.

scholarly journals Ti Catalyzed Hydroamination: A Direct Functionalization of Cu Acetylide

2019 ◽  
Author(s):  
Han Hao ◽  
Laurel Schafer
Keyword(s):  
Nmr Spectroscopy ◽  
Transition Metal ◽  
Single Crystal ◽  
Mechanistic Studies ◽  
Single Crystal Diffraction ◽  
X Ray ◽  
Early Transition Metal ◽  
Direct Functionalization ◽  
Metal Catalyzed ◽  
Early Transition

In the presence of a bis-amidate-bis-amido Ti pre-catalyst, an NHC supported Cu acetylide was reacted with <i>p</i>-toluidine to generate a new Cu containing species almost quantitatively. The product was analyzed by NMR spectroscopy and X-ray single crystal diffraction to be a Cu enamide. Preliminary mechanistic studies suggest the reaction follows well accepted [2+2] cycloaddition mechanism for early transition metal catalyzed hydroamination. Furthermore, the reaction is likely to be a direct functionalization of the alkyne moiety of the Cu acetylide.

scholarly journals Chain Transfer to Solvent and Monomer in Early Transition Metal Catalyzed Olefin Polymerization: Mechanisms and Implications for Catalysis

Catalysts ◽  
2021 ◽  
Vol 11 (2) ◽  
pp. 215
Author(s):  
Francesco Zaccaria ◽  
Peter H. M. Budzelaar ◽  
Cristiano Zuccaccia ◽  
Roberta Cipullo ◽  
Alceo Macchioni ◽  
...  
Keyword(s):  
Transition Metal ◽  
Chain Transfer ◽  
Olefin Polymerization ◽  
Transfer Reactions ◽  
Organic Radical ◽  
Mechanistic Studies ◽  
Early Transition Metal ◽  
Polymerization Catalysis ◽  
Insertion Polymerization ◽  
Early Transition

Even after several decades of intense research, mechanistic studies of olefin polymerization by early transition metal catalysts continue to reveal unexpected elementary reaction steps. In this mini-review, the recent discovery of two unprecedented chain termination processes is summarized: chain transfer to solvent (CTS) and chain transfer to monomer (CTM), leading to benzyl/tolyl and allyl type chain ends, respectively. Although similar transfer reactions are well-known in radical polymerization, only very recently they have been observed also in olefin insertion polymerization catalysis. In the latter context, these processes were first identified in Ti-catalyzed propene and ethene polymerization; more recently, CTS was also reported in Sc-catalyzed styrene polymerization. In the Ti case, these processes represent a unique combination of insertion polymerization, organic radical chemistry and reactivity of a M(IV)/M(III) redox couple. In the Sc case, CTS occurs via a σ-bond metathesis reactivity, and it is associated with a significant boost of catalytic activity and/or with tuning of polystyrene molecular weight and tacticity. The mechanistic studies that led to the understanding of these chain transfer reactions are summarized, highlighting their relevance in olefin polymerization catalysis and beyond.

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