Substituent Effects on Haptotropic Rearrangements of Bis(indenyl)zirconium Sandwich Complexes

2006 ◽  
Vol 25 (9) ◽  
pp. 2266-2273 ◽  
Author(s):  
Luis F. Veiros
Keyword(s):  
Substituent Effects ◽  
Sandwich Complexes ◽  
Haptotropic Rearrangements

Substituent effects on the electronic structures of sandwich compounds: new understandings provided by DFT-assisted laser ionization spectroscopy of bisarene complexes

2020 ◽  
Vol 49 (3) ◽  
pp. 569-577 ◽  
Author(s):  
Sergey Ketkov
Keyword(s):  
High Resolution ◽  
Transition Metal ◽  
Electronic Structures ◽  
Substituent Effects ◽  
Laser Ionization ◽  
Sandwich Complexes ◽  
Threshold Ionization ◽  
Sandwich Compounds

High-resolution threshold ionization spectroscopy reveals new aspects of substituent effects in transition-metal sandwich complexes.

Substituent effects in bis(arene)chromium compounds containing a CN group in the aromatic ring

2005 ◽  
Vol 61 (3) ◽  
pp. 304-311 ◽  
Author(s):  
Victor N. Khrustalev ◽  
Alexander Yu. Vasil'kov ◽  
Mikhail Yu. Antipin
Keyword(s):  
Torsion Angle ◽  
Substituent Effects ◽  
Metal Vapor ◽  
X Ray Diffraction ◽  
Aromatic Rings ◽  
Ring Plane ◽  
Sandwich Complexes ◽  
X Ray ◽  
Intermolecular Contacts ◽  
Chromium Compounds

The crystal structures of Cr(PhCN)2 (2), (PhCN)Cr(PhCH3) (3) and (PhCN)Cr(PhCF3) (4) prepared by means of the Metal Vapor Synthesis (MVS) technique have been determined. Compounds (2), (3) and (4) crystallize as discrete sandwich complexes having intrinsic C 2v (mm2), C s (m) and C 1(1) symmetries, respectively. The X-ray diffraction study has revealed a synperiplanar conformation for (2) and (3), and a synclinal conformation for (4) with a torsion angle (C ipso 1–Centroid1–Centroid2–C ipso 2) of φ = 63.5°. The angles between the ligand planes are 2.2, 3.9 and 1.8°, respectively. The Cr atom is slightly (by 0.04–0.06 Å) displaced towards the substituents from the line connecting the centers of the opposite aromatic rings. The Cr—C ipso distances are 2.115 (2)–2.137 (2), 2.112 (2) and 2.185 (3) Å for CN, CF3 and CH3 groups, respectively. The CN groups as well as the H atoms lie out of the C 6 ring planes and are bent towards the Cr atom, but the C atom of the CH3 group also lying out of the C6 ring plane is bent away from the Cr atom. The C atom of the CF3 group is essentially coplanar to the C 6 ring plane. There are no unusual intermolecular contacts in the structures of (2)–(4).

Trimethylsilyl-Substituted Indenyl-TiCl3Half-Sandwich Complexes:  Synthesis, Solid-State Structure, and Analysis of Substituent Effects

2005 ◽  
Vol 24 (11) ◽  
pp. 2577-2581 ◽  
Author(s):  
Thomas Weiss ◽  
Uwe Böhme ◽  
Bernhard Walfort ◽  
Gerd Rheinwald ◽  
Heinrich Lang
Keyword(s):  
Solid State ◽  
Substituent Effects ◽  
State Structure ◽  
Sandwich Complexes ◽  
Solid State Structure

Ligand-Induced Haptotropic Rearrangements in Bis(indenyl)zirconium Sandwich Complexes

2005 ◽  
Vol 127 (29) ◽  
pp. 10291-10304 ◽  
Author(s):  
Christopher A. Bradley ◽  
Emil Lobkovsky ◽  
Ivan Keresztes ◽  
Paul J. Chirik
Keyword(s):  
Sandwich Complexes ◽  
Haptotropic Rearrangements

Fine Substituent Effects in Sandwich Complexes: A Threshold Ionization Study of Monosubstituted Chromium Bisarene Compounds

2016 ◽  
Vol 22 (14) ◽  
pp. 4690-4694 ◽  
Author(s):  
Sergey Yu. Ketkov ◽  
Gennady V. Markin ◽  
Sheng Y. Tzeng ◽  
Wen B. Tzeng
Keyword(s):  
Substituent Effects ◽  
Sandwich Complexes ◽  
Threshold Ionization

Substituent effects and solvents

1992 ◽  
Vol 89 ◽  
pp. 1567-1571
Author(s):  
O Pytela ◽  
M Ludwig
Keyword(s):  
Substituent Effects

Substituent Effects on the Thermal Decomposition of Phosphate Esters on Ferrous Surfaces

2019 ◽  
Author(s):  
James Ewen ◽  
Carlos Ayestaran Latorre ◽  
Arash Khajeh ◽  
Joshua Moore ◽  
Joseph Remias ◽  
...  
Keyword(s):  
Thermal Decomposition ◽  
Film Formation ◽  
Substituent Effects ◽  
Vapour Phase ◽  
Industrial Applications ◽  
Phosphate Esters ◽  
Antiwear Additives ◽  
Formation Mechanisms ◽  
Phosphate Ester ◽  
Wide Range

<p>Phosphate esters have a wide range of industrial applications, for example in tribology where they are used as vapour phase lubricants and antiwear additives. To rationally design phosphate esters with improved tribological performance, an atomic-level understanding of their film formation mechanisms is required. One important aspect is the thermal decomposition of phosphate esters on steel surfaces, since this initiates film formation. In this study, ReaxFF molecular dynamics simulations are used to study the thermal decomposition of phosphate esters with different substituents on several ferrous surfaces. On Fe<sub>3</sub>O<sub>4</sub>(001) and α-Fe(110), chemisorption interactions between the phosphate esters and the surfaces occur even at room temperature, and the number of molecule-surface bonds increases as the temperature is increased from 300 to 1000 K. Conversely, on hydroxylated, amorphous Fe<sub>3</sub>O<sub>4</sub>, most of the molecules are physisorbed, even at high temperature. Thermal decomposition rates were much higher on Fe<sub>3</sub>O<sub>4</sub>(001) and particularly α-Fe(110) compared to hydroxylated, amorphous Fe<sub>3</sub>O<sub>4</sub>. This suggests that water passivates ferrous surfaces and inhibits phosphate ester chemisorption, decomposition, and ultimately film formation. On Fe<sub>3</sub>O<sub>4</sub>(001), thermal decomposition proceeds mainly through C-O cleavage (to form surface alkyl and aryl groups) and C-H cleavage (to form surface hydroxyls). The onset temperature for C-O cleavage on Fe<sub>3</sub>O<sub>4</sub>(001) increases in the order: tertiary alkyl < secondary alkyl < primary linear alkyl ≈ primary branched alkyl < aryl. This order is in agreement with experimental observations for the thermal stability of antiwear additives with similar substituents. The results highlight surface and substituent effects on the thermal decomposition of phosphate esters which should be helpful for the design of new molecules with improved performance.</p>

Chemistry of Unsymmetrical C1-Substituted Oxabenzonorbornadienes

2021 ◽  
Vol 17 ◽  
Author(s):  
Austin Pounder ◽  
Angel Ho ◽  
Matthew Macleod ◽  
William Tam
Keyword(s):  
Transition Metal ◽  
Metal Complexes ◽  
Transition Metal Complexes ◽  
Substituent Effects ◽  
Face Selectivity ◽  
Transition Metal Catalyzed ◽  
Catalyzed Reactions ◽  
Metal Catalyzed ◽  
Synthetic Intermediate

: Oxabenzonorbornadiene (OBD) is a useful synthetic intermediate which can be readily activated by transition metal complexes with great face selectivity due to its dual-faced nature and intrinsic angle strain on the alkene. To date, the understanding of transition-metal catalyzed reactions of OBD itself has burgeoned; however, this has not been the case for unsymmetrical OBDs. Throughout the development of these reactions, the nature of C1-substituent has proven to have a profound effect on both the reactivity and selectivity of the outcome of the reaction. Upon substitution, different modes of reactivity arise, contributing to the possibility of multiple stereo-, regio-, and in extreme cases, constitutional isomers which can provide unique means of constructing a variety of synthetically useful cyclic frameworks. To maximize selectivity, an understanding of bridgehead substituent effects is crucial. To that end, this review outlines hitherto reported examples of bridgehead substituent effects on the chemistry of unsymmetrical C1-substituted OBDs.

Sign in / Sign up

Export Citation Format

Share Document