Substituent effect on wave numbers of C=O valence vibrations in ferrocene derivatives

1983 ◽  
Vol 48 (6) ◽  
pp. 1635-1646 ◽  
Author(s):  
Alexander Perjéssy ◽  
Štefan Toma
Keyword(s):  
Linear Correlation ◽  
Substituent Effect ◽  
Empirical Relation ◽  
Ferrocene Derivatives ◽  
Wave Numbers ◽  
Complex Structural ◽  
Transmission Factors

Wave numbers of C=O valence vibrations of 83 ferrocene derivatives have been measured in tetrachloromethane. For a series of 154 compounds containing ferrocene skeleton linear correlation has been found between wave numbers of C=O vibration and X+(R) constants of structural fragments in the sense of modified and extended Seth-Paul-Van Duyse equation. Validity has been verified of the recently derived empirical relation for calculation of the X+(R) constants of complex structural fragments from values of constants of substituents and transmission factors for simple structural groupings. The transmission factors γ and π' for 1,3- and 1,1'-ferrocene system have been found to be well applicable to calculation of constants of structural fragments containing ferrocene skeleton.

New Finite Element Modeling Strategy for Large-Scale Industrial Problems in Structural Acoustics

2000 ◽  
Author(s):  
Saikat Dey ◽  
Luise S. Couchman
Keyword(s):  
Finite Element ◽  
Finite Element Modeling ◽  
Large Scale ◽  
Structural Acoustics ◽  
Simple Scheme ◽  
Numerical Examples ◽  
High Wave ◽  
Wave Numbers ◽  
Complex Structural ◽  
Modeling Strategy

Abstract A simple scheme to model and mesh stiffened shell-like structures is presented. Combined with a high-order finite/infinite element based infrastructure, it enables the solution of complex structural acoustics problems at high wave numbers. Numerical examples are presented to show the applicability of the method at high wave-numbers.

scholarly journals The observation of ion-pairing effect based on substituent effect of ferrocene derivatives

2015 ◽  
Vol 757 ◽  
pp. 258-262 ◽  
Author(s):  
Yujie Shi ◽  
Liu Fang ◽  
Xuan Li ◽  
Liangti Qu ◽  
Huibo Shao
Keyword(s):  
Substituent Effect ◽  
Ion Pairing ◽  
Ferrocene Derivatives ◽  
Pairing Effect

scholarly journals Synthesis, UV/vis spectra and electrochemical characterisation of arylthio and styryl substituted ferrocenes

2011 ◽  
Vol 9 (4) ◽  
pp. 610-618 ◽  
Author(s):  
Thomas Sørensen ◽  
Merete Nielsen
Keyword(s):  
Cyclic Voltammetry ◽  
Absorption Spectroscopy ◽  
Substituent Effect ◽  
Electronic Communication ◽  
Substituent Effects ◽  
Para Position ◽  
Electronic Transitions ◽  
Ferrocene Derivatives ◽  
Order Of Magnitude ◽  
Electrochemical Characterisation

AbstractTwo series of substituted ferrocenes were synthesised using either the Horner-Wadsworth-Emmons reaction or monolithiation of ferrocene. The series consist of arylthio- and styryl-ferrocenes with different substituents in the para position of the aryl rings of the systems. The electronic communication was investigated by comparing the substituent effects in absorption spectroscopy and in cyclic voltammetry. A small substituent effect was found in the electronic transitions of the styryl substituted ferrocenes. The oxidation of the ferrocene derivatives showed clear substituent effects as illustrated by the linear Hammett plots. The effect was shown to be an order of magnitude larger in the arylthio-systems than in the styryl systems. It is suggested that the reason behind the large effect is a direct sulfur-iron orbital overlap.

The wavenumbers of NO2 stretching vibrations and transmission of substituent effects in 2- and 4-substituted 3-nitropyridine series

1985 ◽  
Vol 50 (11) ◽  
pp. 2443-2452 ◽  
Author(s):  
Alexander Perjéssy ◽  
Danuta Rasala ◽  
Piotr Tomasik ◽  
Ryszard Gawinecki
Keyword(s):  
Nitro Group ◽  
Substituent Effect ◽  
Substituent Effects ◽  
Correlation Equations ◽  
Stretching Vibration ◽  
Stretching Vibrations ◽  
Transmission Factors

The wavenumbers of both the symmetric and asymmetric stretching vibrations of the nitro group were measured in chloroform for the series of 2-X- and 4-X-substituted 3-nitropyridines as well as for o-X-substituted nitrobenzenes. The νas(NO2) and νs(NO2) values of both nitropyridine series were compared with those of corresponding nitrobenzenes. It has been found that the substituent effects in pyridines are transmitted to the 3-nitro group more readily from the 4-position, than from the 2-position. This transmission in 2-X-substituted 3-nitropyridines is comparable with that in the series of o-substituted benzene analogues. The transmission factors, γ, were determined according to Charton's definition for both 2,3- and 4,3-disubstituted pyridine rings. The separation of overall substituent effect into its inductive (field), resonance and steric components is discussed in terms of multiparameter correlation equations for wavenumber of asymmetric NO2 stretching vibration.

Preparation of 3-cyano-4-(R-vinyl)-5,5-dimethyl-Δ3-butenolides and substituent effects on their infrared spectra

1989 ◽  
Vol 54 (6) ◽  
pp. 1666-1674 ◽  
Author(s):  
Alexander Perjéssy ◽  
Aida Avetisovna Avetisyan ◽  
Anna Alexandrovna Aknazaryan ◽  
Gagik Surenovich Melikyan
Keyword(s):  
Infrared Spectra ◽  
Substituent Effects ◽  
Aromatic Aldehydes ◽  
The Other ◽  
Wave Numbers ◽  
Different Types ◽  
Group A ◽  
Stretching Vibrations ◽  
Transmission Factors ◽  
Statistical Results

Twenty nine 3-cyano-4-(R-vinyl)-5,5-dimethyl-Δ3-butenolides were prepared by condensation of 3-cyano-4,5,5-trimethyl-Δ3-butenolide with aliphatic and aromatic aldehydes. The wave numbers of C=O, C=N and C=C stretching vibrations of synthesized compounds were measured in trichloro- and tetrachloromethane. The spectral data were correlated with substituent conotants using Hammett-Brown and the improved and extended Seth-Paul-Van Duyse equation. The statistical results of correlations were compared with those of ethyl α-cyanocinnamates, ethyl benzoates and benzonitriles. The transmission factors for one and two C=C bonds were determined in the regions of π' = 0.46-0.57 and 0.27-0.37, respectively. In 3-cyano-4-(arylvinyl)-5,5-dimethyl-Δ3-butenolides a considerable conjugation exists between the arylvinyl moiety and both the C=O and C=N groups. On the other hand, in 3-cyano-4-(alkylvinyl)-5,5-dimethyl-Δ3-butenolides probably only the endocyclic C=C bond takes part in a marked resonance interaction with alkylvinyl group. A generally valid relationship was found between the slopes of ν(C=O) vs σ+ and ν(C=N) vs σ+ correlations for different types of compounds measured in CHCl3 and CCl4.

Strongly Coupled Redox-Linked Conformational Switching at the Active Site of the Non-Heme Iron-Dependent Dioxygenase, TauD

2019 ◽  
Author(s):  
Christopher John ◽  
Greg M. Swain ◽  
Robert P. Hausinger ◽  
Denis A. Proshlyakov
Keyword(s):  
Active Site ◽  
Structural Model ◽  
Heme Iron ◽  
Chemical Transformations ◽  
Experimental Conditions ◽  
Strongly Coupled ◽  
Non Heme Iron ◽  
Reversible Redox ◽  
Wide Range ◽  
Complex Structural

2-Oxoglutarate (2OG)-dependent dioxygenases catalyze C-H activation while performing a wide range of chemical transformations. In contrast to their heme analogues, non-heme iron centers afford greater structural flexibility with important implications for their diverse catalytic mechanisms. We characterize an <i>in situ</i> structural model of the putative transient ferric intermediate of 2OG:taurine dioxygenase (TauD) by using a combination of spectroelectrochemical and semi-empirical computational methods, demonstrating that the Fe (III/II) transition involves a substantial, fully reversible, redox-linked conformational change at the active site. This rearrangement alters the apparent redox potential of the active site between -127 mV for reduction of the ferric state and 171 mV for oxidation of the ferrous state of the 2OG-Fe-TauD complex. Structural perturbations exhibit limited sensitivity to mediator concentrations and potential pulse duration. Similar changes were observed in the Fe-TauD and taurine-2OG-Fe-TauD complexes, thus attributing the reorganization to the protein moiety rather than the cosubstrates. Redox difference infrared spectra indicate a reorganization of the protein backbone in addition to the involvement of carboxylate and histidine ligands. Quantitative modeling of the transient redox response using two alternative reaction schemes across a variety of experimental conditions strongly supports the proposal for intrinsic protein reorganization as the origin of the experimental observations.

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