Reductively induced dissociation

Reductively induced dissociation of an ancillary ligand from polypyridine complexes has a great importance for redox catalysis ... 

The use of collision-induced dissociation (CID) and MS/MS techniques in conjunction with the API interfaces has dramatically impacted the fleld of environmental analysis. These techniques are now preferred for the determination of triazine compounds in water, soil, crops, etc., owing to the significant improvements in selectivity obtained via the monitoring of precursor-product ion pairs and increased sensitivity due to the reduction of chemical noise. 

Scans based on resonant ejection may either be carried out in a forward, i.e., from low to high mass, or a reverse manner. This allows for the selective storage of ions of a certain m/z value by elimination of ions below and above that m/z value from the trap. Thus, it can serve for precursor ion selection in tandem MS experminents. [156,158] Axial excitation can also be used to cause collision-induced dissociation (CID) of the ions as a result of numerous low-energy collisions with the helium buffer gas that is present in the trap in order to dampen the ion motion. [150,156] A substantial increase of the mass range is realized by reduction of both the RF frequency of the modulation voltage and the physical size of theQIT. [154,159,160]... 

The reduction in concentration of reactants, enzymes, and solute molecules can provide important information about kinetic systems. For example, one can readily differentiate a first-order process from a second-order process by testing whether the period required to reduce a reactant concentration to 50% of its initial value depends on dilution. First-order processes and intramolecular processes should not exhibit any effect on rate by diluting a reactant. In terms of enzyme-catalyzed processes, the Michaelis-Menten equation requires that the initial reaction velocity depends strictly on the concentration of active catalyst. Dilution can also be used to induce dissociation of molecular complexes or to promote depolymerization of certain polymers (such as F-actin and microtubules). 

G. P. Jackson, F. I. King, D. C. Duckworth, Efficient polyatomic interference reduction in plasma source mass spectrometry via collision induced dissociation, J. Anal. Atom. Spectrom., 18 (2003), 1026-1032. 

Generally, the rate and extent of the reductively-induced ancillary ligand dissociation increase with the number of electrons added and decrease with increasing delocalization within the M(N,N) chelate ring. Hence, reduced bpy or phen complexes are much more reactive than those of bpym, Ar-dab or, especially, abpy. 

Automated data processing, data reduction, spectral interpretation, and reporting are also integral parts of open-access sample analysis. Mallis et al. [33] described the use of an open-access system with e-mail capabilities to distribute processed data reports to the chemist. Several methods have been developed, including structure elucidation with in-source collision-induced dissociation (CID). 

Aldehyde CH bonds are reactive in oxidative addition, so it is not unexpected to find that aldehydes readily undergo catalytic reactions involving this oxidative addition. Several catalysts decarbonylate aldehydes as a result of the acyl hydride formed after the C-H addition undergoing deinsertion of CO, followed by reductive elimination of the alkane product (Eq. 2.49). The hard step in the process is the thermally induced dissociation of the resulting tightly bound CO. One such catalyst is [Rh(triphos)Cl] (triphos = PhP(CH2CH2PPh2)2) [134]. 

An ESI-MS/MS study by CID (collision-induced dissociation) of the Suzuki-Miyaura reaction with palladium-diene catalysts showed that in this system, the reductive elimination step determines the rate of the whole process [361],... 

Figure 4 Mass spectra of VKl after reductive acylation with zinc and heptafluorobu-tyric anhydride, using ion trap technology. (A) EI-GC-MS-spectrum (parent ion spectrum). (B) GC-MS-MS daughter ion spectrum of parent ion m/z = 383, using collision-induced dissociation mode (CID). (C) GC-MS-MS daughter ion spectrum of parent ion m/z = 648, also in CID mode (unpublished results).

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