Pyridines, ligands

The reversible formation of a complex by Ni ions and the bi dentate ligand pyridine-2-azo-p-dimethylaniline is a simple and thus reliable reaction, not accompanied by side reactions [17]. Kinetic rate law and rate constants for the reaction are known. The time demand of the reaction fits the short time scales typical for micro reactors. The strong absorption and the strong changes by reaction facilitate analysis of dynamic and spatial concentration profiles. 

Efficient epoxidation of a variety of linear and cyclic alkenes by RuClj/aq. Na(IO )/(bpy)/CH2CyO-5°C/15 h was observed [735] 5-methyl- or 3,4,7,8-tetram-ethyl-phenanthroline can replace (bpy) [736], The active species when (bpy) is present is probably franx-Ru(0)2(bpy) 103(011)3 [567, 568], Competition between epoxidation and cleavage of fran -stilbene with bidentate ligands (pyridine, oxazo-line, oxazolidine and thiophene), containing two different nitrogen heterocycles either linked or separated by a spacer together with RuCyaq. Na(IO )/CH3Cy2°C was reported [737],... 

In general, free ligand pyridines show a great reluctance to take part in electrophilic substitution reactions. Forcing conditions are frequently required, and low yields and specificity are normally observed. In principle, co-ordination to a metal ion capable of back-donation should increase the tendency for electrophilic attack, since back-donation results in an increase in n electron density. 

How many geometrical isomers could [Rh(py)3Cl3] have The abbreviation py is for the ligand pyridine. 

Picolinic acid (pyridine 2-carboxylic acid) is the prototype for this type of ligand. Pyridine itself does not react favorably with vanadate, nor do the 3 and 4 pyridine carboxylates. At first sight, one would expect that 2-hydroxypyridine would react favorably with vanadate, but this is not true. There are two likely explanations for this. First, the 2-hydroxypyridine exists predominantly as the keto tautomer, so the effective concentration of the hydroxylate is low. The keto form of the ligand can be expected to be much less reactive than the hydroxyl form. Second, the formation... 

PTV PU PVA PVAC PVAL PVC PVDC PVDF PVE PVF PXRD py Py PY Py-GC-MS pyr pyrr pz programmed-temperature vaporizer polyurethane poly (vinyl alcohol) poly(vinyl acetate) poly (vinyl alcohol) poly (vinyl chloride) poly(vinylidene dichloride) poly(vinylidene difluoride) poly (vinyl ether) poly(vinyl fluoride) powder X-ray diffraction pyridine (ligand) pyridine pyramidal (coordination compounds) pyrolysis-gas chromatography-mass spectrometry pyrazine (ligand) pyrrolidine (ligand) pyrazole (ligand)... 

In the absence of a donor ligand, BD is trimerized to a mixture of three isomers of 1,5,9-CDT with the [ -trans isomer being the principal product [6, 7]. Addition of donor ligands (pyridine is an exception) leads to considerable BD-cyclodimer-ization. Table 2 [7, 14] shows the results of a study of the effects of varying the ligand on the cyclodimer/cyclotrimer ratio (see also Table 1). 

PXRD py py PY Py-GC-MS pvr pyrr Pz a powder X-ray diffraction pyridine (ligand) pyridine pyramidal (coordination compounds) pyrolysis—gas chromatography—mass spectrometry pyrazine (ligand) pyrrolidine (ligand) pyrazole (ligand)... 

---