Phenanthroline silver complexes

The cationic complex of silver and 1,10-phenanthroline (phen) has been found to react with Bromopyrogallol Red to yield an ion-associate which can be extracted into nitrobenzene (e = 3.2T0" at 590 nm) [31,32]. The cationic complex, Ag(phen)2 gives ion-associates also with acid dyes, such as Rose Bengal (formula 4.35) and eosin (formula 4.34) (nitrobenzene) [33]. Extractable ion-associates of cationic silver complex with 1,4,8,11-tetrathiacyclotetradecane (crown ether), and various chromogenic anions [34] should also be mentioned. 

Dagnall and West8 have described the formation and extraction of a blue ternary complex, Ag(I)-l,10-phenanthroline-bromopyrogallol red (BPR), as the basis of a highly sensitive spectrophotometric procedure for the determination of traces of silver (Section 6.16). The reaction mechanism for the formation of the blue complex in aqueous solution was investigated by photometric and potentiometric methods and these studies led to the conclusion that the complex is an ion association system, (Ag(phen)2)2BPR2, i.e. involving a cationic chelate complex of a metal ion (Ag + ) associated with an anionic counter ion derived from the dyestuff (BPR). Ternary complexes have been reviewed by Babko.9... 

Discussion. Silver can be extracted from a nearly neutral aqueous solution into nitrobenzene as a blue ternary ion association complex formed between silver(I) ions, 1,10-phenanthroline and bromopyrogallol red. The method is highly selective in the presence of EDTA, bromide and mercury(II) ions as masking agents and only thiosulphate appears to interfere.8... 

Recently, Lacour, Sauvage and coworkers were able to show that the association of chiral [CuL2] complexes (L=2-R-phen,6-R-bpy and2-iminopyridine) with TRISPHAT 8 leads to an NMR enantiodifferentiation, which allows the determination of the kinetics of racemization of the complexes (bpy=2,2 -bipyri-dine phen=l,10-phenanthroline) [119]. This type of application has recently been reported in conjunction with chiral sandwich-shaped trinuclear silver(l) complexes [122]. Several reports, independent from Lacour s group,have confirmed the efficiency of these chiral shift agents [123-127]. Finally, TRISPHAT can be used to determine the enantiomeric purity of (r] -arene)chromium complexes. These results broaden the field of application of 8 to chiral neutral, and not just cationic, species [114,128,129]. 

The reactions of alcohols related to phenolphthalein and fluorescein with Ag1 ions have been investigated for their application as colorimetric reagents in determining trace amounts of silver. A simple, rapid and sensitive method was found which used 2,4,5,7-tetra-bromofluorescein and 1,10-phenanthroline. A ternary complex was formed with a deep pink colour (Ama 550 nm) in the presence of silver(I) ions and the two reagents. No significant colour change was observed in the absence of the diimine.227... 

Mono and bis 2,2 -bipyridyl and 1,10-phenanthroline complexes of silver(II) have been isolated as red-brown crystals by either peroxydisulfate, anodic or ozone oxidation techniques.497,519 No tris-chelated species have been substantiated,497 although it is worth noting that a 2,2, 2"-terpyridyl bis complex has been isolated and claimed to be a six-coordinate... 

The silver-silver distance is 3.386 A, indicating a weak silver-silver interaction (Fig. 6.3). Observing the disilver structure for the second time, the authors studied the importance of the disilver structure on reactivity. By testing different phenanthrolines, they found that 2,9-substituted phenanthrolines did not catalyze the amination reaction. This result was supported by structural evidence—the silver-2,9-dimethyl-phenanthroline complex did not form disilver structure two ligands coordinated one silver in a tetrahedral geometry, blocking the approach of any other molecule to the silver center. Even one bulky mesityl group in the 2 position inhibits the reactivity completely (Scheme 6.6). 

The self-assembly of a new category of tetranuclear complexes of both copper(I) and silver(I) has been reported. Interaction of these metal ions with the (bis)bipyri-dine-based macrocycle 34 (Figure 6.17), incorporating phenanthroline pendant arms, results in the assembly of 4 2 (metal ligand) complexes incorporating four helical domains. An X-ray diffraction study of the species of type showed... 

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