Chromium complex compounds structure

TLC has been applied for the purity control of the newly synthetized o,o -dihydrox-yazo dyes and their chromium complexes. The structures of 7-hydroxy-o,o -dihydrox-yazo dyes and their chromium complexes are listed in Fig. 3.14. TLC purity check of o,o -dihydroxyazo dyes and their chromium complexes was performed on silica layers using 5 per cent water/ethanol and 5 per cent water-dimethylsulphoxide as the mobile phase, respectively. The formula and Rp values of 7-hydroxy-o//-dihydroxyazo dyes and their chromium complexes are compiled in Table 3.10. The retention values indicated that the TLC technique applied is suitable for the purity control of the these new dye compounds [92],... 

Rather complex structures are obtained by a novel chromium(O)-mediated three-component domino [6jt+2jt] cycloaddition described by Rigby and coworkers [315]. Irradiation of a mixture of the chromium complex 6/4-134 and the tethered diyne 6/4-135 with a Pyrex filter at 0 °C gave the polycyclic compounds 6/4-136 in medium to good yield (Scheme 6/4.34). 

In 1939, Drew83 proposed structures for 2 1 chromium complexes of o,octahedrally coordinated to the central chromium ion (81). Pfitzner71 independently arrived at the same conclusion and 2 1 chromium complexes having this equatorial or meridional (mer) configuration have been described84 as Drew—Pfitzner types. This configuration permits only an enantiomeric pair of isomers. 

Support for Schetty s postulates has been provided by X-ray crystal structure determinations. Thus the 2 1 chromium complexes (126) and (127) of the two o,o -dihydroxydiarylazo compounds 2,2 -dihydroxyazobenzene and l-(2-hydroxy-4-nitrophenylazo)-2-naphthol, respectively, have been proved89 to have meridional configurations, whilst the 2 1 chromium complex (128) of the o-carboxyarylazopyrazolone l-(4-brornophenyl)-3-methyl-4-(2-methyl-6-carboxyphenylazo)-5-pyrazolone has been proved90 to have a facial configuration. 

Reactions of metal carbonyls with Zintl phases do not always yield the desired result. An example is the reaction of KSi with the metal carbonyls M(CO)6 (M = Cr, Mo, W) and the chromium complex Cr(CO)sNMe3. Instead of forming a structure with a Si4 anion, KSi reduces these transition metal compounds to form the anions, [M2(CO)io] . In addition, certain organometallic transition metal clusters have been synthesized that contain Zintl anions coordinated to the metal, but Zintl compounds are not used as the reagents. 

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