Zur Frage der Existenz von Stereoisomeren bei Metall‐8‐hydroxychinolinaten. III. Über Additionsverbindungen des Tris‐(8‐hydroxychinolinato)‐chrom(III) mit Alkoholen, Äthern und Aminen

Abstract

Darstellungsmethoden für die beiden stereoisomeren Tris‐(8‐hydroxychinolinato‐) chrom(III)‐Komplexe werden angegeben. Auf Grund von Modellvorstellungen wird der solvatbildenden Form die „cis‐fac”︁‐Struktur, der oberhalb 125°C entstehenden nicht‐solvatbildenden Form die „trans‐mer”︁‐Struktur zugeschrieben. Durch Bildung von Additionsverbindungen wird die cis‐Form, je nach Art des Addenden, auf 170–220°C stabilisiert. Additionsverbindungen des cis‐CrOx3 mit folgenden Verbindungen wurden rein dargestellt und untersucht: 1:2‐Typ: Wasser, Ammoniak; 1:1‐Typ: Wasser, Methanol, Äthanol, Propanol‐1, Äthylenglykol, Dimethyläther, Methylamin, Äthylamin; 2:1‐Typ: Butanol‐1, Pentanol‐1, 1‐Aminopropan, 1‐Aminobutan, Äthylendiamin, 1,4‐Diaminobutan. Die Zahl der Addenden richtet sich nach der Molekülgröße und nicht nach der Zahl der polaren Gruppen. Alle Additionsverbindungen sind auch in Lösung beständig. Verbindungen des 2:1‐Types sind in bezug auf Chrom zweikernig.

Crystal structures of the methanol and hexanol adducts of tris(8-quinolinolato)manganese(III)

“…The trapping of alcohol molecules in such "cage-like" cavities no doubt accounts for the difficulty encountered in their removal from the respective adduct structures as shown by Burns et al (1971). Similar results were obtained by Umland et al (1961) and Umland and Adam (1965) for the analogous adducts of tris(8-quinolinolate)chromium(III).…”

Synthesis, structure, and spectral and electrochemical properties of chromium(iii) tris-(8-hydroxyquinolinate)

“…2), which showed an initial small weight loss around 200 °C, a second step around 470 °C, and final weight losses between 500 and 700 °C. Previous studies on Crq 3 36,46 and the corresponding cobalt(III) derivative 60 show that they tend to crystallize as alcohol adducts, with the solvent trapped in a "cage-like" cavity, and that the alcohol can be eliminated upon heating around 200 °C. From the thermogravimetric data, and C, H, N elemental analysis, we suggest that with our synthesis, the Crq 3 recrystallizes from 90% methanol-water with similarly trapped methanol molecules, and that these are lost in this first stage of heating.…”

“…For the above reasons, we have carried out a detailed structural, spectral and electrochemical study on chromium(III) 8-hydroxyquinolate (Crq 3 ). Although chromium(III) 8-hydroxyquinolate was first reported in 1938, 35 reliable results on its synthesis and characterization have been fairly sporadic, 6,[36][37][38][39][40][41][42][43][44] and it is only recently that relatively detailed structural data on this compound have been reported. 45 In part, this stems from the same kinetic inertness that makes this material interesting for device applications.…”

“…In addition, Crq 3 tends to crystallize as a solvate. 36,46 Following from our earlier studies on the water soluble derivative 8-hydroxyquinoline-5-sulfonate (8-HqS) with the trivalent cations Al(III), 47,48 we initially studied standard routes to Crq 3 synthesis by looking at the reaction of the water soluble 8-HqS with chromium(III) in aqueous solutions. However, no significant reaction was observed over several weeks, 49 in support of the kinetic inertness of the Cr(III) ion.…”

“…The important properties related with the 1 H fast relaxation of nearby nuclei of the Cr(III) complexes and their spherical symmetry may also make them good potential candidates for use as relaxation agents having potential application in magnetic resonance imaging (MRI).For the above reasons, we have carried out a detailed structural, spectral and relatively detailed structural data on this compound has been reported 45. In addition, Crq 3 tends to crystallize as a solvate 36,46. In addition, Crq 3 tends to crystallize as a solvate 36,46.…”