Modellsysteme für die Gallium-Extraktion, II / Model Systems for Gallium Extraction, II

Abstract

The introduction of a methyl substituent in the 2-position of 8-oxy-quinoline strongly alters its ligand properties in the complex formation with gallium(III). From aqueous solutions (ammonium acetate buffer, acetic acid, gallium nitrate) a pale-green complex (2-MeOx)2GaOAc is precipitated instead of the tris(oxinate) chelate. According to a single crystal X-ray diffraction study, the gallium atom is pentacoordinate in this complex, with two chelating 2-MeOx and one monocoordinate acetate ligands. Similar acetato complexes were generated with equally hindered 2,4-dimethyl- and 2,5,7-trimethylquinoline, as well as with 2-ethyl- and 2-n-propylquinoline ligands. Retaining the 2-MeOx ligand, acetate OAc could be exchanged for trifluoroacetate, propionate, cyanoacetate, and (in binuclear complexes) equivalents of succinic, maleic, fumaric, and acetylenedicarboxylic acid. From this series, crystal and molecular structures have also been determined for (2-MeOx)2GaOC(O)CH2CN and [(2-MeOx)2GaOC(O)CHJ2]2 (with crystal nitrobenzene). In the cyanoacetate, the nitrile function is not involved in intra/intermolecular metal coordination. In the binuclear succinate the molecule has a crystallographical center of inversion. As in the cyanoacetate, the environment of the two equivalent gallium centers of the succinate is very similar to that of the acetate complex.

Electronic and magnetic properties of the interface between metal-quinoline molecules and cobalt

“…Alq 3 (99.995% pure) was purchased from Sigma Aldrich. Gaq 3 and Inq 3 were synthesized using a published method [28,29]. All three Mq 3 were purified using train sublimation, resulting in a polycrystalline powder.…”

Electronic structure of tris(8-hydroxyquinoline) aluminum thin films in the pristine and reduced states

“…4 are presented for the meridianal isomer, which has the lowest ground-state energy; 33 this is the only isomer that has been observed in the crystalline state. 36,37 As shown in Fig. 4, Alq 3 is an organometallic complex in which the metal atom has a distorted octahedral coordination; in the meridianal isomer, only one oxygen has a nitrogen atom located at the opposite position, in contrast to the facial Alq 3 geometrical isomer ͑illustrated in Fig.…”

Importance of Spin-Orbit Interaction for the Electron Spin Relaxation in Organic Semiconductors

“…Alq 3 (99.995% pure) was purchased from Sigma Aldrich. Gaq 3 , Inq 3 , and Biq 3 were synthesized using a published method [35,36]. Alq 3 , Gaq 3 and Inq 3 were purified using train sublimation, resulting in a polycrystalline powder.…”