Chelate Ligands for the Stabilisation of Low-Valent Main Group Compounds

Chelatliganden zur Stabilisierung von Niedervalenten Hauptgruppenverbindungen

by Johannes Kretsch
Doctoral thesis
Date of Examination:2021-08-25
Date of issue:2021-09-28
Advisor:Prof. Dr. Dietmar Stalke
Referee:Prof. Dr. Franc Meyer
Referee:Prof. Dr. Manuel Alcarazo
Referee:Prof. Dr. Ricardo Mata
Referee:Dr. Matthias Otte
Referee:Prof. Dr. Johannes C. L. Walker
Persistent Address: http://dx.doi.org/10.53846/goediss-8828

 

 

Files in this item

Name:Dissertation.pdf
Size:58.7Mb
Format:PDF
Description:Dissertation

The following license files are associated with this item:

Abstract

English

Reviewing the achievements in Group 13 metal complexes over the last decades, the main area of research is emerging to the development and utilisation of low-valent aluminium compounds and their heavier homologues. This work essentially focuses on synthesising low-valent group 13 complexes based on bis(benzoxazol-2-yl)methane derivates. Starting from the unsubstituted bis(benzoxazol-2-yl)methane and the bis(4-methyl-benzoxazol-2-yl)methane ligands, alkali metal precursor complexes were synthesised by concerted deprotonation-metalation reaction with corresponding metal-organic reagents. Heavier low-oxidation state group 13 metallacycles comprising bis(4-methyl-benzoxazol-2-yl)methanide were accessible by salt elimination reaction with metal(I) salts. Furthermore, aluminium(III) hydride or halide species were isolated and reduced to dimeric aluminium(II) bis(4-methyl-benzoxazol-2-yl)methanide compounds. It could be shown that the planar bis(4-methyl-benzoxazol-2-yl)methanide forms dimeric or trimeric trial metal compounds caused by its less steric hindrance in the third dimension. Therefore, bulkier bis(4-benzhydryl-benzoxzol-2-yl)methane was synthesised starting with 2-ansidine. With this ligand in hand, monomeric M(I) compounds (M(I) = Ga, In, Tl) were obtained by salt elimination reaction of alkali metal bis(4-methyl-benzoxazol-2-yl)methanide and triel(I) salts. Additionally, aluminium(III) complexes synthesised, and first reduction attempts were carried out to obtain an Al(I) compound. The trifold deprotonation of bis(4-benzhydryl-benzoxzol-2-yl)methane was accomplished by KH/18-crown-6 or a Schlosser base. These trianionic species were reacted with group 13 metall(III) halides, however, only for indium(III) a square-pyramidal complex could be observed. All obtained compounds were thoroughly investigated (e.g. Single crystal XRD, NMR, MS, EA) all by differing analytical methods.
Keywords: Bis(benzoxazol-2-yl)methane derivatives; Low-valent main group compounds; Group 13 metal coordination; Metal organic chemistry; Aluminium complexes; Structure analysis
 
Statistik