Designing New Heterometallic [2 x 2] Grids using Pyrazolate-bridged Ligands

by Joanne Wong
Doctoral thesis
Date of Examination:2019-10-24
Date of issue:2020-02-18
Advisor:Prof. Dr. Franc Meyer
Referee:Prof. Dr. Franc Meyer
Referee:Prof. Dr. Sven Schneider
Referee:Prof. Dr. Dirk Schwarzer
Persistent Address: http://dx.doi.org/10.53846/goediss-7864

 

 

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Abstract

English

This dissertation focusses on designing new heterometallic [2 x 2] grids based on pyrazolate-bridged ligands exhibiting interesting magnetic and redox properties. To date, numerous homometallic metallogrids have been synthesized displaying remarkable chemical and physical properties, however, heterometallic systems consisting of two metal ions hold potential for multiple stable redox states as well as site-specific responses in the presence of an external stimulus such as light irradiation. Although heterometallic grids are synthetically more challenging due to the potential for scrambling of the metal ions, several methods have been developed to isolate specific isomers. Following a step-wise method, we have developed two new heterometallic [LH4Ru2Co2][BF4]4 and [LH4Ru2Fe2][BF4]4 grids with the anti-configuration, in which the former displayed single molecule magnetic properties typically not observed with 3d-transition metal [2 x 2] grid-like arrays. Furthermore, two new ligands were developed involving the addition of NMe moieties between the bipyridine units and a hybrid system in which the former afforded a dinuclear Fe2 complex, while the hybrid ligand system afforded homonuclear Fe4 grids. The synthesis along with the chemical and physical properties of these new molecules will be discussed.
Keywords: [2 x 2] grids; heterometallic grids; single molecule magnet; Mӧssbauer spectroscopy; pyrazole
 
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