Date of Award
Dissertation - Restricted
Doctor of Philosophy (PhD)
The synthesis and coordination chemistry of new classes of scorpionate ligands are discussed, with the goal to discern the impact of steric and electronic modulation on the coordination chemistry and properties of metal scorpionates. The scorpionate ligands were functionalized by adding bulkier alkyl substituents at selected positions of the heterocycles rings, substituting pyrazoles with other heterocycles or by replacing hydrogen at the back position of boron with aromatic groups in tris(pyrazolyl)borates.
The synthesis, structures and the coordination chemistry of a series of iron (II) and iron (III) scorpionates based on third generation para-trimethylsilylphenyltris(pyrazolyl)borates, [p-Me3 SiC6 H4 B(pzx ) 3 ] are presented. The influence of pyrazolyl substituents on the spin state of iron (II) and iron (III) complexes was observed. The donor-acceptor chemistry of para-trimethylsilylphenyltris(pyrazolyl)borates in an electrochromic device will be described. The pi-stacking interactions in Fe[tBu 5 HBCB( pz )3 ]2 , with hexa-peri-hexabenzocoronenes (HBCs) tethered at the back of boron, were responsible for the unique spin characteristics of Fe[tBu5 HBCB(pz )3 ]2 .
The supramolecular structures of alkali metal salts of the Janus scorpionate [HB(mtda )3 ]- with both hard nitrogen and soft sulfur donors are described. In addition, the Janus scorpionate ligand exhibits extraordinary coordination capacity and versatility binding from two to five metal cations as demonstrated by its thallium (I) salt. The second generation Janus scorpionate ligand [HB( mtdaMe ) 3 ] have been prepared and the effect of methyl substitution versus the unsubstituted first generation Janus scorpionate on the spin state of iron (II) complexes has been studied structurally by Mossbauer spectroscopy.
We synthesized the tris(thioimiadzolyl)methane; HC(tim R )3 [where tim is thioimiadzolyl group and R = Me, tBu] to explore their coordination chemistry. The Lewis acid catalyzed thiol (CS-tim ) to thione (CN-tim ) isomerizations will be explained. Silver (I) complexes of tripodal tim ligands have been prepared; their solid state and solution properties have been investigated by spectroscopic methods.
Owing to the multinucleating capability of new tetrakis(pyrazolyl)lutidine (pz4 lut ) ligands, bimetallic silver (I) complexes with ligand binding in a bridging mode were synthesized. The synthesis and characterization of manganese (I) and manganese (II) complexes with different coordination modes was successfully achieved. Finally, a brief introduction to bridged ligand systems with a potential for synthesis of bimetallic complexes will be discussed.