STUDY OF MULTIMETALLIC GERMANIUM AND TIN COMPOUNDS IN THEIR LOW OXIDATION STATE

Abstract

Carbenes have been explored in various applicatory fields such as organocatalysts, as components of FLPs (Frustrated Lewis Acid-Base Pair), in metallopharmaceuticals, homogeneous catalysis, activation of small molecules, organometallic materials and so on. Following the same trend heavier analogues of silicon, germanium and tin have been synthesized over the last few decades and have been utilized as FLPs, as ligands to transition metals, in catalysis and small molecule activation. Furthermore, the bistetrylenes have been explored to study the cooperative effect of two terylenes in the same molecular framework and they have been found to be very useful in small molecule activation, catalysis, and coordination with main group as well as transition metals. To further explore such cooperative properties, we have synthesized various multi metallic systems with different oxidation states. The first chapter explores the synthesis and characterization of bis(chlorogermyliumylidene) in a 2N2P ligand system where it is found to be unstable at room temperature in the presence of base and hence rearranged products are identified and characterized. So, the ligand is converted to its saturated counterparts and further used in synthesis of new bis(chlorogermyliumylidene)s which were found to be stable at room temperature. On addition of bases like DMAP (4-dimethylaminopyridine) and PMe3, the complexes coordinated with them and the reactions were studied using NMR techniques. The second chapter explores the synthesis of Au(I)-Au(I) aurophilic complex. On reaction of the previous ligand system with Gold(I) chloride in one and two equivalents, monometallic and bimetallic complexes are synthesized respectively. The monometallic gold complex was reacted with GeCl2.Dioxane in the anticipation of formation of Z-Ligand like system. However, the germanium center was found to undergo an addition reaction with the gold chloride bond rather than coordinating with the ligand. So, the monometallic gold complex was reacted with PPh2Li followed by GeCl2.Dioxane to form the targeted aurophilic complex. The third chapter explores the synthesis, characterization, and computational study of multimetallic tin complexes. On reaction of N-(2,6-diisopropylphenyl)imidazole with Bis[bis(trimethylsilylamino)] tin(II) as a base, a dimeric tin complex was formed. Further, Bis[bis(trimethylsilylamino)] tin(II) was reacted with bis(imidazolyl)methane to form a crown shaped tetrametallic tin complex. Both the complexes were characterized by SCXRD and NMR techniques. Computational study of the tetrametallic complex showed the presence of electron density at the center of the ring with the two of tin centers being stannides and the other two centers being stannyliumylidenes.