Synthesis, reactions and redox properties of 1,4-dihydro-1,4-diphosphinines and related P/Si- and P/Ge-compounds

Abstract

This Ph.D. thesis describes the P-centered as well as other heteroatom-centered reactions of mixed-atom heterocyclic compounds. <br> Initially, the synthesis of the anionic imidazole-2-thione-fused 1,4-dihydro-1,4-diphosphinines from 1,4-diphosphinine and the methylation reactions targeting the anionic P-centers to form the methylated products were explored. In addition, their P-centered redox process was investigated in detail via Cyclic Voltammetry experiments and theoretical calculations. Secondly, novel tricyclic 1,4-dihydro-1,4-phosphasiline and -1,4-phosphagermine derivatives were synthetically targeted by the backbone lithiation of 4-bis(diorganoamino)silanyl-and 4- bis(diorgano-amino)germanyl-substituted imidazole-2-thiones. P-centered redox processes of 1,4-dihydro-1,4-phosphasiline derivatives were investigated via Cyclic Voltammetry experiments and theoretical calculations. The conversion of the anionic imidazole-2-thione-fused 1,4-dihydro-1,4-phosphasilines into its Si(NR₂)₂ derivative by the addition of triphenylmethyl chloride and, subsequently, into its SiCl₂-containing derivative by the addition of an HCl ether solution was also investigated. The latter was further derivatized on the Si-center by the addition of methyllithium and methanol. The SiCl₂-containing derivative was further subjected to reduction reactions involving the Si-center and the trapping reactions of the transient silylene species with 1,3- butadiene were also investigated. Finally, the synthesis of the 1,4,4’-trichloro substituted 1,4-dihydro-1,4-phosphasiline was discussed. It was subjected to reduction reactions to synthesize the first example of an aromatic 1,4-phosphasiline derivative which led to limited success as the final product could not be isolated.