| Although the chemistry of the Group 15 elements has been fairly underdeveloped compared to that of carbon, there exists an ever-expanding range of applications for compounds containing the pnictogen elements. Pnictogen research has provided, for example, great insight into pharmaceuticals, semiconductors, and polymers, but more fundamental chemistry is required as these areas continue to grow in complexity. To serve this need, this work has as its main focus the exploration into new aspects of low-coordinated compounds of the Group 15 elements. An emphasis is placed on discovering in which ways homo- and heteroatomic P-P and P-N four-membered ring systems can be modified. It was of interest to introduce new functionalities which give the possibility of ligand displacement reactions in order to investigate how these rings can be dissociated and, hence, serve as building blocks.;For phosphazanes, these can be modified in a way to obtain bifunctional Lewis acids depending on the ligand applied. The resulting cations represent an unusual cationic N2P2 framework and highlight the potential for electron-rich centres to behave as Lewis acids despite the presence of a lone pair of electrons at the acceptor site. Donoracceptor complexes were found to either retain the N2P2 framework or to display a [3 + 1] dissociation pathway, contradicting previously reported mechanisms.;Compounds have been characterized by use of multinuclear NMR, including simulations of their often complex 31P{1H} NMR spectra, and solid state structures have been obtained in most cases. These new cations provide insight into the development of extended systems toward cationic polymers, thereby, contributing to the fundamental knowledge of inorganic chemistry.;Synthetic methods have been developed for the preparation of a number of new mono- and dicationic cyclo-phosphines and cyclo-phosphadiazanes. Selective Cl+-transfer to cyclo-phosphines results in both mono- and dications. Ligand displacement demonstrates the coordinative nature of the phosphine-phosphonium bonds and indicates the diphosphenium cation acceptor ability of these dications. |
