Pentacoordinated and hexacoordinated compounds
This chapter covers recent advances in the title area published during 2018. As in previous years the chemistry of pentacoordinated phosphorus compounds has been divided into two main subsections including aspects of synthesis, structure and reactivity of the above-mentioned compounds as well as participation as intermediates or transition states. In this respect, synthetic strategy for novel metallophosphoranes, reactivity of selected spirophosphoranes and fluorinated phosphoranes have been described. Moreover, the fragmentation pathways of aryloxy spirophosphoranes have also been proposed. In turn, the involvement of pentacoordinated intermediates or transition states in phosphine-mediated reactions as well as in phosphodiester cleavage have been reviewed. For oligomerization processes of isocyanates, monosaccharides and polymerization of cyclic ethylene phosphate the importance of pentacoordinated species as a driving force for these processes has been explained and confirmed.Finally, the development of the chemistry of hexacoordinated compounds has been mainly limited to the synthesis and application of novel salts bearing hexacoordinate phosphate anion. Nevertheless, a report on the preparation of neutral hexacoordinate phosphorus–ruthenium complex has also appeared.