The chemistry of penta- and hexacoordinated compounds continues to expand in its breadth and application. In this context the chemoselective synthesis of novel 1,3,2λ⁵-benzodioxaphospholes as well as N–H cleavage of selected amines by tricoordinate phosphorus compounds furnishing pentacoordinated adducts have been described. Pentacoordinated phosphoranes have been also postulated as intermediates or transition states in various chemical and biochemical processes such as nucleophilic substitution at phosphonium centres, aminolysis of 2,4-dinitrophenyl ethyl phosphate promoted by methylamine or transfer of a phosphorus atom or DNA cleavage by bacteriophage λ exonuclease. Moreover studies on addition of diverse O–H and N–H-containing compounds to geometrically constrained phosphorus triamides have been reported. The development of the chemistry of hexacoordinated phosphorus compounds has been mostly limited to preparation of diverse perfluoroalkyl fluorophosphates as well as to definition of their role in the synthesis of selected phosphabut-1-enes.