Structural chemistry of some six coordinate seven electron pair group V complexes.

The subject of this thesis is a study of coordination complexes of the group V elements in which the central metal atom has six bonding and one non-bonding pair of valence electrons. After a short discussion of the theoretical aspects of this type of complex, a comparison with respect to structural type is presented using examples from the literature as well as those studied by the author. The structural type (based either on a pentagonal bipyramid or a trigonally distorted octahedron, both of which contain a stereochemically active non-bonding pair of electrons) is rationalised. Structural details in the form of full single crystal X-ray crystallographic investigations are presented for six tris-chelate complexes which are of the above type: Potassium trisoxalatoantimonate(III) Tris diethyldithiophosphatoarsenic(III) Tris diethyldithiocarbamatobismuth(III) Tris ethylxanthatobismuth(III) Tris methylxanthatobismuth(III) and antimony(III). In addition three further molecular structures are reported of compounds which were prepared as a result of chemical investigations on six coordinate seven electron pair complexes: Hexamminecobalt(III) nonafluoroantimonate(III) Tris(8-quinolinato)bismuth(III) hydrate Bis(diethyldithiocarbamato)antimony(III) fluoroborate The last of these has four bonding and one non-bonding pair of electrons in the valence shell and so forms an interesting comparison with the principal topic. Attempts to coordinate to the non-bonding pair of valence electrons in tris diethyldithiocarbamatoantimony(III) using Lewis acids (eg. BF3, Mo(CO)5) were unsuccessful.