Chemistry of the heavy group 15 elements with the pyridyl tethered 1,2-bis(imino)acenaphthene "clamshell" ligand.

Cobaltocene has been used as a one-electron reductant in a facile route to generate pnictogen(I) (P, As) synthons. These subsequently undergo a formal 4 + 2 cycloaddition with a pyridyl tethered 1,2-bis(imino)acenaphthene "clamshell" ligand to yield N-heterocyclic chlorophosphines and -arsines, which are precursors to the corresponding N-heterocyclic pnictenium cations. In the absence of a reductant the "clamshell" ligand can be used in forming hypervalent donor-acceptor complexes with heavy main group elements (Sn, Sb and Bi).