A theoretical study of aromaticity in 1,2-diaza and 1,2-diphospha-cyclooctatetraenes and their role as ligands in organometallic compounds

Eight member rings with two adjacent pnicogen heteroatoms are analysed from a theoretical point of view. 1,2-diaza-cyclooctatetraene presents a distorted structure when it has a double negative or double positive charge. On the other hand, 1,2-diphospha-cyclooctatetraene is a perfect planar (presumably aromatic) structure when the global charge is −2 or +2. The capability of these rings to bond to a Cr(0) carbonyl fragment is also analysed.