(6) A; bend-back angles 31.8 (5)'(on C') and 41.3 (5)'(on C2). The electron density of the complexed acetylene carbon atoms is influenced also by the properties of phosphine ligands on the transition metal. Donor phosphine ligands like PCy, caused an increase, while acceptor ones like P (Oo-Tol), caused a decrease in polarization between the two C atoms of the metallacycle.
