Electronic reason for the stabilization of osmabenzyne

The electronic reason for the stabilization of osmabenzyne H]Cl2(PPh3)2 has been examined with the aid of orbital interaction analysis and density functional theory calculations. The results show that the six-membered metallacycle exhibits somewhat aromatic properties. The filled metal dx2−y2-orbital interacts with the equatorial p-orbital of the high reactive carbyne carbon (C) in a back-bonding fashion, which can deactivate the carbyne carbon. The chloride ligand trans to the carbyne carbon, which is a stronger π-donor, can enhance the d–p interaction. On the other hand, the π-donor ligand trans and cis to the carbyne carbon benefit the dxz–3π back-bonding interaction between the metal and carbon unit, hence stabilizing the osmabenzyne. And the silyl group on the carbon adjacent to the carbyne carbon can prevent the protonation back to the corresponding osmabenzene through its polarization effect in a way.