What is it about?

Density functional theory (DFT) calculations and natural population analysis (NPA) performed on metallocenes of Fe, Ru and Os triad reveal that the cyclo-P5 ligand introduces basicity at the metal center. All-electron calculations at the B3LYP/6-311+G* level yield NPA charges of 0.28, −0.28 and −0.91 at the iron center in [FeCp2], [FeCp(η5-P5)] and [Fe(η5-P5)2], respectively. The accumulation of negative charge at the metal center is found to be similar in the cyclo-P5 analogues of ruthenocene and osmocene. Thus, for example, the net NPA charges on Ru and Os in the decaphosphametallocenes are predicted to be −0.6 to −0.9, respectively.

Featured Image

Why is it important?

Our study reveals that there is transfer of small amount of electron density from each phosphorus atom to the metal center in the decaphospha metallocenes [M(η5-P5)2] , M=Fe, Ru, Os, leading to a significant build-up of negative charge on the metal. This is a new feature observed in the transition metals bound to cyclo-P5 ring. This finding is indeed supported by the indirect evidence observed by Scherer and co-workers from the diamagnetic behavior in an iridium derivative of Fe(P5), that the Fe atom is negatively charged while one of the P atoms is positively charged.

Perspectives

The extent of covalent bond formation between the metal and the ligand is more pronounced for the cyclo-P5 than the cyclopentadienyl ligand. Consequently, Cp retains 56−68% of aromaticity, the P5 ring exhibits 26−51% aromaticity as compared to the free anionic rings.

E.J. Padma Malar
University of Madras

Read the Original

This page is a summary of: Can the cyclo‐P5 Ligand Introduce Basicity at the Transition Metal Center in Metallocenes? A Hybrid Density Functional Study on the cyclo‐P5 Analogues of Metallocenes of Fe, Ru and Os, European Journal of Inorganic Chemistry, June 2004, Wiley,
DOI: 10.1002/ejic.200400058.
You can read the full text:

Read

Contributors

The following have contributed to this page