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Nucleophilic or electrophilic phosphinidene complexes ML(n)=PH; what makes the difference?
Andreas W Ehlers1, Evert Jan Baerends, Koop Lammertsma
1Department of Chemistry, Faculty of Sciences, Vrije Universiteit, De Boelelaan 1083, NL-1081 HV Amsterdam, The Netherlands.
Journal of the American Chemical Society
|March 14, 2002
Summary
Density functional studies reveal that transition metal-stabilized phosphinidenes exhibit strong sigma-donor and pi-acceptor properties. Ligand choice significantly influences their chemical reactivity and bonding interactions.
Area of Science:
- Organometallic Chemistry
- Computational Chemistry
- Inorganic Chemistry
Background:
- Phosphinidene complexes are crucial intermediates in organometallic chemistry.
- Understanding their electronic structure and reactivity is key to designing new catalytic systems.
- Spectator ligands play a vital role in modulating the properties of metal-bound phosphinidenes.
Purpose of the Study:
- To investigate the equilibrium structures and bonding of phosphinidene transition metal complexes (ML(n)=PH).
- To analyze the influence of spectator ligands (L) on the electronic properties and chemical reactivity of phosphinidenes.
- To quantify the sigma- and pi-bond strengths in the metal-phosphinidene interaction.
Main Methods:
- Density functional studies employing the local density approximation with nonlocal corrections.
- Self-consistent calculations for equilibrium structures.
- Bond energy analysis (electrostatic, Pauli repulsion, orbital interaction).
- Symmetry decomposition for sigma- and pi-bond strength estimation.
Main Results:
- Spectator ligands with strong sigma-donor capabilities enhance phosphinidene nucleophilicity.
- Ligands with strong pi-acceptor capabilities stabilize the pi-orbital and increase affinity for electron-rich species.
- Phosphinidenes are found to be strong pi-acceptors and even stronger sigma-donors.
- Metal-phosphinidene interaction strength increases down the transition metal groups.
Conclusions:
- The electronic structure and reactivity of transition metal-phosphinidenes are tunable via spectator ligands.
- These complexes exhibit significant sigma-donor and pi-acceptor characteristics.
- The metal-phosphinidene bond strengthens across transition metal series, impacting their chemical behavior.
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