Ca-Ca interaction in inverse sandwich Ca-C8H8-Ca.

Area of Science:

• Inorganic Chemistry
• Computational Chemistry
• Quantum Chemistry

Background:

• Inverse sandwich complexes offer unique bonding perspectives.
• Calcium's electronic structure influences complex formation and stability.
• Understanding metal-ligand interactions is crucial for predicting complex behavior.

Purpose of the Study:

• To investigate the electronic states and bonding characteristics of calcium inverse sandwich complexes.
• To explore the influence of ligands, such as C8H8 and C4H4, on calcium-calcium interactions.
• To determine the stability and preferred electronic configurations of these complexes, with and without coordinating solvent molecules.

Main Methods:

• Density Functional Theory (DFT) calculations were employed.
• Electronic states (singlet, triplet) and diradical character were analyzed.
• Metal-ligand interactions and complex stability were evaluated.

Main Results:

• The bare Ca-C8H8-Ca complex is predicted to be an open-shell singlet state with diradical character.
• Coordination with dimethyl ether (DME) in (DME)3Ca-C8H8-Ca(DME)3 favors a closed-shell singlet state with direct Ca-Ca bonds.
• The Ca-C4H4-Ca complex also exhibits an open-shell singlet ground state, while its DME-coordinated counterpart, (DME)3Ca-C4H4-Ca(DME)3, favors a triplet state.

Conclusions:

• Ligand choice and coordination environment significantly alter the electronic ground state and bonding in calcium inverse sandwich complexes.
• The interplay between metal-metal bonding and metal-ligand interactions dictates the stability and electronic configuration.
• These findings provide insights into the fundamental chemistry of low-valent calcium compounds.