Revisiting sp² Dilithio Methandiides: From Geometric Curiosity to Simple Bonding Description

Area of Science:

• Organometallic Chemistry
• Computational Chemistry
• Coordination Chemistry

Background:

• The Liddle complex (1) is a reported tetracoordinate dilithio methandiide with an unusual geometry.
• Understanding the electronic and steric factors governing its structure is crucial for advancing organolithium chemistry.

Purpose of the Study:

• To investigate the coordination chemistry of the dilithio methandiide complex (1).
• To elucidate the origin of its unique geometric configuration using computational methods.
• To propose an alternative bonding description for the central methandiide carbon.

Main Methods:

• Application of diverse computational techniques.
• Analysis of non-covalent interactions (steric and electrostatic).

Main Results:

• Non-covalent interactions are identified as the primary driving force behind the complex's geometry.
• The central methandiide carbon is best described as tricoordinate and sp²-hybridized.
• Complex (1) features a single C-Li sigma bond, differentiating it from other dilithio methandiides.

Conclusions:

• The bonding in complex (1) is distinct from previous interpretations, resembling that of aryllithium compounds like phenyllithium.
• This work provides a refined understanding of bonding in low-coordinate carbon-lithium compounds.