dilithium

Dilithium, Li2, is a strongly nucleophilic, diatomic molecule comprising two lithium atoms covalently bonded together. Li2 has been observed in the gas phase. It has a bond order of 1, an internuclear separation of 267.3 pm and a bond energy of 102 kJ/mol or 1.06 eV in each bond. The electron configuration of Li2 may be written as σ2.

Being the third-lightest stable neutral homonuclear diatomic molecule (after dihydrogen and dihelium), dilithium is an extremely important model system for studying fundamentals of physics, chemistry, and electronic structure theory.