Synthesis, Molecular Structure and DFT Study of [(dpp-bian)Ga-M(Et2O)3] (M = Li, Na; dpp-bian=1,2-bis[(2,6-diisopropylphenyl)imino]acenaphthene)

The synthesis and crystal structure of the Ga-Ga bonded compound [(dpp-bian)Ga-Ga(dpp-bian)], containing the diimine ligand in its dianionic form, was evaluated by DFT studies. The studies show that the orbitals HOMO-1 (π) and HOMO-17 (σ) are responsible for the metal-metal bonding, and the LUMO (π) orbital shows bonding character with respect to the Ga-Ga bond. The gallium atoms are coordinated in a distorted trigonal-planar geometry and the ligand arrangement around the respective alkali metal atoms corresponds to a distorted tertahedron. The Ga-N distances is found to be longer , which reflects the difference in the formal oxidation state of Ga atoms. The results also show that the Ga-Li bond arises from the donation of the electron lone pair of Ga to the vacant 2s orbital of the lithium cation.