Complexes containing odd-electron Be-Be bonds are still rare until now. Hereby, a series of neutral di-beryllium amidinate complexes containing a Be-Be bond were explored theoretically. The complexes with direct chelation with the Be2 dimer by the bidentate amidinate (AMD) ligands are always corresponding to their global minimum structures. The detailed bonding analyses reveal that the localized electrons of the Be-Be fragment can be adjusted by the amount of AMD ligands because each AMD ligand only takes one electron from the Be2 fragment. Meanwhile, the hybridization of the central Be atom also changes as the number of AMD ligands increases. In particular, the sp3 -hybridized single-electron Be-Be bond is firstly identified in the tri-AMD-ligands-chelated neutral D3h -Be2 (AMD)3 complex, which also possesses the higher stability compared to its monoanionic D3h -Be2 (AMD)3 - and monocationic C3 -Be2 (AMD)3 + analogues. Importantly, our study provides a new approach to obtain a neutral odd-electron Be-Be bond, namely by the use of radical ligands through side-on chelation.
Keywords: amidinates; beryllium−beryllium bonds; hybridization; neutral odd-electron bonds.
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