Prediction and characterization of the single-electron sodium bond complexes Y-C...Na-H [Y = H3, H3CH2, (H3C)2H and (H3C)3].

The prediction and characterization of the single-electron sodium bond complexes Y-C...Na-H [Y = H(3), H(3)CH(2), (H(3)C)(2)H and (H(3)C)(3)] have been investigated for the first time by using MP2/6-311++G(d,p), MP2/6-311++G(2d,2p) and MP2/aug-cc-pVDZ methods. The strength of the interactions in H(3)C...Na-H, H(3)CH(2)C...Na-H, (H(3)C)(2)HC...Na-H, and (H(3)C)(3)C...Na-H complexes has been analyzed. It is shown that the (H(3)C)(3)C radical with Na-H forms the strongest single-electron sodium bond, followed by the (H(3)C)(2)HC radical and then the H(3)CH(2)C radical. H(3)C radical forms the weakest single-electron sodium bond. NBO and AIM analyses have also been used to estimate such conclusions. Furthermore, there are few linear/nonlinear relationships among the several parameters in system and the interaction mode of single-electron Na bond is LP(1)(C) --> LP(1)*(Na), which is different from the single-electron H bond and single electron halogen bond. By comparisons with some related systems, it is concluded that the strength of single-electron bond is increased in the order: hydrogen bond < sodium bond < bromine bond < lithium bond.