Theoretical prediction and the characters of a new type of weak interaction: A single-electron sodium bond system with H–Be as an electron donor and Na–Y (Y = H, OH, F, CCH, CN and NC) as electron acceptors

A new single-electron sodium bond system with H–Be as an electron donor (sodium acceptor) and Na–Y (Y = H, OH, F, CCH, CN and NC) as electron acceptors (sodium donors) has been proved by using theoretical calculated methods at MP2/6-311++G(d,p) and MP2/aug-cc-pVDZ level firstly. The results of calculations show that the binding energies for the analyzed complexes are in the range of −15.23 to −19.24 kJ mol−1 at the CCSD(T)/aug-cc-pVDZ level, with the sequence of HBe⋯Na–H(I) → HBe⋯Na–OH(II) → HBe⋯Na–F(III) → HBe⋯Na–CCH(IV) → HBe⋯Na–CN(V) → HBe⋯Na–CN(VI), the interaction strengths of complexes are increasing and the intermolecular distance dBe⋯Na, stretching frequencies of Na–Y bond decreased. Hence, they may be classified as red-shifting single-electron sodium bonds.