Prediction and characterization of the HMgH•••LiX (X = H, OH, F, CCH, CN, and NC) complexes: a lithium-hydride lithium bond

In the present paper, a new type of lithium bonding complex HMgH center dot center dot center dot LiX (X = H, OH, F, CCH, CN, and NC) has been predicted and characterized. Their geometries (C-infinity nu) with all real harmonic vibrational frequencies were obtained using the second-order Moller-Plesset perturbation theory (MP2) with 6-311 + + G(d, p) basis set. For each HMgH center dot center dot center dot LiX complex, a lithium bond is formed between the negatively charged H atom of an HMgH molecule and the positively charged Li atom of an LiX molecule. Due to the formation of the complexes, the Mg-H and Li-H bonds are elongated. Interestingly, the Li-X harmonic vibrational stretching frequency is blueshifted in the HMgH center dot center dot center dot LiX (Y = CCH, CN, and NC) complexes and redshifted in the HMgH center dot center dot center dot LiX (X = H, OH, and F) complexes. The binding energy of this type of lithium bond ranges from 12.18 to 15.96 kcal mol(-1), depending on the chemical environment of the lithium. The nature of lithium-hydride lithium bond has also been analyzed with natural bond orbital (NBO) and atoms in molecules (AIM).