The ab initio calculations at the MP2/aug-cc-pvdz computational level were used to analyze the interactions of FCN, ClCN, BrCN, CF3H, CF3Cl, CH3OH, HF, HCl, HCN, SH2, SHF, SF2,H2O, HOCl, HOBr, CO, N2, and H2 molecules with BH4 1−.OnBH4 1−, three sites were accessible for interactions with L molecules to form BH4(L)1− aggregates. The faces, edges, and vertices of BH4 1− as electron donors, could interact with electron acceptor species. In addition, the BH4 1− anion, through its s-holes, could obtain electrons from interacting molecules. The significant preference of some molecules was interaction along the triangular faces, BH4(L)f 1− (where L = ClCN, BrCN, FCN, CF3Cl, CF3H) whereas, for others, the vertices, BH4(L)v 1− (where L = HOCl, HOBr, PF3) or edges, BH4(L)e 1− (where L = H2O, HF, HCl) of BH4 1− might be more suitable for interaction. Some molecules, such as CH4 and H2, despite their preferred facial interactions, could interplay with the vertex counterpart through an edge intermediate. It seems that accepting electrons (triel bonding) by BH4 1− s-holes had important roles in the face interactions for BH4(L)f 1− adducts. Bader's Quantum Theory of Atoms in Molecules (QTAIM) and Natural Bond Orbital (NBO) calculations were used to analyze optimized complexes. Noncovalent interaction (NCI) analysis was used for further determination of interactions in BH4(L)1− adducts
