Non-Covalent Interactions in Hydrogen Storage Materials LiN(CH3)2BH3 and KN(CH3)2BH3

Abstract

Abstract:In the present work, an in-depth, qualitative and quantitative description of non-covalent interactions in the hydrogen storage materials LiN(CH 3 ) 2 BH 3 and KN(CH 3 ) 2 BH 3 was performed by means of the charge and energy decomposition method (ETS-NOCV) as well as the Interacting Quantum Atoms (IQA) approach. It was determined that both crystals are stabilized by electrostatically dominated intra-and intermolecular M¨¨¨H-B interactions (M = Li, K). For LiN(CH 3 ) 2 BH 3 the intramolecular charge transfer appeared (B-HÑLi) to be more pronounced compared with the corresponding intermolecular contribution. We clarified for the first time, based on the ETS-NOCV and IQA methods, that homopolar BH¨¨¨HB interactions in LiN(CH 3 ) 2 BH 3 can be considered as destabilizing (due to the dominance of repulsion caused by negatively charged borane units), despite the fact that some charge delocalization within BH¨¨¨HB contacts is enforced (which explains H¨¨¨H bond critical points found from the QTAIM method). Interestingly, quite similar (to BH¨¨¨HB) intermolecular homopolar dihydrogen bonds CH¨¨¨HC appared to significantly stabilize both crystals-the ETS-NOCV scheme allowed us to conclude that CH¨¨¨HC interactions are dispersion dominated, however, the electrostatic and σ/σ*(C-H) charge transfer contributions are also important. These interactions appeared to be more pronounced in KN(CH 3 ) 2 BH 3 compared with LiN(CH 3 ) 2 BH 3 .

On the Stability of Cis‐ and Trans‐2‐Butene Isomers. An Insight Based on the FAMSEC, IQA, and ETS‐NOCV Schemes

“…In turn, Bader criticized [7c] the energy decomposition scheme that has been applied by Bickelhaupt et al Further in depth studies by means of the interacting quantum atoms (IQA) scheme as well as by the FAMSEC method [7e] consistently point at stabilizing intra‐molecular CH•••HC interactions in the planar biphenyl and its higher energy as compared with the twisted trans ‐isomer shall be attributed to the destabilization of the carbon atoms and particularly those of the bay. It shall be referenced that the similar debates are observed when considering homopolar BH•••HB interactions in hydrogen storage materials . For example, we have recently reported, in contradiction to the series of the cutting‐edge articles by McGrady et al, [5,11c,d] that the homopolar BH•••HB interactions in LiNMe 2 BH 3 are destabilizing; interestingly, the inter‐molecular homopolar CH•••HC interactions in LiNMe 2 BH 3 appeared to be stabilizing …”

Intermolecular interactions in group 14 hydrides: Beyond CH···HC contacts

“…For the interaction topology we use a notation based on the number of EAH groups at each side of the interacting unit, for example, 1:1 involves two vertices, 4:4 two square faces, and so forth. The 1:1 and 3:3 interaction topologies have been studied for all polyhedral molecules E n H n (E 5 C, Si, Ge; n 5 4, 8,20), in line with our previous work on polyhedranes. [9] Furthermore, we have included the 1:3 topology for tetrahedranes and the 4:4 one for cubanes.…”

“…The additive character of theses interactions has been observed, for instance, in the spatial arrangement of “molecular ladders.” In another interesting work, the stabilization of a pseudotetrahedral Ni II complex was achieved via attractive CH···HC interactions . Recently, the importance of CH···HC contacts in the crystalline phases of several hydrogen storage materials has been pointed out …”

“…[19] Recently, the importance of CHÁÁÁHC contacts in the crystalline phases of several hydrogen storage materials has been pointed out. [20] According to the peculiar features of the hydrogen atom that allow it to establish a wide diversity of intermolecular interactions, homonuclear dihydrogen contacts involving other interacting units beyond carbon can be expected. Recently, attractive intermolecular interactions involving NAHÁÁÁHAN and BAHÁÁÁHAB contacts have been identified in two salts of amidoborane A(BH 3 NH 2 ), with A 5 Li, Na.…”

Boron-Based (Nano-)Materials: Fundamentals and Applications

“…Other candidates for chemical hydrogen storage are boranes, the simplest candidate being ammonia borane (NH3BH3). Sagan et al [9], for their part, considered derivatives with the following molecular structures: LiN(CH3)2BH3 and KN(CH3)2BH3.…”