A Stacking Interaction between a Bridging Hydrogen Atom and Aromatic π Density in the n‐B₁₈H₂₂–Benzene System

Abstract

The structures of n-B18H22 and of n-B18H22 x C6H6 were determined by single-crystal X-ray analysis at -60 degrees C. The geometry of the boron cluster itself does not seem to be appreciably affected by solvation. There does, however, appear to be an unusual interaction of a polyborane bridging hydrogen atom with the benzene pi system, giving rise to an extended stacked structure. The 1H{11B} spectrum of n-B18H22 in [D6]benzene differs from that in [D12]cyclohexane most noticeably in the bridging proton region. Upon moving from the aliphatic to the aromatic solvent, the greatest increase in shielding was for the signal corresponding to the bridge hydrogen atom that interacts with the pi system of benzene; the signal was shifted upfield by 0.49 ppm. Density functional theory calculations were performed on 1:1 and 2:1 complexes of the n-B18H22 unit with benzene.

Nonclassical B‐Hb⋯π interaction in diborane⋯localized‐π sandwiches: A DFT‐D3 study

“…Depending on the nature of π‐systems, H b ⋯X bond distances (distance measured between H b and the geometric mean of the π bond) vary within the range 2.55‐3.03 Å (Table ). In case of half sandwiches, the H b ⋯X distances in B 2 H 6 ‐O 2 , B 2 H 6 ‐C 2 H 4 , and B 2 H 6 ‐C 2 H 2 complexes are 2.55, 2.88, and 2.86 Å respectively, although slightly shorter distances (~2.50 Å) for the interaction of DB with arenes are reported in literatures . Recently, H b ⋯X bond distances of 2.37‐2.58 Å are also reported for boranes adsorbed on the surface of undoped/doped graphene model systems .…”

“…On the other hand, in nonconventional hydrogen bonding, donor and/or acceptor atoms are less electronegative that is, formed between weak donors like CH, and/or weak acceptor like π‐electrons . Recently, B‐H b ⋯π interaction has been established experimentally in the X‐ray crystal of B 18 H 22 ⋯C 6 H 6 . Moreover, presence of such non‐conventional hydrogen bonding has also been reported in between boron cluster and phenyl ring in Ir‐dithiolene‐phosphine complex .…”

Structure and decomposition of [HFe(CO)4(B2H5)], a revised behavior of an old uncharacterized complex

“…1, Scheme 1). A similar example was reported recently in a (B 2 H 6 )-benzene study [59] wherein the benzeneediborane system was taken as a model to describe the nature of the observed interaction between an n-B 18 H 22 cluster and benzene molecule [60]. Using the appropriate treatment at different levels of computational theory, this interaction has been found to be mostly dispersive with a stabilizing energy of 3.7 kcal/mol [58].…”

Inorganic Chemistry: Shore and Angelici Awarded / Biomaterials: Langer Honored

“…Shore's research interests include clusters and other arrays of transition metals and the rare earths, metallocene complexes for catalysis, and polyhedral borane derivatives. He recently described a stacking interaction in a B 18 H 22 –benzene system between a bridging hydrogen atom and π density in Chemistry – A European Journal 2a and previously described an inclusion complex with [Gd(dmf) 8 ] 3+ ions encapsulated in pockets of an anionic array of {[Cu 6 (CN) 9 ] 3− } ∞ units in Angewandte Chemie 2b…”