Unusual Hydrogen Bonds with a Hydride Atom in Boron Hydrides Acting as Proton Acceptor. Spectroscopic and Theoretical Studies

Abstract

The interaction of different proton donors with ionic (Bu 4 NBH 4 ) and neutral (BH 3 NEt 3, BH 3 P(OEt) 3 ) boron hydrides was studied by IR and NMR spectroscopy in solution (CH 2 Cl 2, C 6 H 14, and C 6 D 12 ). A close similarity was observed between the spectral and thermodynamic properties of these unusual BH···HX and those of classical H bonds. The typical characteristics of hydrogen bonding, such as linearity of the fragment H···HX, lengthening of X−H and H−B bonds, and strong electron redistribution, were confirmed by ab initio calculations.