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 (Bu4NBH4) and neutral (BH3NEt3, BH3P(OEt)3) boron hydrides was studied by IR and NMR spectroscopy in solution (CH2Cl2, C6H14, and C6D12). 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.