RELATIONSHIP BETWEEN THE BOND LENGTHS IN NH…N, OH…O, FH…F, AND ClH…Cl HYDROGEN BRIDGES
E. G. Tarakanova, G. V. Yukhnevich
Keywords: hydrogen bridge, Hbond length, quantumchemical calculation
Pages: 10631069
Abstract
The applicability of the equation e^{((r1r0)/b)5/3} + e^{((r2r0)/b)5/3} = 1 has been studied. The equation defines the relationship between the experimental values of the covalent (r_{1}) and hydrogen (r_{2}) bond lengths in OH…O bridges for describing the relation between the experimental interatomic distances in NH…N bridges and the parameters of XH…X fragments (X = O, N, F, Cl) calculated by the density functional method (B3LYP/631++G(d,p)) for neutral, positive, and negative molecular complexes. Here r_{0} is the mean value of the XH bond length in free molecules; r_{sym} is the X…H distance in the symmetrical bridge; and b is the coefficient defined by the equation b = (r_{sym}  r_{0})/(ln2)^{3/5}. This equation allows us to adequately describe the relationships between bond lengths in nearly linear hydrogen bridges formed by oxygen, nitrogen, fluorine, and chlorine atoms. It is thus universal and can be used in studies of a wide range of substances.
