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In this paper, empirical corrections for anharmonic ground-state vibrations of hydrogen and deuterium in the hydrogen bridges A–L· · ·B, L ¼ H, D are introduced into the geometric hydrogen bond correlation analysis based on the empirical Pauling valence bond orders. The method is verified using the examples of the hydrogen bonded anions in [(CO)5Cr–CxN· · ·H· · ·NxC–Cr(CO)5]2 As(Ph)4 þ (1h), in [(CO)5Cr–CxN· · ·H· · ·NxC–Cr(CO)5]2 N(n-propyl)4 þ (2h), in the model system [CxN· · ·H· · ·NxC]2 Liþ (3h), and their deuterated isotopologs (1d, 2d and 3d) studied previously by dipolar NMR and theoretical methods by H. Benedict et al. [J. Am. Chem. Soc. 120 (1998) 2939]. The new corrections are able to describe isotope effects on hydrogen bond geometries from the weak to the strong hydrogen bond regime, taking into account single and double-well situations. q 2004 Elsevier B.V. All rights reserved