Oligomer clusters, hydrogen bonding

In a recent thermodynamic and spectroscopic study Redington66 -68) evaluated AH and AS for the formation of cyclic and open-chain oligomers of hydrogen fluoride. His best fit to vapor density, heat capacity, excess entropy, excess enthalpy, and infra red absorption data shows a monotonous increase in AH per hydrogen bond with increasing number of HF molecules both for open-chain and cyclic clusters, using the relation... 

Kofranek, M., Lischka, H., and Karpfen, A., Ah initio studies on hydrogen-bonded clusters. I. Linear and cyclic oligomers of hydrogen cyanide, Chem. Phys. 113, 53-64 (1987). 

Karpfen, A., and Yanovitskii, O, Cooperativity in hydrogen bonded clusters An improved ab initio SCF study on the structure and energetics of neutral, protonated and deprotonated chains of neutral, cyclic hydrogen fluoride oligomers, J. Mol. Struct. (Theochem) 314,211-227 (1994). 

To recapitulate what we have discussed so far, we emphasize that three major bonding effects underlie the interaction between the gold clusters Au3 and Au4 and water oligomers. They are the anchor Au-O bonding, the nonconventional O-H Au hydrogen bonding, and the activation of the adjacent O-H bond. We provide a computational evidence that the formation of the donor-acceptor coordinative (anchor) bond Au-O in the studied complexes is a necessary prerequisite (but not sufficient) to the formation of the nonconventional hydrogen bond and to the activation of the adjacent O-H bond, and therefore this bond dominates the interaction mechanism. 

Keywords gold, gold cluster, ammonia oligomer, anchoring bond, nonconventional hydrogen bond,... 

M. Kofranek, A. Karpfen, and H. Lischka, Chem. Phys., 113, 53 (1987). Ab Initio Studies on Hydrogen-Bonded Clusters. 1. Linear and Cyclic Oligomers of Hydrogen Cyanide. 

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