The gold-ammonia bonding patterns of neutral and charged complexes Au m 0+/-1-(NH3)n. I. Bonding and charge alternation.

The gold-ammonia bonding patterns of the complexes which are formed between the ammonia clusters (NH(3))(1< or =n< or =3) and gold clusters of different sizes that range from one gold atom to the tri-, tetra-, and 20-nanogold clusters are governed by two basic and fundamentally different ingredients: the anchoring Au-N bond and the nonconventional N-H...Au hydrogen bond. The latter resembles, by all features, a conventional hydrogen bond and is formed between a typical conventional proton donor N-H group and the gold cluster that behaves as a nonconventional proton acceptor. We provide strong computational evidence that the gold-ammonia bonding patterns exhibit distinct characteristics as the Z charge state of the gold cluster varies within Z=0,+/-1. The analysis of these bonding patterns and their effects on the N-H...N H-bonded ammonia clusters are the subject of this paper.