Change of coordination from tetrahedral gold-ammonium to square-pyramidal gold-arsonium cations

E. Zeller, H. Beruda, A. Kolb, P. Bissinger, J. Riede, H. Schmidbaur

Research output: Contribution to journalArticlepeer-review

128 Scopus citations


RECENT work1-5 has shown that gold-based ligands in compounds of carbon and nitrogen can induce novel molecular structures with coordination numbers at C and N as high as 5 and 6. These phenomena must be ascribed to metal-metal interactions (Au...Au), which can overrule bonding in classical configurations. Here we describe a study of the molecular structures of tetra(auro)ammonium ((LAu)4N+) and tetra(auro)arsonium ((LAu)4As+) cations (where L is a ligand). We find that the classical tetrahedral structure in these four-coordinate compounds is abandoned in favour of a square-pyramidal geometry once the radius of the central element is too large to allow for metal-metal bonding in a tetrahedral geometry. Thus, whereas the nitrogen compounds adopt a tetrahedral structure, for the larger arsenic atom an arsenic-capped square of gold atoms represents a more favourable core geometry. We have not yet been able to prepare the intermediate phosphorus compound, but we expect it also to have the square-pyramidal structure.

Original languageEnglish
Pages (from-to)141-143
Number of pages3
Issue number6331
StatePublished - 1991
Externally publishedYes


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