RELATIVISTIC DENSITY-FUNCTIONAL STUDIES OF NAKED AND LIGATED GOLD CLUSTERS

Electronic structure investigations on a broad range of gold compounds , including naked and ligated gold clusters, are reviewed. The calcula tions have been carried out with a recently introduced relativistic va riant of the linear combination of Gaussian-type orbitals density-func tional (LCGTO-DF) method which affords all-electron investigations for very large systems. The accuracy of the method will be evaluated for the gold dimer. Then the electronic structure of the naked cluster AU( 55) is studied, both in I-h and O-h symmetry. Nonrelativistic and rela tivistic results obtained by the present method are compared to those of the much simpler jellium model. Since triphenylphosphine is among t he most common ligands in gold chemistry a series of mononuclear gold phosphine compounds MeAuPR(3) with increasingly complex ligands PR(3) (R = H, CH3, C5H6) is discussed. The calculations reveal the success a nd the limitations of simpler phosphines often employed as model ligan ds in theoretical studies. Some aspects of the phosphine gold interact ion in these simpler compounds carry over to the main group element ce ntered gold clusters. Thereby one arrives at a rationalization of the particularly high stability of the carbon-centered octahedral cluster cation [(R,PAu)(6)C](2+) as compared to the neighboring isoelectronic boron and nitrogen-centered clusters. (C) 1994 John Wiley & Sons, Inc.