Book of Abstracts Book of Abstracts - Universität Konstanz

46
B - 8
Triplatinum carbonyl complexes: preference for terminal sites and
chiral structures
Timo Santa-Nokki and Hannu Häkkinen
Department of Physics, Nanoscience Center, University of Jyväskylä, Finland
We present a systematic density functional theory (DFT) study on the structures of
triplatinum carbonyls Pt3(CO)x q with x=1-6 and q=0,-1. The calculations are able to fully
reproduce and explain the experimentally observed anomalous behaviour in the binding energy
of the ligands in anionic cluster carbonyls by Grushow and Ervin, 1 with the three first ligands
strongly bound (by 220-275 kJ/mol per ligand), the fourth and fifth ligand weakly bound (by
135 kJ/mol), and the sixth ligand again stronger bound (by about 200 kJ/mol). The first three
ligands bind in a tilted configuration at terminal sites in the plane of the triangular platinum
core, making the half-saturated Pt3(CO)3 - a chiral complex. We discuss the relative preference of
terminal and bridge adsorption sites for CO in Pd, Pt, and Au cluster carbonyls in terms of the
strength of the relativistic effects in the metal-carbon bond. We also discuss the implications of
the current work regarding design of bimetallic Au-Pt cluster nanocatalysts for CO oxidation. 2
Figure 1. Sequential binding energy of CO ligands to anionic platinum cluster carbonyls Pt 3(CO) x - for x=1-6. The
DFT results of this work are compared to TCID and PD data from Ref. 1. A conservative estimate for the accuracy of
the theoretical values is ±10 kJ/mol. For each x we also show the ground state structure of the anionic cluster
carbonyl.
References
[1] A. Grushow and K.M. Ervin, J. Am. Chem. Soc. 117, 11612 (1995); A. Grushow and K.M. Ervin,
J. Chem. Phys. 106, 9580 (1997); K.M. Ervin, Int. Reviews in Physical Chemistry 20, 127 (2001).
[2] T. Santa-Nokki and H. Häkkinen, submitted.