Sequential bond energies of Pt +(NH 3) x ( x=1–4) determined by collision-induced dissociation and theory

Abstract

The sequential bond energies of Pt +(NH 3) x ( x=1–4) are determined by collision-induced dissociation (CID) with Xe using guided-ion beam tandem mass spectrometry. Analysis of the kinetic energy-dependent cross sections includes consideration of multiple ion–neutral collisions, the internal energies of the complexes, and the dissociation lifetimes. We obtain the following 0 K bond energies in eV (kJ/mol): 2.84±0.12 (274±12), 2.71±0.10 (261±10), 0.80±0.05 (77±5), and 0.48±0.04 (46±4) for (NH 3) x−1 Pt +NH 3 with x=1–4, respectively. These values are in reasonable agreement with results of density functional ab initio calculations performed here. The trend in these bond energies is compared with those of platinum carbonyl cations and nickel ammonia cation complexes and discussed in terms of sdσ-hybridization, electrostatic interactions, and ligand–ligand steric interactions.