Palladium(0) complexes facilitate many catalytic transformations that begin with the oxidative addition of a halobenzene. The ligation state of the palladium during this reaction is a vexing issue, owing to the inherent difficulty of isolating reactive, coordinatively unsaturated metal complexes. By isolating them in the gas phase in an ion‐trap mass spectrometer, the reactivity of mono‐ and bisligated palladium complexes can be directly compared, and the former proved to be several orders of magnitude more reactive towards halobenzenes. Calculations of barrier heights for the oxidative addition led to additional experiments, which demonstrated that although the reaction proceeded to completion for iodobenzene, the reaction was slower for bromobenzene and progressed only as far as an ion–molecule adduct for chloro‐ and fluorobenzene.

We have used molecular dynamics simulations to study the structure and nonlinear vibrational spectra of a face-wise amphipathic α-helical peptide when adsorbed onto hydrophobic, neutral, and charged hydrophilic surfaces from the solution state. Visible-infrared sum-frequency spectroscopy is a powerful probe of interfacial structure, and is unmatched in its sensitivity and specificity for molecules at the buried solid− liquid interface. However, although the resulting experimental spectra serve as fingerprints for the adsorbed-state structure, there is currently limited understanding in how to extract quantitative structural information. We compare our structural results and simulated spectroscopic response with the results of several experimental studies in the literature. We are able to reproduce all of the main features in the experimental observations, and thereby provide some additional fundamental insight into the interaction of this important class of molecules with surfaces of varying hydrophobicity and charge.