The Direct Mechanocatalytic Suzuki-Miyaura Reaction of Small Organic Molecules.

The molecular Suzuki cross-coupling reaction was conducted mechanochemically, without solvents, ligands, or catalyst powders. Utilizing one catalytically active palladium milling ball, products could be formed in quantitative yield in as little as 30 min. In contrast to previous reports, the adjustment of milling parameters led to the complete elimination of abrasion from the catalyst ball, thus enabling the first reported systematic catalyst analysis. XPS, in situ XRD, and reference experiments provided evidence that the milling ball surface was the location of the catalysis, allowing a mechanism to be proposed. The versatility of the approach was demonstrated by extending the substrate scope to deactivated and even sterically hindered aryl iodides and bromides.

Accessing different binding sites of a multifunctional molecule: IR spectroscopy of propargyl alcoholwater complexes in helium droplets.

We report high-resolution infrared spectroscopic studies on complexes of propargyl alcohol with water (D2O) molecules, formed in superfluid helium droplets. The spectra were recorded in the frequency ranges of 2605-2700 cm-1 and 2730-2820 cm-1, covering the symmetric and antisymmetric stretching vibrations of the bound D2O. Mass-selective infrared spectroscopic measurements, a variation of the band intensities with dopant partial pressures (pickup curves) and ab initio calculations, performed at the MP2/6-311++G(d,p) level of theory, reveal the formation of two local minimum structures for the 1 : 1 PAD2O cluster. These structures are bound via O-HO (with water as the H-bond donor) and -C[triple bond, length as m-dash]C-HO (with propargyl alcohol as the H-bond donor) interactions and are less stable by 4.9 kJ mol-1 and 12.7 kJ mol-1, respectively, as compared to the global minimum structure for the complex.