Alkanes and [B12X12]2− (X = Cl, Br) are both stable compounds which are difficult to functionalize. Here we demonstrate the formation of a boron−carbon bond between these substances in a two-step process. Fragmentation of [B12X12]2− in the gas phase generates highly reactive [B12X11]− ions which spontaneously react with alkanes. The reaction mechanism was investigated using tandem mass spectrometry and gas-phase vibrational spectroscopy combined with electronic structure calculations. [B12X11]− reacts by an electrophilic substitution of a proton in an alkane resulting in a B−C bond formation. The product is a dianionic [B12X11CnH2n+1]2− species, to which H+ is electrostatically bound. High-flux ion soft landing was performed to codeposit [B12X11]− and complex organic molecules (phthalates) in thin layers on surfaces. Molecular structure analysis of the product films revealed that C−H functionalization by [B12X11]− occurred in the presence of other more reactive functional groups. This observation demonstrates the utility of highly reactive fragment ions for selective bond formation processes and may pave the way for the use of gas-phase ion chemistry for the generation of complex molecular structures in the condensed phase.

We use cryogenic ion vibrational spectroscopy to characterize the structure and fluxionality of the magic number boron cluster B . The infrared photodissociation (IRPD) spectrum of the D -tagged all- B isotopologue of B is reported in the spectral range from 435 to 1790 cm and unambiguously assigned to a planar boron double wheel structure based on a comparison to simulated IR spectra of low energy isomers from density-functional-theory (DFT) computations. Born-Oppenheimer DFT molecular dynamics simulations show that B exhibits internal quasi-rotation already at 100 K. Vibrational spectra derived from these simulations allow extracting the first spectroscopic evidence from the IRPD spectrum for the exceptional fluxionality of B .

We report infrared photodissociation (IRPD) spectra for the D2-tagged titanium oxide cluster anions (TiO2)n− with n = 3–8 in the spectral region from 450 to 1200 cm−1. The IRPD spectra are interpreted with the aid of harmonic spectra from BP86/6-311+G* density functional theory calculations of energetically low-lying isomers. We conclusively assign the IRPD spectra of the n = 3 and n = 6 clusters to global minimum energy structures with Cs and C2 symmetry, respectively. The vibrational spectra of the n = 4 and n = 7 clusters can be attributed to contributions of at most two low-lying structures. While our calculations indicate that the n = 5 and n = 8 clusters have many more low-lying isomers than the other clusters, the dominant contributions to their spectra can be assigned to the lowest energy structures. Through comparison between the calculated and experimental spectra, we can draw conclusions about the size-dependent evolution of the properties of (TiO2)n− clusters, and on their potential utility as model systems for catalysis on a bulk TiO2 surface.

We provide spectroscopic and computational evidence for a substantial change in structure and gas phase reactivity of Al3O4 + upon Fe-substitution, which is correctly predicted by multireference (MR) wave function calculations. Al3O4 + exhibits a cone-like structure with a central trivalent O atom (C3v symmetry). The replacement of the Al- by an Fe atom leads to a planar bicyclic frame with a terminal Al–O•– radical site, accompanied by a change from the Fe+III/O–II to the Fe+II/O–I valence state. The gas phase vibrational spectrum of Al2FeO4 + is exclusively reproduced by the latter structure, which MR wave function calculations correctly identify as the most stable isomer. This isomer of Al2FeO4 + is predicted to be highly reactive with respect to C–H bond activation, very similar to Al8O12 + which also features the terminal Al–O•– radical site. Density functional theory, in contrast, predicts a less reactive Al3O4 +-like “isomorphous substitution” structure of Al2FeO4 + to be the most stable one, except for functionals with very high admixture of Fock exchange (50%, BHLYP).

We use cryogenic ion trap vibrational spectroscopy in combination with density functional theory (DFT) to study the adsorption of up to four water molecules on AlO. The infrared photodissociation spectra of [AlO(DO)] are measured in the O-D stretching (3000-2000 cm) as well as the fingerprint spectral region (1300-400 cm) and are assigned based on a comparison with simulated harmonic infrared spectra for global minimum-energy structures obtained with DFT. We find that dissociative water adsorption is favored in all cases. The unambiguous assignment of the vibrational spectra of these gas phase model systems allows identifying characteristic spectral regions for O-D and O-H stretching modes of terminal (μ) and bridging (μ) hydroxyl groups in aluminum oxide/water systems, which sheds new light on controversial assignments for solid AlO phases.

The mechanism of dissociative D adsorption on TiO, which serves as a model for an oxygen vacancy on a titania surface, is studied using infrared photodissociation spectroscopy in combination with density functional theory calculations and a recently developed single-component artificial force induced reaction method. TiO readily reacts with D under multiple collision conditions in a gas-filled ion trap held at 16 K forming a global minimum-energy structure (DO-Ti-(O)-Ti(D)-O). The highly exergonic reaction proceeds quasi barrier-free via several intermediate species, involving heterolytic D-bond cleavage followed by D-atom migration. We show that, compared to neutral TiO, the excess negative charge in TiO is responsible for the substantial lowering of the D dissociation barrier, but does not affect the molecular D adsorption energy in the initial physisorption step.

S1. Quadrupole mass spectra S2. Experimental spectra compared to computed spectra for all the isomers S3. Additional possible isomers, spin densities and NBO charges S4. Isomer energies S5. Cartesian atomic coordinates of all calculated isomers S4

possible contributions from a kinetically trapped reactive intermediate in addition to the global minimum-energy isomer. From this work, we can draw conclusions about the size dependence and site-specificity of (TiO 2) n − cluster reactivity.