Vibrational spectroscopy of Cu(H): about anharmonicity and fluxionality.

The vibrational spectra of the copper(I) cation-dihydrogen complexes Cu(H), Cu(D) and Cu(D)H are studied using cryogenic ion trap vibrational spectroscopy in combination with quantum chemical calculations. The infrared photodissociation (IRPD) spectra (2500-7300 cm) are assigned based on a comparison to IR spectra calculated using vibrational second-order perturbation theory (VPT2). The IRPD spectra exhibit ≈60 cm broad bands that lack rotational resolution, indicative of rather floppy complexes even at an ion trap temperature of 10 K.

Infrared photodissociation spectroscopy of (AlO)FeO: influence of Fe-substitution on small alumina clusters.

The infrared photodissociation spectra of He-tagged (AlO)FeO ( = 2-5), are reported in the Al-O and Fe-O stretching and bending spectral region (430-1200 cm) and assigned based on calculated harmonic IR spectra from density functional theory (DFT). The substitution of Fe for an Al center occurs preferentially at 3-fold oxygen coordination sites located at the cluster rim and with the Fe atom in the +III oxidation state. The accompanying elongation of metal oxygen bonds leaves the Al-O network structure nearly unperturbed (isomorphous substitution).

Valence and Structure Isomerism of AlFeO: Synergy of Spectroscopy and Quantum Chemistry.

We provide spectroscopic and computational evidence for a substantial change in structure and gas phase reactivity of AlO upon Fe-substitution, which is correctly predicted by multireference (MR) wave function calculations. AlO exhibits a cone-like structure with a central trivalent O atom (C 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/O to the Fe/O valence state.

Structure and Reactivity of Al-O(H)-Al Moieties in Siloxide Frameworks: Solution and Gas-Phase Model Studies.

Even though aluminas and aluminosilicates have found widespread application, a consistent molecular understanding of their surface heterogeneity and the behavior of defects resulting from hydroxylation/dehydroxylation remains unclear. Here, we study the well-defined molecular model compound, [Al (μ -OH) (THF) (PhSi(OSiPh O) ) ], 1, to gain insight into the acid-base reactivity of cyclic trinuclear Al (μ -OH) moieties at the atomic level. We find that, like zeolites, they are sufficiently acidic to catalyze the isomerization of olefins.