The adsorption of silver atoms, dimers, tetramers, and octamers on the perfect anatase (100) surface has been studied theoretically at density functional theory level. Two complementary approaches based on linear combinations of atom-centered Gaussian-type basis functions and plane waves were applied. The most preferable adsorption positions were found to be hollow sites between two-coordinated oxygen atoms (O(2c)). Adsorption on the Ti–O planes is energetically less favorable. The binding mechanism was interpreted in terms of the interaction between cluster orbitals and orbitals of O(2c) atoms. The charge transfer leads to a deformation of the cluster shape compared with the stable gas-phase structures. In the Ti–O plane sites, an additional binding mechanism exists through the overlap between the silver cluster’s HOMO and unoccupied orbitals of five-coordinated titanium atoms. The same bonding mechanisms have been found previously for the adsorption of Ag particles on the rutile (110) surface1. The growth of silver clusters on the anatase (100) surface via aggregation is an exothermic process and leads to the formation of three-dimensional structures.

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The ferrocene halogen “dance” has been deemed hardly controllable. Here, we describe the first efficient examples of this reaction. Conversion of 1-fluoro-2-iodo (or 1-chloro-2-iodo) to 1-fluoro-3-iodo (or 1-chloro-3-iodo) ferrocenes was ensured by suitably protecting the free 5-position.

Two methods were compared to convert ferrocene into N,N-diisopropylferrocenecarboxamide, N,N-diethylferrocenecarboxamide, N,N-dimethylferrocenecarboxamide and (4-morpholinocarbonyl)ferrocene, namely deprotometalation followed by trapping using dialkylcarbamoyl chlorides and amide formation from the intermediate carboxylic acid. The four ferrocenecarboxamides were functionalized at C 2 ; in the case of the less hindered and more sensitive amides, recourse to a mixed lithium-zinc 2,2,6,6-tetramethylpiperidinobased base allowed to achieve the reactions. Halogen migration using lithium amides was next optimized. Whereas it appeared impossible to isolate the less hindered 3-iodoferrocenecarboxamides, 3-iodo-N,N-diisopropylferrocenecarboxamide proved stable and was converted to new 1,3-disubstituted ferrocenes by Suzuki coupling or amide reduction. DFT calculations were used to rationalize the results obtained.

A theoretical study of nitric oxide (NO) conversion on the anatase (100) surface covered with silver clusters has been performed. Two complementary approaches based on density functional theory (DFT) have been applied, in which the electron density was expanded in plane waves and in atom-centered Gaussian-type orbitals, respectively. It was observed that the NO interaction with the surface occurs mainly via the N atom. Adsorption of NO on silver clusters or at the border between silver and the TiO2 surface is more exothermic than at the uncovered anatase surface. Therefore, all stages of NO degradation proceed mainly on these active sites. Further adsorption of NO molecules leads to the formation of dimer species with previously adsorbed ones. Only acyclic cis-isomers of ONNO are formed according to the calculated energies. An analysis of electron density shows that the LUMO of adsorbed (NO)2 becomes partially occupied so that the adsorbed nitric oxide dimers are negatively charged. As a result of this charge transfer, the (NO)2 species are decomposed by breaking one or two N–O bonds, followed by the formation and desorption of N2 or N2O. In the case of decomposition at silver-surface boundaries, the main gas-phase product is N2O, whereas on the silver cluster both N2 and N2O are formed. After the (NO)2 decomposition, oxygen atoms remain on the surface and can further react with NO molecules from the gas phase, leading to the formation of rather tightly bound nitrogen dioxide molecules.