The experimental study of the bonding geometry of a (100)Ge surface exposed to H2S in the gas phase at 330°C shows that 1 ML S coverage with (2×1) surface reconstruction can be achieved. The amount of S on the Ge surface and the observed surface periodicity can be explained by the formation of disulfide bridges between Ge–Ge dimers on the surface. First-principles molecular dynamics simulations confirm the preserved (2×1) reconstruction after dissociative adsorption of H2S molecules on a (100)Ge (2×1) surface, and predict the formation of (S–H)–(S–H) inter-Ge dimer bridges, i.e., disulfide bridges interacting via hydrogen bonding. The computed energy band gap of this atomic configuration is shown to be free of surface states, a very important finding for the potential application of Ge in future high performance integrated circuits.
Ribonucleotide reductases (RNRs) are essential enzymes required for DNA synthesis. In class Ib Mn2 RNRs superoxide (O2.−) was postulated to react with the MnII2 core to yield a MnIIMnIII‐peroxide moiety. The reactivity of complex 1 ([MnII2(O2CCH3)2(BPMP)](ClO4), where HBPMP=2,6‐bis{[(bis(2‐pyridylmethyl)amino]methyl}‐4‐methylphenol) towards O2.− was investigated at −90 °C, generating a metastable species, 2. The electronic absorption spectrum of 2 displayed features (λmax=440, 590 nm) characteristic of a MnIIMnIII‐peroxide species, representing just the second example of such. Electron paramagnetic resonance and X‐ray absorption spectroscopies, and mass spectrometry supported the formulation of 2 as a MnIIMnIII‐peroxide complex. Unlike all other previously reported Mn2‐peroxides, which were unreactive, 2 proved to be a capable oxidant in aldehyde deformylation. Our studies provide insight into the mechanism of O2‐activation in Class Ib Mn2 RNRs, and the highly reactive intermediates in their catalytic cycle.
scite is a Brooklyn-based organization that helps researchers better discover and understand research articles through Smart Citations–citations that display the context of the citation and describe whether the article provides supporting or contrasting evidence. scite is used by students and researchers from around the world and is funded in part by the National Science Foundation and the National Institute on Drug Abuse of the National Institutes of Health.