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D G Nocera

Publications and source records attributed to D G Nocera.

5 recordsLinked to original sources
PubMed2001

Hydrogen produced from hydrohalic acid solutions by a two-electron mixed-valence photocatalyst.

Energy conversion cycles are aimed at driving unfavorable, small-molecule activation reactions with a photon harnessed by a transition metal complex. A challenge that has occupied researchers for several decades is to create molecular photocatalysts to promote the production of hydrogen from homogeneous solution. We now report the use of a two-electron mixed-valence dirhodium compound to photocatalyze the reduction of hydrohalic acid to hydrogen. In this cycle, photons break two RhII-X bonds of a LRh0-RhIIX2 core in the presence of a halogen trap to regenerate the active LRh0-Rh0 catalyst, which reacts with hydrohalic acid to produce hydrogen.

Journal Article↗
PubMed2000

The whole story of the two-electron bond, with the delta bond as a paradigm.

It is shown that the delta bond, as found particularly in the Re(2)(6+) and Mo(2)(4+) cores of hundreds of compounds, provides a paradigm for the behavior of two-electron bonds of all types. By control of the angle of twist around the M-M axis, the strength of the bond can be systematically varied. By means of conventional electronic spectroscopy, nuclear magnetic resonance spectroscopy, and two-photon excitation spectroscopy, the entire picture of the manifold of four states for two electrons bonding two atoms, as first described by Coulson and Fischer in 1949, has been confirmed.

Electrons↗
PubMed1998

Proton-coupled electron transfer.

Proton-coupled electron transfer (PCET) is an important mechanism for charge transfer in a wide variety of systems including biology- and materials-oriented venues. We review several areas where the transfer of an electron and proton is tightly coupled and discuss model systems that can provide an experimental basis for a test of PCET theory. In a PCET reaction, the electron and proton may transfer consecutively (ET/PT) or concertedly (ETPT). The distinction between these processes is formulated, and rate-constant expressions for the two reaction channels are presented. Methods for the evaluation of these rate constants are discussed that are based on dielectric continuum theory. Electron donor hydrogen-bonded-interface electron acceptor systems displaying PCET reactivity are presented, and the rate-constant expressions corresponding to the ETPT and ET/PT channels for several model reaction complexes are evaluated.

Electron Transport↗