Molecular reduction

Uni-molecular reductive elimination provides the simplest possible route for generation of H2. 

A number of complexes were reported in the literature including H2Fe(CO)4 [34], H2RhCl(PPh3)3, H2lrCl(CO)(PPh3)2 and H2Co[P(OR)3]4, which follows uni-molecular reductive elimination mechanism for H2. Reports are also available on bimolecular reductive elimination mechanism for the H2 elimination. 

Baran reported an iron-eatalysed reductive alkene eoupling using phe-nylsilane as the hydrogen source. Using a simple proeedure, both inter-molecular reductive alkene coupling and intramolecular reductive cyclisation were possible. 

The intra- and inter-molecular reductive self-coupling of vinyl bromides may be achieved using a catalytic amount of palladium... 

Friis and coworkers [80] considered an intermediate mechanism, in which an electron first transfers to the molecule and the molecule begins to relax towards the reduced state. However, before it is fully relaxed to the reduced state, an electron transfer from the molecule to the second electrode occurs when the temporarily occupied level passes the Fermi level of the second electrode. They called this process coherent two-step electron transfer. More recently, Kuznetsov and Ulstrup [81] have developed a systematic theory for the sequential two-step process. The electron transfers from one electrode to the molecule and reduces the molecule, and then transfers to the second electrode and reoxidizes the molecule, so the process is reviewed as a cycle of consecutive molecular reduction and reoxidation. A particular interesting feature in the theory is that each reduction-reoxidation cycle is composed of a large number of individual electron transfer events between the molecule and both the tip and the substrate. This significantly enhances the tunneling current compared to a single electron transfer. 

Quinazoline derivatives (68) have been obtained via the w/er-molecular reductive N-heterocyclisation of 2-nitrobenzaldehyde or 2-nitrophenylketones (67) with formamide in the presence of CO, catalysed by a PdCl2(PPh3)2/MoCls system (eq. 30) [103] ... 

Thermo-oxidation increases the degradation rates considerably. During this type of degradation both molecular reduction and molecular enlargement reactions occur [9]. In starch-filled LDPE containing pro-oxidant in addition to starch it was shown that oxidation at 100°C initiates carbonyl formation after 5 days compared to pure LDPE which is unaffected under the same conditions at [10]. 

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