5958-45-2Relevant articles and documents
Coordination and conformational isomers in mononuclear iron complexes with pertinence to the [FeFe] hydrogenase active site
Orthaber, Andreas,Karnahl, Michael,Tschierlei, Stefanie,Streich, Daniel,Stein, Matthias,Ott, Sascha
, p. 4537 - 4549 (2014/03/21)
A series of six mononuclear iron complexes of the type [Fe(X-bdt)(P R2NPh2)(CO)] (PR 2NPh2 = 1,5-diaza-3,7-diphosphaoctane, bdt = benzenedithiolate with X = H, Cl2 or Me and R = Ph, Bn, Cyc or tert-Bu) was prepared. This new class of penta-coordinate iron complexes contains a free coordination site and a pendant base as essential structural features of the [FeFe]-hydrogenase active site. The bidentate nature of the PR2NPh2 ligands was found to be crucial for the preferential formation of coordinatively unsaturated penta-coordinate complexes, which is supported by first principle calculations. IR-spectroscopic data suggest the presence of coordination isomers around the metal center, as well as multiple possible conformers of the PR 2NPh2 ligand. This finding is further corroborated by X-ray crystallographic and computational studies. 31P{1H}-NMR- and IR-spectroscopic as well as electrochemical measurements show that the electronic properties of the complexes are strongly, and independently, influenced by the P-substituents at the PR2NPh2 ligand as well as by modifications of the bdt bridge. These results illustrate the advantages of this modular platform, which allows independent and selective tuning through site specific modifications. Potential catalytic intermediates, namely singly reduced and protonated complexes, have been further investigated by spectroscopic methods and exhibit remarkable stability. Finally, their general capacity for electro-catalytic reduction of protons to molecular hydrogen was verified.
Suzuki-Miyaura cross-coupling coupling reactions with low catalyst loading: A green and sustainable protocol in pure water
Fihri, Aziz,Luart, Denis,Len, Christophe,Solhy, Abderrahim,Chevrin, Carole,Polshettiwar, Vivek
experimental part, p. 3116 - 3121 (2011/05/03)
The Suzuki-Miyaura coupling reaction represents one of the most important synthetic transformations developed in the 20th century. However, the use of toxic organic solvents remains a scientific challenge and an aspect of economical and ecological relevance, and benign water as a reaction medium was found to be highly effective to overcome some of these issues. In the present manuscript, we described Suzuki-Miyaura coupling reactions in neat water, without using any phase transfer reagent. Notably, this protocol also works with ultra-low loading of catalyst with high turnover numbers and also able to couple challenging substrates like aryl chlorides.