52337-68-5Relevant articles and documents
Self-assembly of novel macrocyclic aminomethylphosphines with hydrophobic intramolecular cavities
Balueva, Anna S.,Kuznetsov, Roman M.,Ignat'eva, Svetlana N.,Karasik, Andrey A.,Gubaidullin, Aidar T.,Litvinov, Igor A.,Sinyashin, Oleg G.,Loennecke, Peter,Hey-Hawkins, Evamarie
, p. 442 - 447 (2004)
Novel macroheterocyclic tetraphosphines, namely, 1,1′,5,5′- bis(arylene)-bis(1,5-diaza-3,7-diphosphacyclooctanes) 2-6, were obtained without the use of high-dilution techniques or any matrix by the reaction of bis(hydroxymethyl)-organylphosphines with primary aromatic diamines containing two p-phenylene fragments linked by various one-atom bridges in a molecular self-assembly process. The structures of 4, 5 and 6 were investigated by X-ray crystal structure analyses. The macrocyclic cavities can be described as a truncated rhombohedral prism with side faces formed by phenylene rings and 1,5-diaza-3,7-diphosphacyclooctanes in the truncated acute angles. In the crystals of these macrocycles, solvating DMF molecules are present, and a methyl group from each of two DMF molecules penetrates the macrocyclic cavities of 4 and 5 from either side, whereas only one disordered molecule of DMF penetrates the cavity of macrocycle 6. Different types of crystal packing are observed for the P-benzyl-substituted compounds 4 and 5 and for the P-mesityl-substituted compound 6: for 4 and 5 the formation of alternating layers containing the macrocycles and the DMF molecules is observed, in which the cavities of the macrocyclic molecules form channels and the DMF molecules are located in the centers of the channels; in the crystal of 6, six molecules are arranged around the 3 axis in the fashion of a six-bladed propeller.
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.