75593-74-7Relevant academic research and scientific papers
Catalyst Pendent-Base Effects on Cyclization of Alkynyl Amines
Stubbs, James M.,Chapple, Devon E.,Boyle, Paul D.,Blacquiere, Johanna M.
, p. 3694 - 3702 (2018/08/06)
A family of [CpRu(PP)(MeCN)]PF6 complexes (2 a–e and 4) were prepared in which the bis-phosphine ligand contains a pendent tertiary amine in the second-coordination sphere. 2 a–e contain PPh2NR′2 ligands with two amine groups as the pendent base. Complex 4 has the PPh2NPh1 ligand with only one pendent amine. The catalytic performance of 2 a–e and 4 were assessed in the cyclization of 2-ethynyl aniline and 2-ethynylbenzyl alcohol. It was revealed that the positioning of the pendent amine near the metal active site is essential for high catalyst performance. A comparison of PPh2NR′2 catalysts (2 a–e) showed minimal difference in performance as a function of pendent amine basicity. Rather, only a threshold basicity – in which the pendent amine was more basic than the substrate – was required for high performance.
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.
Electrocatalytic oxidation of formate by [Ni(PR 2NR′2)2(CH3CN)] 2+ complexes
Galan, Brandon R.,Schoeffel, Julia,Linehan, John C.,Seu, Candace,Appel, Aaron M.,Roberts, John A. S.,Helm, Monte L.,Kilgore, Uriah J.,Yang, Jenny Y.,Dubois, Daniel L.,Kubiak, Clifford P.
experimental part, p. 12767 - 12779 (2011/10/05)
[Ni(PR2NR′2) 2(CH3CN)]2+ complexes with R = Ph, R′ = 4-MeOPh or R = Cy, R′ = Ph, and a mixed-ligand [Ni(PR 2NR′2)(PR′′ 2NR′
