953389-63-4Relevant academic research and scientific papers
Electro- and photocatalytic hydrogen evolution by a cobalt complex based on a tripodal iminopyridine ligand
Song, Xiaowei,Wen, Huimin,Ma, Chengbing,Chen, Changneng
, p. 639 - 645 (2014)
A cobalt complex based on the tripodal iminopyridine type ligand (2E)-2-N-(pyridin-2-ylmethylidene)-1-N,1-N-bis({2-[(E)-(pyridin-2-ylmethylidene) amino]phenyl})benzene-1,2-diamine (L1), namely, [CoL1](BF4) 2 (1a), was synthesized and characterized by FT-IR, UV-Vis spectroscopy, magnetic moment and elemental analysis. X-ray structural study of 1a shows that the complex is coordinatively saturated and contains the uncoordinated bridgehead nitrogen atom. Electrochemical studies reveal that the complex 1a has an electrocatalytic proton reduction activity in acetonitrile, when using acetic acid as a proton source with icat/ip ～ 3.3. Therefore we estimate that the complex 1a could give the highest TOF of 2.3 s-1 for the reduction of proton to hydrogen. Furthermore, under visible-light irradiation, an optimized H2 evolution system containing 1a (0.1 mM), [Ir(ppy)2(bpy)](PF6) (0.1 mM), and 10 vol% TEA in CH3CN-H2O (1/1, v/v) mixed solvents at pH 10 gives a highest turnover number of 34. For comparison, an electron-withdrawing ester group (CO2CH2CH3) is introduced into the pyridine moiety of the ligand as in L2, however, which leads to its corresponding cobalt complex 2a less active than the complex 1a for electro- and photocatalytic H2 evolution. Additionally, the control experiment establishes that the isostructural zinc complex [ZnL1](BF 4)2 (1b) is ineffective for H2 generation.
Synthesis and characterization of a series of structurally and electronically diverse Fe(II) complexes featuring a family of triphenylamido-amine ligands
Paraskevopoulou, Patrina,Ai, Lin,Wang, Qiuwen,Pinnapareddy, Devender,Acharyya, Rama,Dinda, Rupam,Das, Purak,Celenligil-Cetin, Remle,Floros, Georgios,Sanakis, Yiannis,Choudhury, Amitava,Rath, Nigam P.,Stavropoulos, Pericles
scheme or table, p. 108 - 122 (2010/03/04)
A family of triphenylamido-amine ligands of the general stoichiometry LxH3=[R-NH-(2-C6H4)]3N (R=4-t-BuPh (L1H3), 3,5-t-Bu2Ph (L 2H3), 3,5-(CF3)2Ph (L 3H3), CO-Z-Bu (L4H3), 3,5-Cl 2Ph (L5H3), COPh (L6H3), CO-i-Pr (L7H3), COCF3 (L8H 3), has been synthesized and characterized, featuring a rigid triphenylamido-amine scaffold and an array of stereoelectronically diverse aryl, acyl, and alkyl substituents (R). These ligands are deprotonated by potassium hydride in THF or DMA and reacted with anhydrous FeCI2 to afford a series of ferrous complexes, exhibiting stoichiometric variation and structural complexity. The prevalent [(Lx)Fe(II)-SoIv]- structures (Lx=L1, L2, L3, L5, Solv=THF; Lx=L8, solv=DMA; Lx=L6, L8, Solv=MeCN) reveal a distorted trigonal bipyramidal geometry, featuring ligand-derived [N3,amidoNamine] coordination and solvent attachment trans to the Namine atom. Specifically for [(L8)Fe(ll)-DMA]-, a Namido residue is coordinated as the corresponding Nimino moiety (Fe-N(Ar)=C(CF3)-O-). In contrast, compounds [(L4)Fe(ll)] [(L6)2Fe(ll)2]2-, [K(L 7)2Fe(ll)2]22-, and [K(L9)Fe]2 are all solvent-free in their coordination sphere and exhibit four-coordinate geometries of significant diversity. In particular, [(L4)Fe(ll)]- demonstrates coordination of one amidato residue via the O-atom end (Fe-O-C(t-Bu)=N(Ar)). Furthermore, [(L6)2Fe(ll) 2]2- and [K(L7)2Fe(ll) 2]22- are similar structures exhibiting bridging amidato residues (Fe-N(Ar)C(R)=O-Fe) in dimeric structural units. Finally, the structure of [K(L9)Fe]2 is the only example featuring a minimal [N3,amidodoNamine] coordination sphere around each Fe(II) site. All compounds have been characterized by a variety of physicochemical techniques, including Moessbauer spectroscopy and electrochemistry, to reveal electronic attributes that are responsible for a range of Fe(ll)/Fe(lll) redox potentials exceeding 1.0 V.
