Search results for "Complexes"
showing 10 items of 875 documents
Bi-, Tetra-, and Hexanuclear AuI and Binuclear AgI Complexes and AgI Coordination Polymers Containing Phenylaminobis(phosphonite), PhN{P(OC6H4OMe-o)2…
2008
The reactions of phenylaminobis(phosphonite), PhN{P(OC6H4OMe-o)2}2 (1) (PNP), with [AuCl(SMe2)] in appropriate ratios, afford the bi- and mononuclear complexes, [(AuCl)2(µ-PNP)] (2) and [(AuCl)(PNP)]2 (3) in good yield. Treatment of 2 with 2 equiv of AgX (X = OTf or ClO4) followed by the addition of 1 or 2,2′-bipyridine affords [Au2(µ-PNP)2](OTf)2 (4) and [Au2(C10H8N2)2(µ-PNP)](ClO4)2 (5), respectively. Similarly, the macrocycles [Au4(C4H4N2)2(µ-PNP)2](ClO4)4 (6), [Au4(C10H8N2)2(µ-PNP)2](ClO4)4 (7), and [Au6(C3H3N3)2(µ-PNP)3](ClO4)6 (8) are obtained by treating 2 with pyrazine, 4,4′-bipyridine, or 1,3,5-triazine in the presence of AgClO4. The reaction of 1 with AgOTf in a 1:2 molar ratio pr…
Synthesis, structure and photophysical properties of a highly luminescent terpyridine-diphenylacetylene hybrid fluorophore and its metal complexes
2014
A new fluorescent terpyridyl-diphenylacetylene hybrid fluorophore 4'-[4-{(4-methoxyphenyl)ethynyl}phenyl]-2,2':6',2''-terpyridine, L, was synthesized via Sonogashira cross-coupling of 4'-(4-bromophenyl)-2,2':6',2''-terpyridine and 4-ethynylanisole in the presence of Pd(PPh3)4/CuI as a catalyst. The solid state structure of L shows a trans arrangement of pyridine nitrogen atoms along the interannular bond in the terpyridine domain. Five transition metal complexes of L, {[FeL2](CF3SO3)2 (1), [ZnL2](ClO4)2 (2), [CdL2](ClO4)2 (3), [RuL2](PF6)2 (4), and PtMe3IL (5)}, have also been synthesized and characterized by spectroscopic methods and single crystal X-ray analysis. The X-ray crystal structu…
Synthesis, structure and photophysical properties of a highly luminescent terpyridine-diphenylacetylene hybrid fluorophore and its metal complexes
2015
A new fluorescent terpyridyl-diphenylacetylene hybrid fluorophore 4′-[4-{(4-methoxyphenyl)ethynyl}phenyl]-2,2′:6′,2′′-terpyridine, L, was synthesized via Sonogashira cross-coupling of 4′-(4-bromophenyl)-2,2′:6′,2′′-terpyridine and 4-ethynylanisole in the presence of Pd(PPh3)4/CuI as a catalyst. The solid state structure of L shows a trans arrangement of pyridine nitrogen atoms along the interannular bond in the terpyridine domain. Five transition metal complexes of L, {[FeL2](CF3SO3)2 (1), [ZnL2](ClO4)2 (2), [CdL2](ClO4)2 (3), [RuL2](PF6)2 (4), and PtMe3IL (5)}, have also been synthesized and characterized by spectroscopic methods and single crystal X-ray analysis. The X-ray crystal structu…
Tuning the Electrochemistry of Free-Base Porphyrins in Acidic Nonaqueous Media: Influence of Solvent, Supporting Electrolyte, and Ring Substituents
2016
International audience; A detailed study of reduction potentials, electroreduction mechanisms and acid-base chemistry was carried out on two series of free-base porphyrins in nonaqueous media. The first series is represented by four-pyrrole substituted tetraphenylporphyrin (TPP) derivatives, two of which are planar and two of which are nonplanar in their non-protonated form. The second comprises porphyrins with 0-4 meso-phenyl groups on the macrocycle. Equilibrium constants for conversion of each neutral porphyrin to its diprotic [H4P] 2+ form were determined and the electrochemistry was then elucidated as a function of: (i) type of nonaqueous solvent, (ii) anion of supporting electrolyte, …
Membrane Protein Complexes: Structure and Function
2018
This edited book contains a compilation of 14 advanced academic chapters dealing with the structure and function of membrane protein complexes. This rapidly advancing important field of study closely parallels those on soluble protein complexes, and viral protein and nucleoprotein complexes.Diverse topics are included in this book, ranging from membrane–bound enzymes to ion channels, proton pumps and photosystems. Data from X-ray crystallography, cryo-electron microscopy and other biophysical and biochemical techniques are presented throughout the book. There is extensive use of colour figures of protein structures. Throughout the book structure and function are closely correlated.The two e…
Communication between iron(II) building blocks in cooperative spin transition phenomena
2003
[EN] In the present article we discuss the cooperative nature of the spin crossover phenomenon in iron(II) complexes, providing a perspective of the state of the art in this area. The first aspect we discuss is the role of the intermolecular interactions, more precisely the ¿-interactions, in mononuclear complexes. We show that by playing with the nature of the ligands, aliphatic, aromatic, or extended aromatic, it is possible to create stronger cohesive forces and receive a more cooperative response from the compound. In the next step the singular family of bipyrimidine-bridged iron(II) dinuclear compounds is presented as the simplest example of polynuclear spin crossover complexes exhibit…
Complex-forming properties of peat humic acids from a raised bog profiles
2013
Abstract Humic substances (HS) belong to the most powerful complex-forming agents, significantly affecting major and trace element speciation in natural environment. Several authors have focused on humic–metal interactions, using differing methods and comparing humic substances on different sources. However, the intrinsic differences among the HS of different origin and the impact of humification degree on the complex formation between humic substances and metals have not received the necessary attention until now. The aim of this study is to determine the Cu(II) complexing capacity and stability constants of Cu(II) complexes of humic acids (HA) isolated from two well-characterized raised b…
A Germanium Isocyanide Complex Featuring (n → π*) Back-Bonding and Its Conversion to a Hydride/Cyanide Product via C-H Bond Activation under Mild Con…
2012
Reaction of the diarylgermylene Ge(ArMe6)2 [ArMe6 = C6H3-2,6-(C6H2-2,4,6-(CH3)3)2] with tert-butyl isocyanide gave the Lewis adduct species (ArMe6)2GeCNBut, in which the isocyanide ligand displays a decreased C–N stretching frequency consistent with an n → π* back-bonding interaction. Density functional theory confirmed that the HOMO is a Ge–C bonding combination between the lone pair of electrons on the germanium atom and the C–N π* orbital of the isocyanide ligand. The complex undergoes facile C–H bond activation to produce a new diarylgermanium hydride/cyanide species and isobutene via heterolytic cleavage of the N–But bond. peerReviewed
Interplay of acidity and ionic liquid structure on the outcome of a heterocyclic rearrangement reaction
2021
The study of suitable probe reactions is a powerful tool to investigate the properties of nonconventional solvents such ionic liquids (ILs). In particular, we studied the acid-catalyzed mononuclear rearrangement of heterocycles (MHR) of the Z-phenylhydrazone of 5-amino-3-benzoyl-1,2,4-oxadiazole into the relevant 1,2,3-triazole, in solution of ILs by means of kinetic measurements. We chose as solvents six ILs differing both in the cation and anion, in the presence of five carboxylic and sulfonic acids as catalysts. For a useful comparison, the reaction was also performed in 1,4-dioxane and methanol. In general, the reaction occurs faster in ILs, compared to conventional solvents, according …
A three-coordinate iron–silylene complex stabilized by ligand–ligand dispersion forces
2016
The structural and bonding properties of a three-coordinate N-heterocyclic silyene (NHSi) complex of the iron(II) amide [Fe{N(SiMe3)2}2] are reported. Computational studies reveal that dispersion forces between the amido SiMe3 substituents and the isopropyl substituents on the NHSi ligand significantly enhance the stability of the complex, along with Fe-to-Si π-backbonding. peerReviewed