Search results for "Proton"
showing 10 items of 5886 documents
Synthesis and Characterization of Copper Complexes Containing the Tripodal N7 Ligand Tris{2-[(pyridin-2-ylmethyl)amino]ethyl}amine (=N′-(Pyridin-2-yl…
2005
The stability constants of the CuII chelates with the tripodal heptadentate ligand tris{2-[(2-pyridylmethyl)amino]ethyl}amine (=N′-(pyridin-2-ylmethyl)-N,N-bis{2-[(pyridin-2-ylmethyl)amino]ethyl}ethane-1,2-diamine; tpaa), determined by potentiometry and UV spectrometry, show the formation of [Cu(tpaaH)]3+ and [Cu(tpaa)]2+ species. In the solid state, two mononuclear CuII compounds, [Cu(tpaa)](PF6)2 (1) and [Cu(tpaaH)](ClO4)3⋅H2O (2), and one trinuclear [Cu3(tpaa)2(ClO4)2](ClO4)4⋅2 H2O (3) complex were isolated and characterized by IR, UV/VIS, and EPR spectroscopy. An X-ray structure of the mononuclear protonated complex 2 shows that the Cu2+ ion has a distorted square-pyramidal geometry (τ=…
1H-NMR spectroscopic studies of paramagnetic superstructured iron(III) porphyrinsThis article is dedicated to the memory of Professor Michel Momentea…
2002
The electronic properties of several superstructured iron(III) porphyrins, in which the two faces of the porphyrin are protected by two chains linked at the opposite phenyl rings, have been investigated. The paramagnetic 1H NMR spectra of three iron(III) “basket-handle” porphyrins such as FeIII[e-BHP(C12)2], FeIII[a-BHP(C12)2] and FeIII[e-BHP(C12)(ImC11)] in organic solvent have been assigned. The 1H T1 values of the signals were measured and resonance assignments made based on NOESY and COSY experiments. The electronic structure of the iron(III) is discussed on the basis of the temperature dependence of the isotropic shifts and relaxation times. The hyperfine-shifted resonances in these sp…
Modeling the Geometric, Electronic, and Redox Properties of Iron(III)-Containing Amphiphiles with Asymmetric [NN′O] Headgroups
2011
Two iron(III)-containing amphiphiles 1 and 2 have been synthesized with the [NN'O] ligands HL(tBu-ODA) (2-((octadecyl(pyridin-2-ylmethyl)amino)methyl)-4,6-di-tert-butylphenol) and HL(I-ODA) (2-((octadecyl(pyridin-2-ylmethyl)amino)methyl)-4,6-diiodophenol), respectively. Compound 1 is monometallic, whereas EXAFS data suggest that 2 is a mixture of mono- and bimetallic species. The archetypical [Fe(III)(L(NN'O))(2)](+) complexes 3-9 have been isolated and characterized in order to understand the geometric, electronic, and redox properties of the amphiphiles. Preference for a monometallic or bimetallic nuclearity is dependent on (i) the nature of the solvent used for synthesis and (ii) the typ…
Two complexes of Pt(IV) and Au(III) with 2,2'-dipyridylamine and 2,2'-dipyridylaminide ligands
2014
Two noble metal complexes involving ancillary chloride ligands and chelating 2,2′-bipyridylamine (Hdpa) or its deprotonated derivative (dpa), namely [bis(pyridin-2-yl-κN)amine]tetrachloridoplatinum(IV), [PtCl4(C10H9N3)], and [bis(pyridin-2-yl-κN)aminido]dichloridogold(III), [AuCl2(C10H8N3)], are presented and structurally characterized. The metal atom in the former has a slightly distorted octahedral coordination environment, formed by four chloride ligands and two pyridyl N atoms of Hdpa, while the metal atom in the latter has a slightly distorted square-planar coordination environment, formed by two chloride ligands and two pyridyl N atoms of dpa. The difference in conjugation between the…
Defective dicubane-like tetranuclear nickel(II) cyanate and azide nanoscale magnets.
2010
Four tetrameric nickel(II) pseudohalide complexes have been synthesized and structurally, spectroscopically, and magnetically characterized. Compounds 1-3 are isostructural and exhibit the general formula [Ni(2)(dpk·OH)(dpk·CH(3)O)(L)(H(2)O)](2)A(2)·2H(2)O, where dpk = di-2-pyridylketone; L = N(3)(-), and A = ClO(4)(-) for 1, L = NCO(-) and A = ClO(4)(-) for 2, and L = NCO(-) and A = NO(3)(-) for 3. The formula for 4 is [Ni(4)(dpk·OH)(3) (dpk·CH(3)O)(2)(NCO)](BF(4))(2)·3H(2)O. The ligands dpk·OH(-) and dpk·CH(3)O(-) result from solvolysis and ulterior deprotonation of dpk in water and methanol, respectively. The four tetramers exhibit a dicubane-like core with two missing vertexes where the…
Generation, Characterization, and Electrochemical Behavior of the Palladium-Hydride Cluster [Pd3(dppm)3(3-CO)(3-H)]+ (dppm=Bis(diphenylphosphinometha…
2007
Addition of formate on the dicationic cluster [Pd(3)(dppm)(3)(mu(3)-CO)](2+) (dppm=bis(diphenylphosphinomethane) affords quantitatively the hydride cluster [Pd(3)(dppm)(3)(mu(3)-CO)(mu(3)-H)](+). This new palladium-hydride cluster has been characterised by (1)H NMR, (31)P NMR and UV/Vis spectroscopy and MALDI-TOF mass spectrometry. The unambiguous identification of the capping hydride was made from (2)H NMR spectroscopy by using DCO(2) (-) as starting material. The mechanism of the hydride complex formation was investigated by UV/Vis stopped-flow methods. The kinetic data are consistent with a two-step process involving: 1) host-guest interactions between HCO(2) (-) and [Pd(3)(dppm)(3)(mu(3…
Structural, magnetic, and spectroscopic comparative studies on four new derivatives of DIMMAL (2-di1H-2-imidazolylmethylmalonate): a novel generator …
2005
This paper reports the synthesis, structure solution, and magnetic characterization of four new DIMMAL-containing compounds (H 2 DIMMAL = 2-di1H-2-imidazolylmethylmalonic acid), H 2 DIMMAL.H 2 O (1), Na 2 (DIMMAL).5H 2 O (2), [Cu(HDIMMAL) 2 ] (3), and [Cu 2 (DIMMAL) 2 (H 2 O) 2 ].2H 2 O (4). Compound 1, containing two carboxylates and two protonated imidazole rings, adopts the dizwitterion configuration. These monohydrate MBBs pack together into a 3D array driven, as in the other three cases herein reported, by a combination of multiple-path H-bonds and aromatic-aromatic interactions. Compound 2 consists of centrosymmetric Na + tetramers in which four NaO 6 distorted octahedra are interconn…
Synthesis and crystal structures of palladium(II) complexes of 1,11-bis(2-pyridylmethyl)-1,4,8,11-tetraazacyclotetradecane-5,7-dione
2001
The two palladium(II) complexes, [PdL22222][ClO4]2·H2O 1 and [Pd(H−2L22222)]·H2O 2 with 1,11-bis(2-pyridylmethyl)-1,4,8,11-tetraazacyclotetradecane-5,7-dione, L22222, were prepared and characterized by X-ray crystallography and UV-visible spectroscopy. In 1 the palladium centre is co-ordinated by the tertiary amines of the macrocycle and the two pyridylmethyl nitrogens, forming a square-planar geometry in which two amide nitrogen groups remain protonated and do not take part in co-ordination. Moreover, there is a weak interaction between palladium and H(–N(8)) [d(PdII ⋯ H) = 2.90 A]. In contrast, 2 isolated under basic conditions has a square-planar geometry but the palladium ion is co-ordi…
Isomer Distribution and Interconversion in Cationic Allylpalladium(II) Complexes with 2-(Iminomethyl)pyridine Ligands
1997
The complexes [Pd(η3-allyl)(N-N‘)]ClO4 [allyl = 2-butenyl or 3-methyl-2-butenyl, N-N‘ = C5H3(6-R)N-2-CHNR‘ (R = H, R‘ = Me, CMe3, C6H4OMe-4; R = Me, R‘ = C6H4OMe-4) and C5H4N-2-CH2NMe2] are present in solution with different isomers, the structures of which may be assigned by an 1H NMR criterion based on chemical shift changes of the pyridine H(6) and/or of the allylic methyl protons, as confirmed also by 2D 1H NMR spectra. The isomer distribution depends mainly on the steric requirements of both the allyl and N-N‘ ligands: for [Pd(η3-3-methyl-2-butenyl)(N-N‘)]ClO4 the predominant isomer (ca. 100%) has a structure with the allylic methyl groups cis to the coordinated pyridine nitrogen when…
Catecholato complexes of o-phenylenebis(salicylideneiminato)iron(III) and meso-tetra(parasulphonatephenyl)porphyrinatoferrate(III). A comment on the …
1986
Abstract Formation of catecholato complexes of Fe(saloph) + and Fe(TPPS) 3− in solution is studied. Fe(saloph)(cat) − contains a cat 2− bidentate ligand. Its formation in solution competes efficiently with the hydrolysis and dimerization of Fe(saloph) + to give Fe 2 (saloph) 2 O. This behaviour shows that the planar saloph 2− ligand, as the analogous salen 2− , is easily distorted, and is not as rigid as generally considered. Iron(III) porphyrin Fe(TPPS) 3− with catechol gives the complex [Fe(TPPS)(Hcat)] 4− . Deprotonation of the unidentate Hcat − ligand cannot be studied because the smaller stability of the complex, and the dimerization of the metalloporphyrin dominates in basic medium. T…