3-Deoxy-D-erythro-hexos-2-ulose bis(thiosemicarbazone) copper(II) chelate. Studies in solution and in the solid state

1999 ◽  
Vol 77 (9) ◽  
pp. 1492-1497 ◽  
Author(s):  
Sandra Signorella ◽  
Claudia Palopoli ◽  
Alejandro Frutos ◽  
Graciela Escandar ◽  
Tomoaki Tanase ◽  
...  
Keyword(s):  
Structural Parameters ◽  
Structure Stability ◽  
Planar Geometry ◽  
Powdered Sample ◽  
Coordination Geometry ◽  
Spectra Analysis ◽  
X Ray ◽  
Local Coordination ◽  
Square Planar ◽  
X Ray Absorption

The 3-deoxy-D-erythro-hexos-2-ulose bis(thiosemicarbazone) (LH2) acts as a tetradentate ligand with S2N2 donor sites to form a copper(II) chelate (Cu(II)L). The Cu K-edge X-ray absorption spectra analysis of a powdered sample revealed a square-planar S2N2 local coordination geometry with average Cu—N and Cu—S distances of 1.92 and 2.33 Å. The EXAFS and XANES spectra and the structural parameters of a DMF solution sample indicate the retention of the square-planar local structure of the Cu(II)S2N2 chromophore upon dissolution. Semiempirical PM3 calculations indicate that the structure of Cu(II)L with the copper(II) ion bound to the S2N2 donor set disposed in a square-planar geometry is the most favorable one (with the highest |ΔHf |). The formation constant (log Kf = 20.65 ± 0.06) of the neutral [CuL] species was calculated in 30% v/v dioxane-water and the protonation and deprotonation constants determined.Key words: bis(thiosemicarbazone), copper(II), chelate, structure, stability constant.

Local coordination geometry around Cu and Cu ions in silicate glasses: an X-ray absorption near edge structure investigation

2000 ◽  
Vol 14 (2) ◽  
pp. 211-216 ◽  
Author(s):  
C. Maurizio ◽  
F. d'Acapito ◽  
M. Benfatto ◽  
S. Mobilio ◽  
E. Cattaruzza ◽  
...  
Keyword(s):  
Silicate Glasses ◽  
Coordination Geometry ◽  
Structure Investigation ◽  
Edge Structure ◽  
X Ray ◽  
Local Coordination ◽  
X Ray Absorption ◽  
Cu Ions

Hemilabile imino-phosphine palladium(II) complexes: synthesis, molecular structure, and evaluation in Heck reactions

2014 ◽  
Vol 68 (7) ◽  
Author(s):  
William Motswainyana ◽  
Martin Onani ◽  
Roger Lalancette ◽  
Paul Tarus
Keyword(s):  
Molecular Structure ◽  
Planar Geometry ◽  
Coordination Geometry ◽  
Coupling Reactions ◽  
Heck Coupling ◽  
Heck Reactions ◽  
Reaction Conditions ◽  
X Ray ◽  
X Ray Crystallography ◽  
Square Planar

AbstractThe ligands 2-(diphenylphosphino)benzyl-(2-thiophene)methylimine (V) and 2-(diphenylphosphino) benzyl-(2-thiophene)ethylimine (VI) were prepared from 2-(diphenylphosphino)benzaldehyde and thiophene amines with very good yields. An equimolar reaction of V and VI with either PdCl2(cod) (cod = cyclooctadiene) or PdClMe(cod) afforded palladium(II) complexes I–IV. The molecular structure of II was confirmed by X-ray crystallography. The coordination geometry around the palladium atom exhibited distorted square planar geometry at the palladium centre. Complexes I, II, and IV were evaluated as catalysts for Heck coupling reactions of iodobenzene with methyl acrylate under mild reaction conditions; 0.1 mole % catalyst, Et3N base, MeCN reflux for 8 h, 80°C; isolated yield on a 10 mmol scale with catalyst I (64 %), II (68 %), and IV (58 %). They all exhibited significant activities.

Synthesis and structural studies of rhodium complexes of phosphorus—sulfur ligands

1986 ◽  
Vol 64 (9) ◽  
pp. 1870-1875 ◽  
Author(s):  
David G. Dick ◽  
Douglas W. Stephan
Keyword(s):  
Single Crystal ◽  
Planar Geometry ◽  
Methyl Groups ◽  
Rhodium Complexes ◽  
Coordination Geometry ◽  
Structural Studies ◽  
X Ray Diffraction ◽  
Space Group ◽  
X Ray ◽  
Square Planar

Rhodium complexes of the phosphorus—sulfur ligands, 2-diphenylphosphinoethyl methyl sulfide (MeSP), 1, and 2-diphenylphosphinothiophene (PTH), 2, have been prepared and studied by single crystal X-ray diffraction methods. [Rh(MeSP)2]BF4•H2O, 3, crystallizes in the space group P21/n with a = 16.939(6) Å, b = 17.152(5) Å, c = 12.049(9) Å, β = 106.50(4)°, and Z = 4. The MeSP ligands chelate to Rh yielding a distorted square-planar geometry. The disposition of the methyl groups on the cis sulfur atoms is transoid. Average Rh—P and Rh—S bond distances were found to be 2.225(3) and 2.347(3) Å, respectively. [Rh(PTH)2(COD)]BF4, 4, crystallizes in the space group Cc with a = 15.862(2) Å, b = 15.112(3) Å, c = 16.029(3) Å, β = 103.32(1)°, and Z = 4. The Rh atom in 4 also has essentially a square-planar coordination geometry. 2 does not chelate but rather is monohapto through phosphorus. Rh—P distances of 2.319(3) and 2.378(3) Å and Rh—C distances of 2.17(1), 2.22(1), 2.24(1), and 2.27(1) Å were found. The small variations in the Rh—P and Rh—C bonds distances appear to be a result of steric interactions between 2 and the COD ligand.

Extended X-ray absorption fine structure and multiple-scattering simulation of nickel dithiolene complexes Ni[S2C2(CF3)2]2n(n= −2, −1, 0) and an olefin adduct Ni[S2C2(CF3)2]2(1-hexene)

2015 ◽  
Vol 22 (1) ◽  
pp. 124-129 ◽  
Author(s):  
Weiwei Gu ◽  
Hongxin Wang ◽  
Kun Wang
Keyword(s):  
Fine Structure ◽  
Multiple Scattering ◽  
Edge Structure ◽  
X Ray ◽  
Absorption Fine ◽  
Square Planar ◽  
Square Planar Complexes ◽  
Uv Visible ◽  
Edge Features ◽  
X Ray Absorption

A series of Ni dithiolene complexes Ni[S2C2(CF3)]2n(n= −2, −1, 0) (1,2,3) and a 1-hexene adduct Ni[S2C2(CF3)2]2(C6H12) (4) have been examined by NiK-edge X-ray absorption near-edge structure (XANES) and extended X-ray absorption fine-structure (EXAFS) spectroscopies. Ni XANES for1–3reveals clear pre-edge features and approximately +0.7 eV shift in the NiK-edge position for `one-electron' oxidation. EXAFS simulation shows that the Ni—S bond distances for1,2and3(2.11–2.16 Å) are within the typical values for square planar complexes and decrease by ∼0.022 Å for each `one-electron' oxidation. The changes in NiK-edge energy positions and Ni—S distances are consistent with the `non-innocent' character of the dithiolene ligand. The Ni—C interactions at ∼3.0 Å are analyzed and the multiple-scattering parameters are also determined, leading to a better simulation for the overall EXAFS spectra. The 1-hexene adduct4presents no pre-edge feature, and its NiK-edge position shifts by −0.8 eV in comparison with its starting dithiolene complex3. Consistently, EXAFS also showed that the Ni—S distances in4elongate by ∼0.046 Å in comparison with3. The evidence confirms that the neutral complex is `reduced' upon addition of olefin, presumably by olefin donating the π-electron density to the LUMO of3as suggested by UV/visible spectroscopy in the literature.

Übergangsmetallkomplexe mit Schwefelliganden, LXXVI Redox- und Additionsreaktionen von Nickelkomplexen mehrzähniger Thioether-Thiolat-Liganden. Röntgenstrukturanalysen von (NMe4)2[Ni(′S2′)2] und [Ni(′S4 – C3′)(PMe3)] / Transition Metal Complexes with Sulfur Ligands, LXXVI Redox and Addition Reactions of Nickel Complexes with Multidentate Thioether-Thiolato Ligands. X-Ray Structure Determinations of (NMe4)2[Ni(′S2′)2] and [Ni(′S4–C3′)(PMe3)]

1991 ◽  
Vol 46 (12) ◽  
pp. 1601-1608 ◽  
Author(s):  
Dieter Sellmann ◽  
Stefan Fünfgelder ◽  
Falk Knoch ◽  
Matthias Moll
Keyword(s):  
Transition Metal ◽  
Metal Complexes ◽  
Structure Analysis ◽  
Transition Metal Complexes ◽  
Nickel Complexes ◽  
Addition Reactions ◽  
Coordination Geometry ◽  
X Ray ◽  
Square Planar ◽  
Structure Determinations

In order to elucidate specific properties of nickel sulfur complexes, redox and addition-elimination reactions of [Ni(′OS4')]2, [Ni(′NHS4')]2, [Ni(′S5')], [Ni('S4—C5')], and [Ni('S4—C3')] were investigated ('OS4′ 2' = 2,2'-bis(2-mercaptophenylthio)diethylether(2—), 'NHS4'2- = 2,2'-bis(2-mercaptophenylthio)diethylamine(2—), 'S5'2- = 2,2'-bis(2-mercaptophenylthio)diethylsulfide(2—), 'S4-C5'2- = 1,5-bis(2-mercaptophenylthio)pentane(2—), 'S4—C3'2- = 1,3-bis(2-mercaptophenylthio)propane(2—)).Cyclovoltammetry proves the complexes to be redox inactive between —1.4 and +0.8 V vs. NHE. Above +0.8 V the complexes are irreversibly oxidized, below —1,4 V desalkylation takes place and [Ni(′S,′)2]2- is formed. An X-ray structure analysis was carried out of (NMe4)2[Ni(′S2')2], which shows a planar anion with the Ni center in a nearly perfect square planar coordination. Distances and angles are practically identical to those in the [Ni(′S2')2-] monoanion.The complexes coordinate only phosphines as coligands, but thioether donors simultaneously decoordinate and, dependant of reaction temperature, mono- or trisphosphine complexes are formed. [Ni(′S4—C3')(PMe3)] was characterized by X-ray structure analysis and exhibits a square pyramidal coordination geometry.

scholarly journals Reaction with Proteins of a Five-Coordinate Platinum(II) Compound

2019 ◽  
Vol 20 (3) ◽  
pp. 520 ◽  
Author(s):  
Giarita Ferraro ◽  
Tiziano Marzo ◽  
Maria Cucciolito ◽  
Francesco Ruffo ◽  
Luigi Messori ◽  
...  
Keyword(s):  
Mass Spectrometry ◽  
Platinum Complexes ◽  
Rnase A ◽  
Side Chain ◽  
Planar Geometry ◽  
Ionization Mass ◽  
X Ray ◽  
X Ray Crystallography ◽  
Egg White Lysozyme ◽  
Square Planar

Stable five-coordinate Pt(II) complexes have been highlighted as a promising and original platform for the development of new cytotoxic drugs. Their interaction with proteins has been scarcely studied. Here, the reactivity of the five-coordinate Pt(II) compound [Pt(I)(Me) (dmphen)(olefin)] (Me = methyl, dmphen = 2,9-dimethyl-1,10-phenanthroline, olefin = dimethylfumarate) with the model proteins hen egg white lysozyme (HEWL) and bovine pancreatic ribonuclease (RNase A) has been investigated by X-ray crystallography and electrospray ionization mass spectrometry. The X-ray structures of the adducts of RNase A and HEWL with [Pt(I)(Me)(dmphen)(olefin)] are not of very high quality, but overall data indicate that, upon reaction with RNase A, the compound coordinates the side chain of His105 upon releasing the iodide ligand, but retains the pentacoordination. On the contrary, upon reaction with HEWL, the trigonal bi-pyramidal Pt geometry is lost, the iodide and the olefin ligands are released, and the metal center coordinates the side chain of His15 probably adopting a nearly square-planar geometry. This work underlines the importance of the combined use of crystallographic and mass spectrometry techniques to characterize, in detail, the protein–metallodrug recognition process. Our findings also suggest that five-coordinate Pt(II) complexes can act either retaining their uncommon structure or functioning as prodrugs, i.e., releasing square-planar platinum complexes as bioactive species.

scholarly journals Metal Complexes of π-Expanded Ligand (7): Syntheses, Structures and Properties of Pt(II) Complexes Containing the Isomeric 1- and 2-Alkyliminomethyl Pyrene Ligands

Crystals ◽  
2020 ◽  
Vol 10 (6) ◽  
pp. 476 ◽  
Author(s):  
Xuan-Dien Luong ◽  
Xuan-Truong Nguyen
Keyword(s):  
Molecular Structure ◽  
Planar Geometry ◽  
X Ray Diffraction ◽  
X Ray ◽  
Pt Complex ◽  
Physico Chemical ◽  
Clear Explanation ◽  
Square Planar ◽  
Structures And Properties ◽  
The Relationship

A [O,N] bidentate π-expanded ligand system, (E)-1-(n-octylimino)methylpyren-2-ol (2), was newly synthesized via a six-step synthesis from pyrene. The ligand 2 reacts with [PtCl2(PhCN)2] in chlorobenzene and the presence of a base at reflux for 2 h under the formation of (2(Pt)) complex with a yield of 70%. The molecular structure of (2(Pt)), studied by common spectroscopic methods and X-ray diffraction, shows a square planar geometry with a trans-configuration of the ligands. The molecular structure, absorption spectra, electrochemical properties, and phosphorescence characteristics of the (2(Pt)) complex are discussed, emphasizing the comparison with those of the previously reported Pt complex (1(Pt)) containing the isomeric ligands of 2, (E)-2-(n-octylimino)methylpyren-1-ol. The DFT calculations of the two Pt complexes are carried out and exhibit a clear explanation of the relationship between their physico-chemical characteristics.

A Xanes Study of Square Copper(II) Complexes

1991 ◽  
Vol 35 (B) ◽  
pp. 1115-1120
Author(s):  
Hisanobu Wakita ◽  
Toshio Yamaguchi ◽  
Hirohiko Adachi ◽  
Manabu Fujiwara ◽  
Seiichi Yamashita
Keyword(s):  
Aqueous Solution ◽  
Lower Energy ◽  
Molecular Orbital Calculations ◽  
Counter Anion ◽  
Edge Structure ◽  
X Ray ◽  
Square Planar ◽  
Tetraaza Macrocycles ◽  
X Ray Absorption ◽  
Back Donation

AbstractThe XANES (X-ray absorption near edge structure) spectra of copper(II) ions in solid state and in solution of the square-planar copper(II) complexes with tetraaza macrocycles were measured. The peaks in the measured XANES spectra shifted to lower energy side with increasing the electron density of central copper(II) ions. The molecular orbital calculations for the complexes were carried out by the DV-Xα method, and the theoretical XANES spectra were estimated. The clear chemical shift obtained by this XANES study is evaluated and leads to a new concept of π-back donation between the copper(II) complexes and counter anion in aqueous solution.

X-ray absorption spectroscopy study of the electronic structure and local coordination of 1st row transition metal-promoted Chevrel-phase sulfides

2019 ◽  
Vol 72 (8) ◽  
pp. 1322-1335 ◽  
Author(s):  
Joseph T. Perryman ◽  
Forrest P. Hyler ◽  
Jessica C. Ortiz-Rodríguez ◽  
Apurva Mehta ◽  
Ambarish R. Kulkarni ◽  
...  
Keyword(s):  
Electronic Structure ◽  
Transition Metal ◽  
Absorption Spectroscopy ◽  
Spectroscopy Study ◽  
X Ray ◽  
Local Coordination ◽  
Chevrel Phase ◽  
X Ray Absorption

An Unusual Cleavage and Macrocyclization in the Zinc-Aqueous Acid Reduction of [2-Methyl-2-Nitro-N,N'-Bis(Pyridin-2-Ylmethyl)-Propane-1,3-Diamine]Coppe R(II) Cation - Crystal-Structure of the (6,13-Dimethyl-1,4,8,11-Tetraazacyclotetradecane-6,13-Diamine)Copper(II) Perchlorate Product

1986 ◽  
Vol 39 (7) ◽  
pp. 1101 ◽  
Author(s):  
GA Lawrance ◽  
BW Skelton ◽  
AH White ◽  
P Comba
Keyword(s):  
Catalytic Reduction ◽  
Electronic Spectroscopy ◽  
Major Product ◽  
Planar Geometry ◽  
X Ray ◽  
Aqueous Acid ◽  
Square Planar ◽  
Spin Resonance ◽  
Unusual Cleavage ◽  
Acid Reduction

Reduction of [2-methyl-2-nitro-N,N?-bis(pyridin-2-ylmethyl)propane- 1,3-diamine]copper(II) with zinc in aqueous hydrochloric acid and subsequent recomplexation yields the macromonocyclic complex (6,13-dimethyl-1,4,8,11-tetraazacyclotetradecane-6,13-diamine)copper(II) perchlorate as the major product, apparently by cleavage of both pyridine rings from the precursor ligand and direct recombination of two saturated residues. Catalytic reduction of the nitro group in the precursor compound can be achieved cleanly over palladium-carbon with hydrogen. The macrocyclic complex crystallized in the space group P21/c, a 8.031(4), b 17.45(1), c 8.436(5) Ǻ, β 117.87(4)°, Z 2; for a single-crystal X-ray structure determination R was 0.078 for 1378 'observed' reflections. The complex is centrosymmetric, the macrocycle having pendant amines on opposite sides of the macrocyclic plane, while perchlorate oxygen atoms occupy the axial sites with Cu-O at 2.59 Ǻ. Observed Cu-N distances of 2.022(6) and 1.996(7) Ǻ are longer than usual for copper(II) amines. Electron spin resonance and electronic spectroscopy define an essentially square-planar geometry in solution, with only weak axial interactions.

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