Pseudotetrahedral Copper Research Articles

Pseudo-tetrahedral copper(II) complex derived from N'-[(2E,3Z)-4-hydroxy-4-phenylbut-3-en-2-ylidene]acetohydrazide: Synthesis, molecular structure, quantum chemical investigations, antioxidant and antiproliferative properties

The mononuclear copper(II) complex involving Schiff base ligand (HL) where HL = (N'-[(2E,3Z)-4-hydroxy-4-phenylbut-3-en-2-ylidene]acetohydraziede) was prepared and characterized by various spectroscopic techniques. The X-ray analysis of this complex revealed that copper(II) was four coordinated by two oxygen atoms (O1 and O2), one nitrogen atom (N1) of the ligand, and one oxygen atom (O3) of the nitrate ligand, forming an unusual pseudo-tetrahedral geometry. The quantum chemical (DFT) calculations evaluated in the study involved the molecular specification for the use of B3LYP/LANL2DZ formalism for copper atom and B3LYP/6-31G for the remaining atoms. The inhibition concentration IC50 and other SOD parameters were calculated. The high antioxidant SOD activity of the complex was discussed and majorly attributed to its distorted geometry based on single crystal X-ray analysis and electronic spectral study. Anticancer activity of the complex was also evaluated by using in vitro validated methods. The complex tested in the present study showed promising antiproliferative properties.

Copper(I) Ethylene Complexes Supported by 1,3,5-Triazapentadienyl Ligands with Electron-Withdrawing Groups

The fluorinated 1,3,5-triazapentadienyl ligands [N{(C3F7)C(2-(NO2)C6H4)N}2]−, [N{(C3F7)C(4-(NO2)C6H4)N}2]−, [N{(C3F7)C(2-(CF3)C6H4)N}2]−, and [N{(C3F7)C(2-F,6-(CF3)C6H3)N}2]− have been used as supporting ligands in copper(I) ethylene chemistry. [N{(C3F7)C(2-(NO2)C6H4)N}2]Cu(C2H4) (7), [N{(C3F7)C(4-(NO2)C6H4)N}2]Cu(C2H4) (8), [N{(C3F7)C(2-(CF3)C6H4)N}2]Cu(C2H4) (9), and [N{(C3F7)C(2-F,6-(CF3)C6H3)N}2]Cu(C2H4) (10) are easily isolable, thermally stable solids and display their ethylene proton and carbon resonances in the δ 3.68–3.48 and 85.2–87.6 ppm regions, respectively. X-ray crystal structures reveal that 7–10 feature trigonal-planar copper sites and κ2-bonded, U-shaped triazapentadienyl ligands. The Cu(I) carbonyl adducts [N{(C3F7)C(2-(NO2)C6H4)N}2]Cu(CO)(NCCH3) (16) and [N{(C3F7)C(4-(NO2)C6H4)N}2]Cu(CO)(NCCH3) (17) have also been synthesized, and they have pseudotetrahedral copper sites. The CO stretching frequencies of the compounds 16 and 17 and ethylene 13C NMR chemical shift data of 7–10 suggest that these molecules have rather acidic copper sites and weakly donating triazapentadienyl ligands.

Preparation and Characterization of Nicotinium Tetrahalocuprate(II) and Tetrahalocobaltate(II) Complexes : Structure of Nicotinium Tetrachlorocobaltate(II)

Nicotine (C10H14N2, nic) is one of the alkaloids well recognized for it's toxin activity, and it's chemistry is an important topic because of its health implications. Nicotine possesses the methylated pyrrolidine nitrogen (pKb1 = 6.16) and the less basic pyridine nitrogen (pKb2 = 10.96), thus it forms a chelate complex resulting in a CuN2X2 chromophore when it reacts with the copper(II) halides. The complex shows a distorted tetrahedral geometry around the copper(II) site (C2v) due to the steric hindrance of the nicotine ligand in the resulting chelate complex. Double protonation of nicotine gives a nicotinium cation, nicH2, which is expected to form easily into crystalline salts with tetrahalometallate(II) anions of the general formula [C10H16N2][MX4]. Recently we reported on the single crystal structure of (nicH2)CuCl4. The crystal exhibited two crystallographically non-equivalent pseudotetrahedral [CuCl4] anions, each of which was linked to two doubly protonated nicotinium cations via hydrogen bonds. The pseudotetrahedral (D2d) geometry around the Cu(II) site in (nicH2)CuCl4 arose from the packing effect caused from the large nicH cation size as well as the strong hydrogen bonding networks between the protonated nicotinium cation and the chloride atoms in [CuCl4]. The pseudotetrahedral copper(II) complexes were interesting in that they were proposed as a mimic compound of active sites in copper proteins. Herein, we investigate the optical and magnetic properties of (nicH2)CuX4 (X=Cl, Br) complexes, and elucidate the observed properties in accordance with the corresponding pseudotetrahedral geometry of the Cu(II) site in the prepared complexes. Furthermore, we synthesize a nicotinium tetrahalocobaltate(II), (nicH2)CoX4 complex. We report on the single crystal structure of the nicotinium tetrachlorocobaltate(II) complex and compare it to that of (nicH2)CuCl4 complex. The optical and magnetic properties of (nicH2)CoCl4 were examined and explained as a symmetric [CoCl4] unit.

Synthesis and Characterization of Pseudotetrahedral Copper(II) Dihalide Complexes with (s)-(-)-Nicotine

and suggested them asmodel compounds for the type I copper(II) site of bluecopper proteins since their physicochemical propertiesmimic interesting spectral and redox behaviors in the bluecopper centers. In the former compound, the copper atomadopted a distorted tetrahedral geometry with a dihedralangle of 68.07

The Structure of the Ligand Tri(1-cyclohepta-2,4,6-trienyl)phosphane, P(C7H7)3, in the Hexafluoroacetylacetonato Copper(I) Complexes, (hfac)Cu[P(C7H7)3]n (n = 1, 2)

Abstract The reaction of CuCl[P(C7H7)3] (1a) with sodium hexafluoroacetylacetonate, Na(hfac), leads to (hfac)Cu[P(C7H7)3] (2a), which in the presence of excess P(C7H7)3 (a) gives (hfac)Cu[P(C7H7)3]2 (3a). Whereas the 1:2 compound 3a is a pseudo-tetrahedral copper(I) complex with relatively long Cu-P (224.85(10) and 223.75(10) pm) and Cu-O (212.7(3) and 212.0(3) pm) distances, the 1:1 complex 2a may be described as having a distorted pseudo-trigonal coordination sphere (Cu-P 214.32(11) pm, Cu-O 196.6(3) and 208.1(3) pm), although one of the cyclohepta-2,4,6-trienyl substituents develops a weak additional interaction with the metal through its central C=C double bond (Cu-C 275.1 and 272.9 pm). The molecular geometries of the tri(1-cyclohepta-2,4,6-trienyl) complexes 2a and 3a are compared with those of the known tri(cyclohexyl)phosphane complexes, (hfac)Cu[P(C6H11)3]n (n = 1 (2b) and 2 (3b)), and related compounds.

Copper(I) Ethylene Adducts and Aziridination Catalysts Based on Fluorinated Tris(pyrazolyl)borates [HB(3-(CF3),5-(R)Pz)3]- (where R = CF3, C6H5, H; Pz = pyrazolyl)

The ethylene adducts of copper(I) tris(pyrazolyl)borates, [HB(3,5-(CF3)2Pz)3]Cu(C2H4), [HB(3-(CF3),5-(C6H5)Pz)3]Cu(C2H4), and [HB(3-(CF3)Pz)3]Cu(C2H4), have been prepared by reacting the corresponding sodium derivative with CF3SO3Cu in the presence of ethylene. They were characterized both in the solid state and in solution using 1H, 13C, and 19F NMR and IR spectroscopy and by X-ray crystallography. Solid samples of these nonionic copper complexes featuring fluorinated tris(pyrazolyl)borate ligands display notably high stability toward air oxidation and ethylene loss. The 1H NMR chemical shifts of the copper(I)-bonded ethylene protons appear in the 4.8−5.2 ppm region. The 13C signal of copper-coordinated ethylene shows an upfield shift of about 35 ppm, whereas the 1JC-H shows a minor change (an increase of about 2−5 Hz) compared to the values for free ethylene. X-ray structural data show the presence of pseudo-tetrahedral copper ions and η2-bonded ethylene units and relatively unperturbed ethylene C−C dis...

Electrochemically and Photochemically Driven Ring Motions in a Disymmetrical Copper [2]-Catenate.

By applying the three-dimensional template effect of copper(I), previously used for making various interlocking ring systems, a new disymmetrical [2]-catenate has been made which consists of two different interlocking rings. One ring contains a 2,9-diphenyl-1,10-phenanthroline (dpp) unit whereas the other cycle incorporates both a dpp motif and a 2,2',6',2''-terpyridine (terpy) fragment, the coordination site of these two chelates pointing toward the inside of the ring. Depending on the oxidation state of the central metal (Cu(I) or Cu(II)), and thus on its preferred coordination number, two distinct situations have been observed. With monovalent copper, the two dpp units interact with the metal and the terpy fragment remains free, at the outside of the molecule. By contrast, when the catenate is complexed to divalent copper, the terpy motif is bonded to the metal and it is now a dpp ligand which lies at the periphery of the complex. This dual coordination mode leads to dramatically different molecular shapes and properties for both forms. The molecular motion which interconverts the four- and the five-coordinate complexes can be triggered chemically, electrochemically, or photochemically by changing the oxidation state of the copper center (II/I). The process has been studied by electrochemistry and by UV-vis spectroscopy. Interestingly, once the stable 4-coordinate copper(I) complex has been oxidized to a thermodynamically unstable pseudo-tetrahedral copper(II) species, the rate of the gliding motion of the rings which will afford the stable 5-coordinate species (copper(II) coordinated to dpp and terpy) can be controlled at will. Under certain experimental conditions, the changeover process is extremely slow (weeks), and the 4-coordinate complex is more or less frozen. By contrast, addition of a coordinating counterion to the medium (Cl-) enormously speeds up the rearrangement and leads to the thermodynamically stable 5-coordinate complex within minutes.

Soluble, well‐defined copper(I) and silver(I) coordination polymers from 4,4″‐bis((9‐aryl)‐2‐o‐phenanthrolinyl)‐2′,5′‐dihexyl‐p‐terphenyl

AbstractA novel synthetic concept is presented which allows, for the first time, the preparation of soluble, constitutionally well‐defined transition‐metal coordination polymers of considerable molecular weights from kinetically unstable, pseudotetrahedral copper(I)‐ and silver(I)‐phenanthroline complexes. It is demonstrated that rigorous exclusion of all molecules that might act as competitive ligands for the metal ions of the polymer constitutes the central requirement for obtaining solutions of “proper” coordination polymers, i.e., polymers having a constant number of repeating units per individual chain. Tetrachloroethane was found to be an appropriate solvent for this purpose. Solubility of the copper(I) and silver(I) coordination polymers – which are polyelectrolytes – in this rather apolar solvent was achieved by the attachment of two hexyl side chains to each polymer repeating unit. It was thus possible to prove the defect‐free constitution of the obtained coordination polymers and to show their excellent stability in solution with the aid of 1H and 13C NMR spectroscopy. Moreover, formation of coordination polymers of considerable chain lengths is supported by the complete disappearance of end‐group absorptions in the 1H NMR spectra and the results of viscosimetric investigations.

Stoichiometric removal of ligand from phosphine-ligated copper(I) reagents with BH 3 · Thf: a novel synthesis of di-μ-bromotetrakis(methyldiphenylphosphine)-dicopper(I) and the structures of CuBr[PMePh 2] 3 and {CuBr [PMePh 2] 2} 2

Attempts to synthesize CuBr[PMePh 2] 2 using standard methods result in the formation of CuBr[PMePh 2] 3 ( I). {CuBr[PMePh 2] 2} 2 ( II) has been conveniently prepared in high yield from I by the reaction with BH 3 · THF in THF, and its molecular structure has been determined. {CuBr[PMePh 2] 2} 2 ( II)crystallizes in the triclinic space group P 1 with cell dimensions a = 10.362(4), b = 10.938(5), c = 12.620(6) Å, α = 74.90(4), β = 67.81(3), γ = 87.91(3)° and Z = 2 (per monomeric unit). The molecule II is a dibromide-bridged dimer with two pseudo-tetrahedral copper atoms. The molecular structure of CuBr[PMePh 2] 3 ( I) is also reported. The species crystallizes in the orthorhombic space group Pna2 1 with Z = 4 and cell constants a = 20.174(7), b = 10.354(3) and c = 17.267(5) Å. The coordination geometry about the copper atom is approximately tetrahedral. Detailed spectroscopic data are reported for both species. This reaction involving removal of phosphines with BH 3 · THF appears to be stoichiometric and general.

A vibronic coupling approach for the interpretation of the g-value temperature dependence in type-I copper proteins

The e.s.r. spectra of copper proteins containing type-I (pseudo-tetrahedral) centres show a gradual decrease of the g‖ values with increasing temperature. This fact is interpreted on the basis of a vibronic coupling mechanism which is effective in pseudo-tetrahedral copper(II) complexes, but not in the square-planar ones. A theory is developed to account for the shift of the g‖ values as well as for the d-d transition energies. A functional role of the vibronic coupling is also suggested.

Characterization of a pseudo-tetrahedral copper(II) complex with two thiolato and two imino donor atoms

Structural characterization of a stable copper(II) complex of a new, sterically constrained tetradentate ligand obtained from 2,2′-bis-(1-phenyl-3-methyl-5-t-butylthiopyrazol-4-ylmethyleneamino)biphenyl containing two imino and two thiolato donor atoms reveals a pseudotetrahedral CuN2S2 co-ordination array with a CuN2–CuS2 dihedral angle of 51.9° and appreciable S ⋯ S interaction; the electronic structure of this compound is related to that of copper centres involving the Cu–S chromophore in copper metalloproteins.

Copper complexes with quadridentate bis(pyrazolyl)thioether amine and tris(pyrazolyl)amine ligands. Structural characterization of the complexes [Cu(NCS)(tpea)][Cu(NCS)2] and [CuCl(bdma)]Cl·2H2O

Copper complexes with the two tripod quadridentate ligands tris(2-pyrazolylethyl)amine (tpea) and bis[2-(3′,5′-dimethylpyrazolyl)ethyl](2-methylthioethyl)amine (bdma) having N4 and N3S donor sets, respectively, have been synthesized and assigned the following formulae: [CuX(tpea)] BPh4(X = Cl, Br, or NCS), [CuCl(tpea)]2[CuCl4], [Cu(NCS)L][Cu(NCS)2](L = tpea or bdma), [Cu(NCS)(bdma)]BPh4·(CH3)2CO, [CuCl(bdma)]Cl·2H2O, and [CuBr(bdma)]3[CuBr3]Br·H2O. The structures of [Cu(NCS)(tpea)][Cu(NCS)2](1) and [CuCl(bdma)]Cl·2H2O (2) have been solved by X-ray diffraction methods. Both compounds crystallize in the monoclinic space group P21/c with Z= 4 and unit-cell dimensions: (1), a=18.026(9), b= 8.847(4), c=16.302(7)A, and β=113.18(5)°; (2),a=17.243(8),b=10.001(5), c=14.763(7)A, and β= 109.52(6)°. The structure of complex (1) consists of isolated [Cu(NCS)(tpea)]+ cations, where the copper(II) atom is in an approximately trigonal-bipyramidal environment of five N atoms, and of layers formed by the [Cu(NCS)2]– anion, with pseudo-tetrahedral copper(I) atoms. The copper(II) atom in the [CuCl(bdma)]+ cation of (2) is in a square-pyramidal environment of one S, one Cl, and three N atoms.

Lewis-base adducts of group 1B metal(I) compounds. Part 13. Crystal structure determinations of tetrakis(triphenylphosphine)-copper(I) and -silver(I) perchlorates, bis(pyridine)bis(triphenyl-phosphine)copper(I) perchlorate, (2,2′-bipyridyl)bis(triphenyl-phosphine)copper(I) perchlorate, and tetrahydroboratobis-(triphenylphosphine)copper(I)–pyridine (1/0.5)

The crystal structures of [Cu(PPh3)4]ClO4(1) and [Ag(PPh3)4]ClO4(2) have been determined by single-crystal X-ray diffraction methods at 295 K, being refined by least-squares methods to residuals of 0.10 and 0.08 for 591 and 1 294 independent ‘observed’ reflections respectively. The two compounds are isomorphous (rhombohedral, space group R, and Z= 2) with a= 19.02(2)Å, α= 44.06(6)° and a= 19.085(5)Å, α= 43.90(1)° respectively; the cation lies on a site of 3 symmetry, while the anion is disordered about a site of symmetry. The metal-atom geometry is pseudo-tetrahedrai [Cu–P = 2.60(1), 2.52(1)Å; Ag–P = 2.650(2)Å, with all P–M–P angles lying between 109.3 and 109.7 °]. For the structure determination of [Cu(PPh3)2(py)2]ClO4(3) obtained by the recrystallization of [Cu(PPh3)4]ClO4 from pyridine (py), 2 843 ‘observed’ reflections were refined to a residual of 0.052. Crystals are triclinic, space group P, with a= 15.599(4), b= 13.413(4), c= 10.982(4)Å, α= 79.51(3), β= 70.47(3), γ= 860.3(3)°, and Z= 2. Cu–P = 2.271(4), 2.295(3)Å and Cu–N = 2.102(7), 2.115(8)Å in a pseudo-tetrahedral copper(I) environment, with P–Cu–P = 115.85(9)° and N–Cu–N = 101.5(2)°. The 2,2′-bipyridyl (bipy) analogue [Cu(PPh3)2(bipy)]ClO4(4) is monoclinic, space group P21/c, with a= 10.210(3), b= 15.085(4), c= 28.455(9)Å, β= 109.13(2)°, and Z= 4. Cu–P = 2.246(3), 2.256(3)Å and Cu–N = 2.056(8), 2.113(9)Å, with P–Cu–P = 125.4(1) and N–Cu–N = 79.6(4)°. R was 0.081 for 2 605 reflections. [Cu(BH4)(PPh3)2], by contrast, yields a hemipyridine solvate, (5), on recrystallization from pyridine; crystals are triclinic, space group P, with a= 12.849(6), b= 10.319(5), c= 13.618(6)Å, α= 102.91(4), β= 101.91(4)γ= 73.42(4)°, and Z= 2. The structure was refined to a residual of 0.051 for 3 633 independent ‘observed’ reflections, and is isomorphous with the hemibenzene solvates of [CuX(PPh3)2](X = Cl or Br) and [AuCl(PPh3)2].

Electron Spin Resonance Study of Pseudotetrahedral Copper(II) and Tetrahedral Cobalt(ll) Complexes

Electron Spin Resonance Study of Pseudotetrahedral Copper(II) and Tetrahedral Cobalt(ll) Complexes

ChemInform Abstract: Xα CALCULATIONS OF THE EPR PARAMETERS OF PSEUDOTETRAHEDRAL COPPER(II) COMPLEXES

Chemischer InformationsdienstVolume 14, Issue 46 Physical Inorganic Chemistry ChemInform Abstract: Xα CALCULATIONS OF THE EPR PARAMETERS OF PSEUDOTETRAHEDRAL COPPER(II) COMPLEXES A. BENCINI, A. BENCINISearch for more papers by this authorD. GATTESCHI, D. GATTESCHISearch for more papers by this author A. BENCINI, A. BENCINISearch for more papers by this authorD. GATTESCHI, D. GATTESCHISearch for more papers by this author First published: November 15, 1983 https://doi.org/10.1002/chin.198346004Read the full textAboutPDF ToolsRequest permissionExport citationAdd to favoritesTrack citation ShareShare Give accessShare full text accessShare full-text accessPlease review our Terms and Conditions of Use and check box below to share full-text version of article.I have read and accept the Wiley Online Library Terms and Conditions of UseShareable LinkUse the link below to share a full-text version of this article with your friends and colleagues. Learn more.Copy URL Share a linkShare onFacebookTwitterLinked InRedditWechat No abstract is available for this article. Volume14, Issue46November 15, 1983 RelatedInformation

X.alpha. calculations of the EPR parameters of pseudotetrahedral copper(II) complexes

ADVERTISEMENT RETURN TO ISSUEPREVArticleNEXTX.alpha. calculations of the EPR parameters of pseudotetrahedral copper(II) complexesAlessandro Bencini and Dante GatteschiCite this: J. Am. Chem. Soc. 1983, 105, 17, 5535–5541Publication Date (Print):August 1, 1983Publication History Published online1 May 2002Published inissue 1 August 1983https://doi.org/10.1021/ja00355a002RIGHTS & PERMISSIONSArticle Views91Altmetric-Citations34LEARN ABOUT THESE METRICSArticle Views are the COUNTER-compliant sum of full text article downloads since November 2008 (both PDF and HTML) across all institutions and individuals. These metrics are regularly updated to reflect usage leading up to the last few days.Citations are the number of other articles citing this article, calculated by Crossref and updated daily. Find more information about Crossref citation counts.The Altmetric Attention Score is a quantitative measure of the attention that a research article has received online. Clicking on the donut icon will load a page at altmetric.com with additional details about the score and the social media presence for the given article. Find more information on the Altmetric Attention Score and how the score is calculated. Share Add toView InAdd Full Text with ReferenceAdd Description ExportRISCitationCitation and abstractCitation and referencesMore Options Share onFacebookTwitterWechatLinked InReddit PDF (796 KB) Get e-Alerts Get e-Alerts

EPR and optical studies in pseudotetrahedral tetramethyl ammonium copper (II) bromide

EPR studies of single crystal copper tetramethyl ammonium bromide, T2CuBr4[T=(CH3)4N] in the temperature range 77–300 K indicate the largest covalency in this compound compared to similar halogenated pseudotetrahedral copper compounds. The angle cos−1γ between the c axis and the ionic g∥ axis is 12° and 65° at 250 and 220 K, respectively. The change is continuous down to 200 K. The g shift between 300 and 200 K indicates an increase in the strength of the ligand field with lowering of temperature. The magnetic susceptibility ellipsoid and the g-tensor ellipsoid do not coincide in this material. Optical spectra in T2(Cu:Zn)Br4 have been assigned. The nonobservation of an EPR signal in T2(Cu:Zn)Br4 and Cs2CuBr4 indicates that ligand field properties in these pseudotetrahedral compounds are quite different from that of T2CuBr4.

Redox comparisons of pseudotetrahedral copper(I) complexes containing tripod ligands

Redox comparisons of pseudotetrahedral copper(I) complexes containing tripod ligands

Relation between structure and spectra of pseudo-tetrahedral copper(II) complexes. Crystal structure of bis(di-2-pyridylamido)copper(II)

The copper(II) complex of the deprotonated form of di-2-pyridylamine has been prepared by treating the ligand with freshly prepared copper(II) hydroxide, and the crystal structure determined. Crystal data: Monoclinic, space group C2/c, a= 14.691(6), b= 12.256(9), c= 11.945(2)A, β= 124.24(3)°, and Z= 4. The final R value was 0.039 for 1 052 independent, observed reflections. The copper atom environment is pseudo-tetrahedral with a dihedral angle of 58.8° between the two CuN2 ligand planes. It is demonstrated that the observed molecular structure and the ligand field spectra in the literature are in good agreement. The extent of distortion from pure tetrahedral geometry in a series of related copper bis(bidentate ligand) complexes, as estimated from ligand-field spectra, correlates very well with the observed crystallographic dihedral angle values. This structural result is now available for calibration of the electronic and e.s.r. spectral data for small-molecule pseudo-tetrahedral copper(II) complexes and the presumed four-co-ordinated Type I ‘blue’ copper protein sites.

The structure of the copper(II) analogue of a pseudotetrahedral copper(I) thioether complex

The structure of the copper(II) analogue of a pseudotetrahedral copper(I) thioether complex