Metal-Mediated Pseudo Coordination Isomerism in Complexes of Mixed Neutral Didentate and Dianionic Tridentate Pyridine-Containing Ligands

2004 ◽  
Vol 57 (6) ◽  
pp. 565 ◽  
Author(s):  
Nathaniel W. Alcock ◽  
Guy J. Clarkson ◽  
Geoffrey A. Lawrance ◽  
Peter Moore
Keyword(s):  
Hydrogen Bonding ◽  
Metal Ion ◽  
Mixed Ligand Complex ◽  
Molar Ratio ◽  
High Yield ◽  
Axial Position ◽  
Water Molecules ◽  
Central Metal ◽  
Ligand Complex ◽  
Space Group

Reaction of nickel(II) or copper(II) acetate with 2-(aminomethyl)pyridine 1 and pyridine-2,6-dicarboxylate ion 2 in aqueous methanol in a 1 : 1 : 1 molar ratio leads to the crystallization in high yield of exclusively one product in each case. For nickel(II), a neutral mixed-ligand complex [Ni · 1 · 2 · (OH2)] is obtained, whereas with copper(II) an ionic complex [Cu · 12 · (OHCH3)][Cu · 22] forms wherein each complex ion contains exclusively one type of ligand. The outcome appears to be directed by the metal ion employed, the two forms being effectively coordination isomers, albeit differing in central metal ion. The neutral complex [Ni · 1 · 2 · (OH2)] · 4¼H2O crystallizes in the triclinic space group P¯1, with two independent nickel centres and ten (some with partial occupancy) water molecules in the asymmetric unit. Each nickel lies in a distorted octahedral environment, with the three N-donor and O-donor sets occupying meridional positions. A complex system of hydrogen bonding and Π-stacking operates in the crystal, with arrays of complex units arranged in ‘dimer tapes’ surrounded by water molecules. The ionic [Cu · 12 · (OHCH3)][Cu · 22] · 2CH3OH complex crystallizes in the monoclinic P21/c space group. The cation adopts a distorted square-based pyramidal geometry with a coordinated methanol in the axial position, although another is weakly interacting in the other axial site. The anion exists in the previously described octahedral geometry with two meridionally-disposed tridentate ligands with the pyridines disposed in trans positions. Three-dimensional ordering in the structure is directed by ‘ribbons’ of hydrogen bonding.

Tris(1,10-phenanthroline-κ2N,N′)iron(II) bis(2,4,5-tricarboxybenzoate) monohydrate and tris(2,2′-bipyridine-κ2N,N′)iron(II) 2,5-dicarboxybenzene-1,4-dicarboxylate–benzene-1,2,4,5-tetracarboxylic acid–water (1/1/2)

2012 ◽  
Vol 68 (9) ◽  
pp. m259-m264 ◽  
Author(s):  
Kai-Long Zhong
Keyword(s):  
Metal Ion ◽  
Mixed Ligand Complex ◽  
Three Dimensional ◽  
Acid Water ◽  
Solvothermal Reaction ◽  
Tetracarboxylic Acid ◽  
Compound I ◽  
Ligand Complex ◽  
Space Group ◽  
Hydrogen Bond Networks

The title compounds, tris(1,10-phenanthroline-κ2N,N′)iron(II) bis(2,4,5-tricarboxybenzoate) monohydrate, [Fe(C12H8N2)3](C10H5O8)2·H2O, (I), and tris(2,2′-bipyridine-κ2N,N′)iron(II) 2,5-dicarboxybenzene-1,4-dicarboxylate–benzene-1,2,4,5-tetracarboxylic acid–water (1/1/2), [Fe(C10H8N2)3](C10H4O8)·C10H6O8·2H2O, (II), were obtained during an attempt to synthesize a mixed-ligand complex of FeIIwith an N-containing ligand and benzene-1,2,4,5-tetracarboxylic acidviaa solvothermal reaction. In both mononuclear complexes, each FeIImetal ion is six-coordinated in a distorted octahedral manner by six N atoms from three chelating 1,10-phenanthroline or 2,2′-bipyridine ligands. In compound (I), the FeIIatom lies on a twofold axis in the space groupC2/c, whereas (II) crystallizes in the space groupP21/n. In both compounds, the uncoordinated carboxylate anions and water molecules are linked by typical O—H...O hydrogen bonds, generating extensive three-dimensional hydrogen-bond networks which surround the cations.

Potentiometric Studies on Stepwise Mixed Ligand Complex Formation

1970 ◽  
Vol 25 (1) ◽  
pp. 22-26 ◽  
Author(s):  
G. Sharma ◽  
J. P. Tandon
Keyword(s):  
Complex Formation ◽  
Metal Ion ◽  
Mixed Ligand Complex ◽  
Iminodiacetic Acid ◽  
Formation Constants ◽  
Ternary Complexes ◽  
Mixed Ligand ◽  
Molar Ratio ◽  
Ligand Complex ◽  
Secondary Ligand

Stepwise mixed ligand complex formation is observed in the systems containing metal ion, iminodiacetic acid (IMDA) as primary ligand and one of the diamines, such as ethylenediamine (en), 1,2-propanediamine (1,2-pn) and 1,3-propanediamine (1,3-pn) as secondary ligands. Potentionmetric titrations indicate the formation of ternary complexes having a 1:1:1 molar ratio of metal ion to iminodiacetic acid to the secondary ligand. Initially, metal-IMDA (1:1) complex is formed in the lower buffer region prior to the formation of the ternary complex and the addition of the secondary ligand takes place only after the combination with the primary ligand is complete. Formation constants (log KMAB) of the ternary complexes have been calculated and the probable reaction mechanism is suggested. The order of stability in terms of metal ion has been found to be Cu (II) > Ni (II) >Zn (II) >Cd (II) and in terms of secondary ligand as 1,2-pn>en>1,3-pn.

Synthesis and Structural Characterization of the Mixed Ligand Complex [Cu(Hml)2(Phen)] · 2 H2O (H2ml = 2-Methyllactic Acid)

2003 ◽  
Vol 58 (1) ◽  
pp. 151-154 ◽  
Author(s):  
Rosa Carballo ◽  
Berta Covelo ◽  
Ezequiel M. Vázquez-Lópeza ◽  
Alfonso Castiñeiras ◽  
Juan Niclós
Keyword(s):  
Magnetic Measurements ◽  
Mixed Ligand Complex ◽  
Three Dimensional ◽  
Mixed Ligand ◽  
Water Molecules ◽  
Ligand Complex ◽  
X Ray ◽  
Dimensional Network ◽  
Distorted Octahedral

Abstract A new mixed-ligand complex of copper(II) with 1,10-phenanthroline and 2-methyllactate was prepared. [Cu(HmL)2(phen)] ·2H2O (where HmL = monodeprotonated 2-methyllactic acid) was characterized by elemental analysis, IR, electronic and EPR spectroscopy, magnetic measurements at room temperature, thermogravimetric analysis and X-ray diffractometry. The copper atom is in a tetragonally distorted octahedral environment and the 2-methyllactato ligand is bidentately chelating. The presence of lattice water molecules mediates the formation of a three-dimensional network.

Transition Metal Squarates, II On the Structure of Cubic (MC4O4·2H2O)3CH3COOH·H2O(M=Zn2+,Ni2+)[1]

1986 ◽  
Vol 41 (11) ◽  
pp. 1329-1332 ◽  
Author(s):  
Armin Weiss ◽  
Eugen Riegler ◽  
Christian Robl
Keyword(s):  
Hydrogen Bonding ◽  
Transition Metal ◽  
Metal Ions ◽  
Water Molecules ◽  
Framework Structure ◽  
Space Group ◽  
3 Dimensional ◽  
Monodentate Ligands ◽  
Oxygen Atoms

Abstract The isotypic compounds (MC4O4·2 H2O)3·CH3COOH·H2O(M=Zn2+,Ni2+) crystallize in the cubic space group Pn3n. The 3-dimensional framework structure contains cavities, which may be filled with CH3COOH · H2O . The metal ions are coordinated almost octahedrally by two water molecules and four oxygen atoms of four C4O42- dianions. Thus the squarate dianions act as fourfold monodentate ligands. Strong hydrogen bonding between H2O and C4O42- has to be assumed.

scholarly journals STRUCTURAL AND SPECTRAL STUDIES OF THE MIXED-LIGAND CATION COMPLEX OF LANTHANUM [Lа(L)2bipy2]BPh4 WITH CARBACYLAMIDOPHOSPHATE (CAPH) TYPE LIGAND AND 2,2'-BIPYRIDINE

2020 ◽  
pp. 15-19
Author(s):  
M. Struhatska ◽  
I. Olyshevets ◽  
V. Dyakonenko ◽  
V. Ovchynnikov ◽  
S. Shishkina ◽  
...  
Keyword(s):  
Mixed Ligand Complex ◽  
Structural Data ◽  
Mixed Ligand ◽  
Molar Ratio ◽  
Spectral Studies ◽  
Ligand Complex ◽  
Absorption Bands ◽  
X Ray ◽  
Phosphoryl Groups ◽  
Oxygen Atoms

A new cationic mixed-ligand complex [Lа(L)2bipy2]BPh4 (where L-= bis(N,N'-diethylamide)(N'-trichloroacetyl)-triamidophosphate anion, bipy = 2,2'-bipyridine) has been synthesized and studied by the means of IR, 1H NMR spectroscopy, thermogravimetric and X-ray structural analyses. Low-frequency shifts of the absorption bands of the carbonyl and phosphoryl groups of phosphorylated ligand in the IR spectra of the complex compared with similar absorption bands in the spectrum of "free" CAPh ligand are Δν(C = O) = 117 cm–1 and Δν(P = O) = 137 cm–1. The analysis of integral signal intensity in the investigated NMR spectra of coordination compounds [Lа(L)2bipy2]BPh4 indicates the molar ratio of ligand : bipyridine : tetraphenylborate anion as a 2:2:1, which corresponds to the proposed structure of the complexes. The compound has been obtained in monocrystalline form. The structure of the complex has been determined by X-ray structural analysis, its ionic structure was proved, and the coordination of two CAPh ligands through the oxygen atoms of the carbonyl and phosphoryl groups was confirmed. Based on the structural data, it was determined that the La3+ ion is octocoordinated (surrounded by four oxygen atoms from two chelated phosphoryl ligands and four nitrogen atoms from two 2,2'-bipyridine molecules). The coordination polyhedron of central ion is interpreted as a square antiprism. Complex cations and tetraphenylborate anions are connected both by electrostatic interaction and by weak intermolecular C – H ∙∙∙ π-contacts between phenyl substituents of BPh4- and molecules of 2,2'-bipyridine. It was established by thermogravimetric analysis that the complex [Lа(L)2bipy2]BPh4 obtained is thermally stable up to a temperature of 150 °C. Significant decomposition of the complex begins at a temperature of 150 °C, occurs in one stage and most intensively continues up to 300 °C. The total weight loss is 78 %.

scholarly journals Development of the method for estimating complex formation using the electrochemical impedance spectroscopy on the example of the doxycycline and iron (III) interaction

2021 ◽  
pp. 31-38
Author(s):  
Anna Dobrova ◽  
Yevhenii Antonenko ◽  
Olga Golovchenko ◽  
Natalia Harna ◽  
Svitlana Garna ◽  
...  
Keyword(s):  
Metal Ion ◽  
Electrochemical Impedance ◽  
Electrochemical Process ◽  
Nyquist Plot ◽  
Molar Ratio ◽  
Medicinal Products ◽  
Doxycycline Hyclate ◽  
Ligand Complex ◽  
Measured Concentration ◽  
Complexation Constant

The aim. To develop an EIS method for study the interaction between medicinal products and metal salts on the example of the Doxycycline and iron (III) interaction. Materials and methods. Measurements of the total impedance of the studied solutions have been performed using a vector circuit analyzer ZNB40 (Rohde & Schwarz, Germany). The calculations of electrical models were performed using the software package EC-Lab V10.40. Measurement cell was made of Teflon, 1 ml of volume, had 2 parallel nickel plated steel electrodes with diameter 6 mm, distance between electrodes is 9 mm. Basic electrical elements of model circuit were calculated according to type of electrochemical process that were described by Nyquist plot (RW, Rct, RS, Cd, CS etc.). Solutions were prepared immediately before the measurement. Measurements were performed at a temperature of 296±3 K. 6 control solutions of doxycycline and 6 control solutions of iron (III) chloride were prepared and measured. 11 study solutions at a molar ratio 1:6, 1:5, 1:4, 1:3, 1:2, 1:1, 2:1, 3:1, 4:1, 5:1, 6:1 were prepared and measured. Concentration of the solutions was X∙10-3 mol/L respectively. Results. EIS analysis of Nyquist curves of study solutions in the range of molar ratios 1: 6, 1: 5, 1: 4, 1: 3, 1: 2, 1: 1, 2: 1, 3: 1, 4: 1, 5: 1, 6: 1 showed a change in the dynamics of electrical resistance at a ratio of 1:1. In the aqueous solution at T = 296±3 K the constant formation of the solution of doxycycline hyclate and iron (III) chloride is 2.9. This value of the complexation constant indicates that doxycycline hyclate forms a stable metal-ligand complex with iron (III) ions. Conclusions. EIS method can be applied to study the interaction of medicinal products. Model of this study was created on the example of doxycycline hyclate and iron (III) chloride. Metal-ion complexation of these two molecules was once again confirmed by using the EIS method

Structure–activity studies of β-carbolines. 1. Molecular structure and conformation of cis-3-carboxylic acid-1,2,3,4-tetrahydroharmane dihydrate

1983 ◽  
Vol 61 (3) ◽  
pp. 529-532 ◽  
Author(s):  
Penelope W. Codding
Keyword(s):  
Molecular Structure ◽  
Crystal Structure ◽  
Hydrogen Bonding ◽  
Carboxylic Acid ◽  
Benzodiazepine Receptor ◽  
Chair Conformation ◽  
Water Molecules ◽  
Space Group ◽  
Structure Activity ◽  
Packing Arrangement

The crystal structure of cis-3-carboxylic acid-1,2,3,4-tetrahydroharmane dihydrate, C13H13N2O2•2H2O, a putative ligand of the benzodiazepine receptor is reported. The space group is P21/c with a = 14.850(4), b = 6.560(3), c = 14.746(4) Å and β = 117.411(8)°, Z = 4. The molecule crystallizes as a zwitterion with the unsaturated ring in a half-chair conformation. Hydrogen bonding to the water molecules included in the lattice determines the molecular packing arrangement.

scholarly journals Synthesis and Spectroscopic and Biological Activities of Zn(II) Porphyrin with Oxygen Donors

2014 ◽  
Vol 2014 ◽  
pp. 1-13 ◽  
Author(s):  
Gauri Devi Bajju ◽  
Sujata Kundan ◽  
Madhulika Bhagat ◽  
Deepmala Gupta ◽  
Ashu Kapahi ◽  
...  
Keyword(s):  
Metal Ion ◽  
Human Cancer ◽  
Biological Activities ◽  
Thermal Studies ◽  
Blue Shift ◽  
Biological Evaluation ◽  
Axial Ligand ◽  
Molar Ratio ◽  
Central Metal

Results of investigation of the physicochemical properties of zinc complexes containing substituted phenols as axial ligand having general formula [X-Zn-t(p-CH3) PP] [where X = different phenolates as axial ligand] in impurity-free organic solvent are presented. The four-coordinated zinc porphyrin accepts one axial ligand in 1 : 1 molar ratio to form five-coordinated complex, which is purified by column chromatography and characterized by physicochemical, biological evaluation and TGA/DTA studies. Absorption spectra show two principal effects: a red shift for phenols bearing substituted electron releasing groups (−CH3, −NH2) and blue shift for phenols bearing electron withdrawing groups (−NO2, −Cl) relative to Zn-t(p-CH3) PP, respectively.1H NMR spectra show that the protons of the phenol ring axially attached to the central metal ion are merged with the protons of the porphyrin ring. Fluorescence spectra show two fluorescence peaks in the red region with emission ranging from 550 nm to 700 nm. IR spectra confirm the appearance of Zn-NPorand Zn-O vibrational frequencies, respectively. According to the thermal studies, the complexes have a higher thermal stability and the decomposition temperature of these complexes depends on the axial ligation. The respective complexes of X-ZnII-t(p-CH3) PP were found to possess higher antifungal activity (up to 90%) and higherin vitrocytotoxicity against human cancer cells lines.

Crystal Structures of (3S*,4S*,5S*,6S*)-3,4-Epoxy- 1,7-dioxaspiro[5.5]undecan-5-ol, (3R*,5S*,6S*)-1,7- Dioxaspiro[5.5]undecane-3,5-diyl Diacetate and (4S*,5S*,6S*)-1,7-Dioxaspiro[5.5]undecane-4,5-diol

1997 ◽  
Vol 50 (2) ◽  
pp. 123
Author(s):  
Margaret A. Brimble ◽  
Andrew Johnston ◽  
Trevor W. Hambley ◽  
Peter Turner
Keyword(s):  
Hydrogen Bonding ◽  
Hydroxy Group ◽  
Axial Position ◽  
Monoclinic Space Group ◽  
Equatorial Position ◽  
Intermolecular Hydrogen Bonding ◽  
Orthorhombic Space Group ◽  
Triclinic Space Group ◽  
Space Group ◽  
X Ray Crystallography

The structures of (3S*,4S*,5S*,6S*)-3,4-epoxy-1,7-dioxaspiro[5.5]undecan-5-ol (2), (3R*,5S*,6S*)-1,7- dioxaspiro[5.5]undecane-3,5-diyl diacetate (4) and (4S*,5S*,6S*)-1,7-dioxaspiro[5.5]undecane-4,5-diol (5) have been determined by X-ray crystallography. The unsubstituted tetrahydropyran ring in (2) adopts an axial position with respect to the epoxy-substituted ring and the hydroxy group at C5 is syn to the epoxide group. Intermolecular hydrogen bonding is observed between the C5 hydroxy group and O1. The two six-membered rings in (4) adopt chair conformations and the two acetate groups adopt 1,3-diaxial positions. The C5 hydroxy group in (5) assumes an axial position anti to the C-O bond of the neighbouring ring whilst 4-OH occupies an equatorial position. Intermolecular hydrogen bonding is also observed between 4-OH and 5-OH. Compound (2), C9H14O4, M 186·21, crystallized in the monoclinic space group P 21/c with a 7·867(1), b 12·2060(9), c 9·3676(8) Å, b 102·744(8), V 877·4(1) Å 3 and No 1163 [I > 2·5s (I)], R 0·031, Rw 0·035. Compound (4), C13H20O6, M 272·30, crystallized in the triclinic space group P 1 with a 9·902(1), b 11·0024(9), c 6·9183(5)Å, a 104·078(8), b 96·769(9), g 101·980(8), V 703·8(1) Å 3 , No 1657 [I > 2·5s(I)], R 0·047, Rw 0·044. Compound (5), C9H16O4, M 188·22, crystallized in the orthorhombic space group Pbca with a 25·504(3), b 8·909(2), c 8·038(2) Å, V 1826·4(5) QA 3 , No 1096 [I > 2·5s(I)], R 0·030, Rw 0·030.

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