Structural Studies of the Template Effect: Formation of Macrocyclic Ligands Incorporating Heavy Donor Atoms

1988 ◽  
Vol 41 (2) ◽  
pp. 159 ◽  
Author(s):  
JM Harrowfield ◽  
JM Patrick ◽  
BW Skelton ◽  
AH White
Keyword(s):  
Metal Ion ◽  
Bidentate Ligand ◽  
Structural Studies ◽  
Donor Atom ◽  
Donor Ligand ◽  
X Ray ◽  
Racemic Form ◽  
Square Planar ◽  
Template Reaction ◽  
Sulfur Donor

X-ray structural studies of both products and reactants involved in the template formation of the macrocycle 'cyclars' (5,14-dimethyl-5,6- 7,9,14,15,16,18-octahydrodibenzo[e,l]- dithiadiarsacyclotetradecin ) have been performed, and the results used to define several aspects of possible reaction mechanisms. The structure of the racemic form of cyclars shows that this free arsenic/sulfur donor ligand is not 'preorganised' for square-planar coordination, though metal ion/donor atom distances in its palladium(II) complex (Pd-As 2.388 Ǻ, Pd-S 2.314 Ǻ) do appear normal. In contrast, the structure of the palladium(II) complex of the arsenic meso ligand, which is not a direct product of the template reaction, shows relatively short palladium/donor atom distances (Pd-As 2.361 Ǻ, Pd-S 2.278 Ǻ), suggesting that template formation may be inhibited because the 'hole size' of this ligand diastereomer is too small for palladium(II). Further, the structure of a bis (bidentate) ligand precursor complex which could, in principle, generate the meso macrocycle shows that, in the solid at least, the reactant groups are not favourably juxtaposed for cyclization. The structure of the platinum(II) complex of a sulfenate derivative of the same bidentate ligand suggests that electrophili c attack at coordinated thiolate, the crucial step in the macrocycle formation, is completely unselective for an unconstrained electrophile.

scholarly journals Synthesis and Spectroscopic Characterization for Some Metal ion Complexes with 2-Hydroxy-3-((5-Mercapto-1,3,4-Thiadiazol-2-yl)Diazenyl)-1-Naphthaldehyde

2016 ◽  
Vol 13 (2) ◽  
pp. 105-114
Author(s):  
Baghdad Science Journal
Keyword(s):  
Metal Complexes ◽  
Metal Ion ◽  
Mass Spectra ◽  
Spectroscopic Characterization ◽  
Bidentate Ligand ◽  
Molar Ratio ◽  
Theoretical Treatment ◽  
Spectroscopic Techniques ◽  
Metal Ion Complexes ◽  
Square Planar

New metal ion complexes were synthesized with the general formula; K[PtLCl4], [ReLCl4] and K[ML(Cl)2] where M = Pd(II), Cd(II), Zn(II) and Hg(II), from the Azo ligand (HL) [2-Hydroxy-3-((5-mercapto-1,3,4-thiadiazol-2-yl)diazenyl)-1-naphth aldehyde] (HL) the ligand was synthesized from (2-hydroxy-1-naphthaldehyde) and (5-amino-1,3,4-thiadiazole-2-thiol). The ligand and its metal complexes are characterized by phisco- chemical spectroscopic techniques (FT.IR, UV-Vis and Mass spectra, elemental analysis, molar conductivity, Atomic Absorption, Chloride contain and magnetic susceptibility). The spectral data suggest that the (HL) behaves as a bidentate ligand in all complexes. These studies revealed tetrahedral geometries for all metal complexes, except square planar for Pd(II) complex and except octahedral geometry for Pt(IV) and Re(V) complexes. The study of complexes formation via molar ratio of (M:L) as (1:1). Theoretical treatment of this ligand and its metal complexes in gas phase using Hyper chem.8 was preformed.

Synthetic and structural studies on metal complexes of tripyrrin

2003 ◽  
Vol 07 (01) ◽  
pp. 17-24 ◽  
Author(s):  
Martin Bröring ◽  
Carsten D. Brandt ◽  
Serguei Prikhodovski
Keyword(s):  
Transition Metal ◽  
Metal Complexes ◽  
Metal Ion ◽  
Coordination Geometry ◽  
Structural Studies ◽  
Structural Investigations ◽  
Coordination Polyhedra ◽  
X Ray ◽  
Step Procedure ◽  
Porphyrin Analogues

A general two-step procedure for the synthesis of metallotripyrrinates TrpyMOAc f with M = Co(II) , Cu(II) , Zn(II) and Pd(II) , and OAc f = trifluoroacetate, is described, starting from well-known monopyrrolic precursors and simple transition metal acetates. X-ray structural investigations were undertaken on four different complexes, and the results reveal, that the nature of the metal ion, rather than the ligand, determines the coordination geometry of these porphyrin fragment complexes. The finding of pseudotetrahedral and strained pseudoplanar coordination polyhedra at the metal centres makes a clear distinction between metalloporphyrins and metallotripyrrins and shows the latter to be related to some recently discovered metal chelates of macrocyclic porphyrin analogues.

Synthesis, spectroscopic characterization, X-ray structure, and in vitro antitumor activities of new triorganotin(IV) complexes with sulfur donor ligand

2013 ◽  
Vol 22 (12) ◽  
pp. 5730-5738 ◽  
Author(s):  
Mojdeh Safari ◽  
Mohammad Yousefi ◽  
Hilary A. Jenkins ◽  
Maryam Bikhof Torbati ◽  
Amir Amanzadeh
Keyword(s):  
Spectroscopic Characterization ◽  
Antitumor Activities ◽  
Donor Ligand ◽  
X Ray ◽  
Sulfur Donor

Übergangsmetallkomplexe mit Schwefelliganden, LXXV / Transition Metal Complexes with Sulfur Ligands, LXXV

1991 ◽  
Vol 46 (12) ◽  
pp. 1593-1600 ◽  
Author(s):  
Dieter Sellmann ◽  
Stefan Fünfgelder ◽  
Falk Knoch
Keyword(s):  
Reaction Mechanism ◽  
Transition Metal Complexes ◽  
Coordination Geometry ◽  
Chain Reaction ◽  
Radical Chain ◽  
X Ray ◽  
Square Planar ◽  
Product Forms ◽  
Radical Chain Reaction ◽  
Template Reaction

[Ni(′NHS′4)]2 (′NHS′42- = 2,2′-bis(2-mercaptophenylthio)diethylamine(2-)) was synthesized from Ni(ac)2 and Na2—′NHS′4 and characterized by X-ray structure analysis. In the solid state [Ni(′NHS′4)]2 contains two pseudooctahedral [Ni(′NHS′4)] fragments bridged via thiolate donors, in DMF solution at 110 °C it dissociates into mononuclear entities. The product of the template reaction between [Ni(′S′2)2]2- (′S′22- = 1,2-benzenedithiolate) and (BrC2H4)2NH was shown to contain an as yet unidentified by-product in addition to [Ni(′NHS′4)]2. Pure [Ni(′NHS′4)]2 does not react with pyridine, but the template product forms [Ni(Py)2(′S′2)] which has a square planar coordination geometry with the pyridine rings perpendicular to the NiS2N, plane.Investigation of the template formation of [Ni(′NHS′4)]2 provided evidence that the reaction of [Ni(′S′2)2]2- with (BrC2H4)2NH involves radicals, suggesting a radical chain reaction mechanism.

Characterization of the adducts of bis(O-isoamyldithiocarbonato) nickel(II) with heterocyclic amines and X-ray structure of bis(O-isoamyldithiocarbonato)-bis(3-bromopyridine)nickel(II)

2016 ◽  
Vol 57 (8) ◽  
pp. 1688
Keyword(s):  
Magnetic Susceptibility ◽  
Spectral Data ◽  
Metal Ion ◽  
Diffraction Method ◽  
Bidentate Ligand ◽  
X Ray Diffraction ◽  
X Ray ◽  
Cell Parameters ◽  
Infrared Spectral ◽  
Substituted Pyridines

A series of six-coordinated Ni(II) complexes, with the general formula Ni(Xan)L2 (where Xan = isoamyldithiocarbonato and L = 2-bromopyridine, 3-bromopyridine, 4-acetylpyridine, 3-hydroxypyridine and 2-methoxypyridine) are synthesized and characterized by the elemental analysis and various physicochemical techniques such as magnetic susceptibility and conductivity measurements, UV-visible and infrared spectral data. Based on the electronic spectra and magnetic susceptibility measurements, an octahedral geometry is proposed for all the complexes. IR spectral data show that in all these complexes substituted pyridines coordinate to the metal ion through nitrogen atoms occupying the fifth and sixth axial positions, whereas O-alkyldithiocarbonate acts as a monoanion bidentate ligand and occupies the planar positions of octahedral structures. The structure of the adduct with 3-bromopyridine is elucidated by the single crystal X-ray diffraction method. The complex crystallizes in the triclinic space group P-1 with unit cell parameters a = 6.5855(4) Å, b = 9.4984(6) Å, c = 12.4518(8) Å, α = 87.944(5)°, β = 78.843(5)°, γ = 77.794(5)°. The crystal structure of the molecule is stabilized by intermolecular C—H…S and C—H…π interactions.

Octahedral Complexes of a Mixed N,N,O-Donor Ligand N-trans-(2'-hydroxycyclohexyl)-2-aminomethylpyridine

2004 ◽  
Vol 57 (5) ◽  
pp. 483 ◽  
Author(s):  
Mark J. Robertson ◽  
Geoffrey A. Lawrance ◽  
Marcel Maeder ◽  
Peter Turner
Keyword(s):  
Complex Cation ◽  
Monoclinic Space Group ◽  
Cyclohexene Oxide ◽  
Donor Ligand ◽  
X Ray ◽  
Single Isomer ◽  
Square Planar ◽  
Bonding Interaction ◽  
Distorted Octahedral ◽  
Jahn Teller

The unsymmetric mixed-donor Nam,Npy,O-ligand N-trans-(2'-hydroxycyclohexyl)-2-aminomethylpyridine (pyca, 1) was readily prepared by reaction of an epoxide (cyclohexene oxide) with (2-aminomethyl)pyridine. The ligand forms octahedral bis-tridentate complexes, exemplified with isolation of copper(II), nickel(II), zinc(II), and cobalt(III) compounds; in addition, a square-planar palladium(II) complex with the ligand behaving as bidentate was prepared. The bis-tridentate octahedral complexes may exist in six geometric isomeric forms, and molecular mechanics analysis was employed to predict the most stable isomer for copper(II), nickel(II), and cobalt(III) complexes. For the copper(II) and cobalt(III) complexes, the predictions match the X-ray crystal structures of the single isomer isolated in each case. Both the copper(II) complex [Cu . 12](ClO4)2 and the cobalt(III) complex [Co . 1 . (1–H)](ClO4)2 crystallized in the monoclinic space group P21/n (no. 14), with a 9.8400(13), b 15.434(2), c 10.0180(13) Å, and β 109.004(2)°, and a 14.162, b 18.583, c 21.596 Å, and β 100.04°, respectively. Both complexes adopt distorted octahedral structures. The copper(II) complex exists as the all-trans-fac isomer with Jahn–Teller elongation of the Cu–O bond [2.3795(19) Å] compared to Cu–Npy [2.040(2) Å] and Cu–Nam [2.024(2) Å] distances. The cobalt(III) complex appears as the cis,cis,trans(Npy) fac isomer, but deprotonation of one of the two alcohol groups leads to all six M–L distances differing: for each of two similar independent complex cations, Co–O [e.g. 1.9123(16), 1.9459(16) Å], Co–Nam [e.g. 1.949(2), 1.968(2) Å], and Co–Npy [e.g. 1.938(2), 1.940(2) Å] vary, with particularly the deprotonated alcohol bond significantly shorter than the protonated bond, despite a strong hydrogen bonding interaction with the protonated alcohol in the partner complex cation in the unit cell.

Synthetic and Structural Studies of Binuclear Organopalladium(II) Complexes Including a Bis(pyridin-2-yl)phenylmethyl Complex With Four- and Eight-Membered Palladocycle Rings, trans(N,N)-(Pd(μ-Py2PhC-N,N',C')Cl)2.½CH2Cl2.½Me2CO

1988 ◽  
Vol 41 (5) ◽  
pp. 651 ◽  
Author(s):  
AJ Canty ◽  
NJ Minchin ◽  
LM Engelhardt ◽  
BW Skelton ◽  
AH White
Keyword(s):  
Ethyl Acetate ◽  
Column Chromatography ◽  
Isolation Procedure ◽  
Addition Reactions ◽  
Structural Studies ◽  
Monoclinic System ◽  
Space Group ◽  
X Ray ◽  
Square Planar ◽  
System 2

The byridin-2-yl) phenylchloromethanes PyPh2CCl and Py2PhCCl undergo oxidative addition reactions with bis ( dibenzylideneacetone )palladium(0) to form {Pd(PyPh2C) Cl }2 (1) and {Pd(Py2PhC)C}2.�2CH2Cl2.�Me2CO (2), respectively. n.m.r , studies of (1) in CDCl3 indicate presence of an equilibrium between two isomers, involving the ligand (pyridin-2-yl ) diphenylmethyl in η3-coordination, {Pd(η3-PyPh2C)(μ- Cl )}2. Complex (2) has two bis (pyridin-2-yl) phenylmethyl groups present as bridging N,C′- ligands , with the groups also N,C- bidentate to each palladium, to form a binuclear compex containing four- and eight- membered palladocycles: PdC(CN)CNPdC(CN)CNBoth palladium(II) centres in (2) have square-planar 'trans-PdCN2Cl' coordination, so that (2) may be represented as trans(N,N)-{Pd(μ- Py2PhC-N,N′, C′) Cl }2.�CH2Cl2.�Me2CO. A complex similar to (2), trans(N,N)-{Pd(μ- PyPhCH -N,C?)( γmpy ) Cl }2.CH2Cl2 (3), forms on reaction of the lithium derivative of 2-benzylpyridine, Li( PyPhCH ), with dichlorobis (4-methylpyridine)palladium(II); (3) reacts with excess 2-benzylpyridine with displacement of γmpy to form trans(N,N)-{Pd(μ- PyPhCH -N,C?)(PyPhCH2) Cl }2 (4). In developing an alternative isolation procedure for (3), involving column chromatography with 4% ethyl acetate in chloroform, the coordination complex trans- bis{1-phenyl-1-(pyridin-2-yl)prop-1-en-2-olato-O,N}palladium(II), Pd{( PyPhC )C(Me)O}2 (5), was isolated in low yield. X-Ray structural studies of (2)-(5) have been completed, with all four complexes crystallizing in the monoclinic system; (2): space group P21/c, a 9.649(6), b 21.116(9), c 18.627(7)Ǻ,β 111.42(4)°, Z 4; (3): P21/c, a 13.967(2), b 13.996(3), c 18.886(2)Ǻ, β 98.74(1)°, Z 4; (4): P21/n, a 14.274(9), b 14.584(14), c 20.97(2)Ǻ, β 109.18(5)°, Z 4; (5): P21/c, a 15.184(3), b 7.887(6), c 19.240(2)Ǻ, β 97.51(1)°, Z 4.

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