Fluorinated Alkoxides. Part VIII. Mixed Ligand Complexes of Perfluoropinacol with Ni2+, Pd2+, Pt2+ and Cu2+. Solvation Equilibria between 4- and 5-coordinate Ni2+

1975 ◽  
Vol 53 (6) ◽  
pp. 809-816 ◽  
Author(s):  
W. Stafford Cripps ◽  
Christopher J. Willis
Keyword(s):  
Metal Ion ◽  
Nickel Complexes ◽  
Mixed Ligand ◽  
Ligand Field ◽  
Electronic Effects ◽  
Unusual Behavior ◽  
Planar Structures ◽  
Square Planar ◽  
Phosphorus Containing ◽  
Fluorinated Alkoxides

Perfluoropinacol, (CF3)2C(OH)C(OH)(CF3)2, ionizes by loss of two protons, and the resulting dinegative ion (PFP2−) chelates to Ni2+, Pd2+, Pt2+, and Cu2+. A variety of stable neutral complexes may be isolated if the tetracoordination of the metal ion is completed with two monodentate or one bidentate nitrogen- or phosphorus-containing ligands; square-planar structures are invariably found. The structures of these complexes are contrasted with those of analogous halides, and it is concluded that electronic effects are predominant in determining them, although steric influences may sometimes be important. The ligand field strength of the perfluoropinacolato ion is approximately equal to that of the thiocyanate ion.The nickel complexes Ni(PFP)22− and (PFP)Ni(RNHCH2CH2NHR) react with donor solvents (water, methanol, pyridine, etc.) to give equilibria between four- and five-coordinate solvated species; six-coordinate species are not observed. This unusual behavior is attributed to the steric hindrance imposed by the bulk of the PFP2− ligand.

Nickel complexes of ligands derived from (o-hydroxyphenyl) dichalcogenide: delocalised redox states of nickel and o-chalcogenophenolate ligands

2019 ◽  
Vol 48 (46) ◽  
pp. 17355-17363 ◽  
Author(s):  
Sridhar Banerjee ◽  
Debobrata Sheet ◽  
Subhash Sarkar ◽  
Partha Halder ◽  
Tapan Kanti Paine
Keyword(s):  
Metal Ion ◽  
Nickel Complexes ◽  
Redox States ◽  
Square Planar

The monoanionic square planar S = 1/2 nickel complexes of dianionic o-chalcogenophenolate ligands display delocalised redox states of the metal ion and ligands.

Cobalt(II), nickel(II) and copper(II) complexes of some 2'-hydroxychalcones

1980 ◽  
Vol 33 (4) ◽  
pp. 737 ◽  
Author(s):  
M Palaniandavar ◽  
C Natarajan
Keyword(s):  
Infrared Spectra ◽  
Metal Ion ◽  
Magnetic Moments ◽  
Phenyl Group ◽  
Ligand Field ◽  
Square Planar ◽  
Spin Pairing ◽  
Square Configuration ◽  
Electron Sink ◽  
Octahedral Configuration

Metal(II) bis-chelates of the type ML2 [M = CoII, NiII, CuII; L = 2'- hydroxy-5'-X-chalcone where X = H, CH3, Cl] have been prepared and studied. Structures have been assessed by the measurement of magnetic moments, ligand field and infrared spectra and thermal properties. These chelates possess low-spin trans-square-planar configuration and show resistance to adduct formation in contrast to metal(II) chelates of β-diketones, salicylaldehyde, o-hydroxyaryl ketones and esters and o-hydroxy-crotonophenones, which have high-spin octahedral configuration. Extensive conjugation lowers the energy of the π3* orbital which enters into a very strong dπ-π3* interaction leading to spin-pairing. ��� Infrared spectra indicate that the carbonyl group is perturbed only slightly by coordination to metal. A change in metal ion affects v(C=O), v(M-O) and other vibrations and the order of stability, namely, Co ≈ Ni < Cu, inferred from these vibrations is as expected for the low-spin square configuration of the chelates. Introduction of substituents (5'-X) alters only v(M-O) significantly and the order of stability, namely, Cl > CH3 > H, derived from v(M-O) is consistent with Taft's resonance polar parameters of the substituents. All these observations are explained by the electron sink property of the phenyl group.

Copper(II) complexes of o-hydroxyarylcarbonyl compounds

1968 ◽  
Vol 21 (3) ◽  
pp. 617 ◽  
Author(s):  
DP Graddon ◽  
GM Mockler
Keyword(s):  
Solid State ◽  
Chelate Ring ◽  
Magnetic Moments ◽  
Equilibrium Constants ◽  
Ligand Field ◽  
Infrared Band ◽  
Planar Structures ◽  
Square Planar ◽  
Inductive Effects ◽  
Ligand Field Spectra

A series of copper(11) complexes has been prepared of the type CuL2Bn, where L is an o-hydroxy-aryl-, or naphthyl-, aldehyde, ketone, or ester, B is water or 4-methylpyridine, and n = 0, 1, or 2. All these complexes have a strong infrared band in the region 1600-1660 cm-l, showing that the oxygen atoms in the chelate ring are non-equivalent ; their magnetic moments fall in the range usual for copper(11) compounds. Equilibrium constants determined for the addition of one molecule of 4-methylpyridine to the anhydrous compounds in chloroform solutions fall in the range 0.5 < k < 40 and are comparable to the constant for the addition of 4-methylpyridine to bis(acetylacetonato)copper(11) (b 2.7). Increased stability of the adducts can be associated with the inductive effects of ligand substituents. Ligand field spectra in the solid state and in solution closely resemble those of corresponding bis(acetylaoetonato)copper(11) complexes and provide evidence for square-planar structures of the anhydrous complexes and square-pyramidal structures of the 1 : 1 adducts with 4-methylpyridine or water. No evidence is available for the structures of 1 : 2 adduots which may be formed in solutions in 4-methylpyridine; these solutions are unstable, but the nature of the slow reactions which occur in these solutions is not known.

Fluorinated alkoxides. Part X. Template syntheses leading to fluorinated β-imino-alkoxy complexes of four- and five-coordinate nickel(I1) and copper(I1)

1977 ◽  
Vol 55 (13) ◽  
pp. 2459-2464 ◽  
Author(s):  
John W. L. Martin ◽  
Christopher J. Willis
Keyword(s):  
Metal Ions ◽  
Metal Ion ◽  
Condensation Reactions ◽  
Template Condensation ◽  
Square Planar ◽  
Fluorinated Alkoxides

Hexafluorodiacetonealcohol, HFDA, HOC(CF3)2CH2COCH3, is sufficiently acidic to coordinate to metal ions in an ionized form as a chelating, uninegative ligand. Complexes of Ni2 + and Cu2+ may be isolated, most conveniently by using a tridentate nitrogen-containing macrocycle as co-ligand so that five-coordinate unipositive compounds are produced. In the presence of metal ions, HFDA readily undergoes template condensation reactions with diamino-ethane or -propane to give conplexes of ionized β-imino alcohols, e.g. -OC(CF3)2- CH2C(CH3) : N(CH2)2N : C(CH3)CH2C(CF3)20- ; these conplexes are neutral and square planar but become five-coordinate by solvation in, e.g., pyridine. The use of triamines H2N- (CH2),NH(CH2).NH2 (where n = 2 or 3) in template syntheses with HFDA gives complexes in which the metal ion is five-coordinate; these do not undergo solvation.

Cobalt(II), nickel(II) and copper(II) complexes of some o-hydroxycrotonophenones

1980 ◽  
Vol 33 (4) ◽  
pp. 729 ◽  
Author(s):  
M Palaniandavar ◽  
C Natarajan
Keyword(s):  
High Spin ◽  
Metal Ion ◽  
Magnetic Measurements ◽  
Thermal Studies ◽  
Ligand Field ◽  
Square Planar ◽  
Infrared Studies ◽  
Stabilization Energies ◽  
Back Bonding ◽  
High Ligand

Metal(II) complexes of the type ML2,nB [M = CuII, NiII, CoII; L = 2- hydroxy-5-X-crotonophenone where X = H, CH3, Cl; B = H2O, pyridine; n = 0, 1, 2] have been obtained and investigated. With the help of element analyses, magnetic measurements, ligand field and infrared spectra and thermal studies, the structure and the nature of bonding have been established. The anhydrous copper(II) chelates are monomeric and possess trans-square-planar configuration while the corresponding cobalt(II) and nickel(II) compounds are polymeric and possess high-spin trans-octahedral configuration. All the base adducts possess high-spin trans-octahedral structure with lesser tendency toward dissociation in solution. Infrared studies indicate that v(C=O) and v(M-O) are affected by metal ion and phenyl substitutions and adduct formation. The order of stabilities, namely Cu > Ni > Co, derived from v(M-O) parallels the crystal field stabilization energies. Substitution in the phenyl ring of the complexes produces shifts in v(M-O) which are related to the resonance capacities of the substituents. ��� The relatively high ligand field strength of o-hydroxycrotonophenone compared to salicylaldehyde is attributed to the conjugation of C=O with C=C which lowers the energy of the π3* orbital leading to extensive back-bonding with dπ orbitals of the metal.

Fully Fluorinated Alkoxides. Part VI. Derivatives of Hydroxyhexafluoroisobutyric Acid

1972 ◽  
Vol 50 (6) ◽  
pp. 939-945 ◽  
Author(s):  
J. T. Price ◽  
A. J. Tomlinson ◽  
C. J. Willis
Keyword(s):  
Mixed Ligand ◽  
Mixed Ligand Complexes ◽  
Tridentate Ligand ◽  
Phosphorus Containing ◽  
Fluorinated Alkoxides ◽  
Derivatives Of ◽  
Spectrochemical Series

Hydroxyhexafluoroisobutyric acid, HOC(CF3)2COOH, H2(HHIB), gives complexes with a variety of metals, acting as a chelating, dinegative ligand. Derivatives prepared include [B(HHIB)2]−, [M(HHIB)2]2− (M = Ni, Cu, Co), [M(HHIB)3]3− (M = Al, Cr, Mn, Fe), and mixed ligand complexes of Cu and Ni with HHIB and nitrogen- or phosphorus-containing ligands. In some cases, the HHIB anion appears to act as a tridentate ligand through carboxylate bridging. HHIB is close to water in the spectrochemical series.

Complexes of substituted benzothiazoles 4. Nickel(II) complexes of the bidentate benzothiazoles 1,2-bis(2-benzothiazolyl)benzene and 1,2-bis(2-benzothiazolyl)ethane

1982 ◽  
Vol 60 (4) ◽  
pp. 514-520 ◽  
Author(s):  
Laurence Kenneth Thompson ◽  
John Charles Thomas Rendell ◽  
George Charles Wellon
Keyword(s):  
Coordination Chemistry ◽  
Infrared Spectra ◽  
Nickel Complexes ◽  
Magnetic Data ◽  
Octahedral Complex ◽  
Ligand Field ◽  
Tetrahedral Coordination ◽  
Ethylene Bridge ◽  
X Ray ◽  
Square Planar

The nickel coordination chemistry of two potentially bidentate bis-benzothiazole ligands is compared. 1,2-Bis(2-benzothiazolyl)-benzene (OBT), which has an o-phenylene bridge, forms square planar derivatives with NiX2 (X = I, ClO4, BF4), octahedral derivatives with NiX2 (X = NCS, NO3), and five-coordinate derivatives with NiX2 (X = CI, Br). 1,2-Bis(2-benzothiazolyl)ethane (BBTE), which has an ethylene bridge, forms tetrahedral derivatives with NiX2 (X = CI, Br, I) and an octahedral complex with Ni(NO3)2. Although both ligands are capable of tetrahedral coordination about a cobalt centre, the apparent preference of tetrahedral coordination with nickel complexes of BBTE seems unusual. The only difference between the two ligands lies in the bridging group between the benzothiazole rings. Structural assignments are supported by ligand field and infrared spectra, magnetic data, and an X-ray structure of the complex [Ni(BBTE)Br2], which has been shown to have a distorted tetrahedral stereochemistry.

scholarly journals The First Metal Complexes of 4,6-diamino-1-hydro-5-hydroxy-pyrimidine-2-thione: Preparation, Physical and Spectroscopic Studies, and Preliminary Antimicrobial Properties

2008 ◽  
Vol 2008 ◽  
pp. 1-8 ◽  
Author(s):  
Sahar I. Mostafa ◽  
Constantina Papatriantafyllopoulou ◽  
Spyros P. Perlepes ◽  
Nick Hadjiliadis
Keyword(s):  
Metal Ion ◽  
Room Temperature ◽  
Free Ligand ◽  
Antimicrobial Properties ◽  
Spectroscopic Studies ◽  
Ligand Field ◽  
Square Planar ◽  
Elemental Analyses ◽  
Bidentate Chelate

The new complexes[M2O5L2(H2O)2]⋅H2O (M=Mo,1;M=W,2),[RuL2(H2O)2]⋅H2O (3),[ML3]⋅xH2O (M=Rh,x=2,4;M=Ir,x=1,5),[RhL2(PPh3)2](ClO4)⋅2H2O (6),[PdL2]⋅2H2O (7),[PdL(phen)]Cl⋅H2O (8),[Re⁡OL2(PPh3)]Cl (9)and[UO2L2] (10)are reported, where LH is 4,6-diamino-1-hydro-5-hydroxy-pyrimidine-2-thione. The complexes were characterized by elemental analyses, physical techniques (molar conductivity, room-temperature magnetic susceptibility), and spectroscopic (IR, Raman, UV/VIS/ligand field, NMR, mass) methods. The ligandL−is in its thione form and behaves as a bidentate chelate with the deprotonated (hydroxyl) oxygen and the nitrogen of one amino group as donor atoms. Oxobridged dinuclear(1, 2)and various mononuclear(3–10)structures are assigned for the complexes in the solid state. The metal ion coordination geometries are octahedral(1–6, 9, 10)or square planar(7, 8). The free ligand LH and complexes1,4,7, and8were assayed in vitro for antimicrobial activity against two bacterial and two fungal cultures.

Structure of the complexes of ethylenediphosphinetetraacetic acid in solution

1985 ◽  
Vol 50 (2) ◽  
pp. 445-453 ◽  
Author(s):  
Jana Podlahová ◽  
Josef Šilha ◽  
Jaroslav Podlaha
Keyword(s):  
Metal Ion ◽  
Carboxyl Groups ◽  
Complex Solution ◽  
Square Planar ◽  
Weak Complexes ◽  
Carboxylic Groups ◽  
Uv Visible ◽  
The Stability ◽  
Tetrahedral Complexes ◽  
Free Carboxyl

Ethylenediphosphinetetraacetic acid is bonded to metal ions in aqueous solutions in four ways, depending on the type of metal ion: 1) through an ionic bond of the carboxylic groups to form weak complexes with a metal:ligand ratio of 1 : 1 (Ca(II), Mn(II), Zn(II), Pb(II), La(III)); 2) through type 1) bond with contributions from weak interaction with the phosphorus (Cd(II)); 3) through coordination of the ligand as a monodentate P-donor with the free carboxyl groups with formation of 2 : 1 and 1 : 1 complexes (Cu(I), Ag(I)); 4) through formation of square planar or, for Hg(II), tetrahedral complexes with a ratio of 1 : 2 with the ligand as a bidentate PP-donor with the free carboxyl groups (Fe(II), Co(II), Ni(II), Pd(II), Pt(II)). On acidification of the complex solution, the first two protons are bonded to the carboxyl groups. The behaviour during further protonation depends on the type of complex: in complexes of types 1) and 2) phosphorus is protonated and the complex dissociates; in complexes of types 3) and 4) the free carboxyl groups are protonated and the phosphorus-metal bond remains intact. The results are based on correlation of the stability constants, UV-visible, infrared, 1H and 31P NMR spectra and magnetic susceptibilities of the complexes in aqueous solution.

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