Metal complexes of 1,10-phenanthroline derivatives. XII. Complexes of 2-Hydrazino-1,10-phenanthroline and related molecules

1981 ◽  
Vol 34 (2) ◽  
pp. 313 ◽  
Author(s):  
AS Abushamleh ◽  
HA Goodwin
Keyword(s):  
Field Strength ◽  
Metal Complexes ◽  
Spectral Data ◽  
Chelating Agents ◽  
Spin Transition ◽  
Crossover Region ◽  
Lower Field ◽  
Derivatives Of

2-Hydrazino- and 2-(N1-methylhydrazino)-1,10-phenanthroline have been prepared from 2-chloro-1,10-phenanthroline and the appropriate hydrazine. These tridentate chelating agents yield bis-(ligand) complexes with nickel(II) and iron(II). Spectral data for the nicke(II) complexes indicate that the field strength of the ligands is near the crossover region for iron(II). Magnetic and M�ssbauereffect data indicate that a 5T2 ↔ 1A1 spin transition occurs in salts of the complex of the methylhydrazine derivative, though a marked anion-dependence for this transition is observed. Benzaldehyde hydrazone derivatives of both hydrazines also yielded six-coordinate nickel (II) and iron (II) complexes, but these were of significantly lower field strength than the parent hydrazines.

Metal complexes of 1,10-phenanthroline derivatives. X. 5T2 ↔ 1A1 transitions in iron(II) complexes of 2-(1,10-Phenanthrolin-2-yl)imidazole derivatives

1975 ◽  
Vol 28 (3) ◽  
pp. 505 ◽  
Author(s):  
DW Mather ◽  
HA Goodwin
Keyword(s):  
Metal Complexes ◽  
Temperature Dependence ◽  
Room Temperature ◽  
Chelating Agents ◽  
Elevated Temperatures ◽  
Magnetic Moments ◽  
Spin Transition ◽  
Benzimidazole Derivative ◽  
Crossover Region ◽  
Experimental Temperature Range

The preparation of the tridentate chelating agents 2-(1,10- phenanthrolin-2-yl)imidazoline and 2-(1,10-phenanthrolin-2- yl)benzimidazole and their bis-ligand complexes with iron(II) and nickel(II) is described. The latter ligand coordinates as either a neutral or anionic tridentate. Data from the spectra of the nickel(II) complexes indicate that the ligands have field strengths in the iron(II) crossover region. The temperature dependence of the magnetism of the imidazoline iron(II) complex reveals a gradual, temperature- induced 5T2 ↔ 1A1 transition which is not complete within the experimental temperature range (83-363 K). Both the cationic and neutral iron(II) complexes of the benzimidazole derivative are essentially low-spin at room temperature but a significant increase in their magnetic moments at elevated temperatures indicates that a spin transition may be occurring in these compounds too.

The singlet-quintet transition in Tris[2-(pyridin-2-yl)benzothiazole]iron(II) Bis(tetraphenylborate)

1984 ◽  
Vol 37 (6) ◽  
pp. 1157 ◽  
Author(s):  
AT Baker ◽  
HA Goodwin
Keyword(s):  
Field Strength ◽  
Spectral Data ◽  
Magnetic Moment ◽  
Spin Transition ◽  
Empirical Treatment ◽  
Temperature Dependent ◽  
Thermally Induced ◽  
Thiazole Derivative

The tris[2-(pyridin-2-yl)benzothiazole]iron(II) ion has been isolated as the tetraphenylborate salt which is stable in the atmosphere for short periods. The deep red complex displays a temperature-dependent magnetic moment and thermochroism which are associated with a thermally induced singlet (1A1) ↔ quintet (5T2) spin transition. An empirical treatment of the transition, which is continuous, yields ∆H and ∆S values of 22.7 kJ mol-1 and 91 JK-1 mol-1 over the range 275-364 K. Spectral data for the corresponding nickel(11) complex confirm the intermediate nature of the field strength of the benzothiazole and indicate that it is a weaker ligand than the corresponding thiazole derivative.

Sulphur-nitrogen chelating agents. VIII. Magnetic behaviour of some cobalt(II) complexes at the crossover region

1969 ◽  
Vol 22 (9) ◽  
pp. 1825 ◽  
Author(s):  
PSK Chia ◽  
SE Livingstone
Keyword(s):  
Field Strength ◽  
Thermal Equilibrium ◽  
Chelating Agents ◽  
Magnetic Behaviour ◽  
Ligand Field ◽  
Crossover Region ◽  
Methyl Group ◽  
Quantitative Treatment

The bis-ligand cobalt(II) complexes of 6-methylpyrid-2-yi-N-(2?- methylthio-phenyl)methyleneimine (SNNMe) are spin-free and the corresponding complexes of 2-pyridyl-N-(2?- methylthiophenyl)methyleneimine (SNN) are spin-paired. This difference in magnetic behaviour arises from a lower effective ligand field strength of SNNMe, presumably due to the steric inter-ligand interference introduced by the methyl group in the 6-position of SNNMe. The moments of the cobalt(II) complexes are dependent on temperature and the departures from the Curie-Weiss law are quite anomalous. No quantitative treatment is given for the anomalous magnetic behaviour; however, the results are best explained as a thermal equilibrium between the nearly equi-energetic spin-paired and spin-free states of the cobalt(II) atom.

Steric Effects of the Spin State of Iron(II) in Complexes of Substituted Bipyridine Derivatives

1991 ◽  
Vol 44 (11) ◽  
pp. 1539 ◽  
Author(s):  
D Onggo ◽  
HA Goodwin
Keyword(s):  
Field Strength ◽  
Spectral Data ◽  
Thermal Equilibrium ◽  
Steric Effects ◽  
Spin States ◽  
Anomalous Temperature Dependence ◽  
Anomalous Temperature ◽  
Thermally Induced ◽  
Infrared Spectral ◽  
Derivatives Of

Iron(II) and nickel(II) complexes of dimethyl 2,2′-bipyridine-3,3′-dicarboxylate (dmbc), 1,1′-biisoquinoline (biq), 6,6′-dimethyl-2,2′-bipyridine (dmbpy) and 4,4′6,6′-tetramethyl-2,2′- bipyridine (tmbpy) have been prepared. [FeN6]2+ derivatives of dmbc and biq were isolated as solid salts. These show anomalous temperature dependence of their magnetism and Mossbauer spectra which has been interpreted in terms of a thermally induced singlet (1A1) ↔ quintet (5T2) transition. The transition is also observed for [Fe(biq)3][BF4]2 in solution and has been analysed in terms of a thermal equilibrium involving the two spin states. Electronic spectral data for the [NiN6]2+ derivatives indicate values for the field strength of these ligands which are consistent with the appearance of the transition in the iron(II) species. Both dmbpy and tmbpy yield only bis(ligand) complexes with either iron(II) or nickel(II). Infrared spectral data suggest that in these complexes the associated perchlorate or fluoroborate anions are coordinated, which leads to distorted six-coordinate structures. A similar iron(II) complex was isolated with 2,9-dimethyl-1,10-phenanthroline.

Metal complexes of 1,10-Phenanthroline derivatives. VII. Complexes of 1,10-Phenanthroline-2-carbaldehyde hydrazones

1974 ◽  
Vol 27 (5) ◽  
pp. 965 ◽  
Author(s):  
HA Goodwin ◽  
DW Mather
Keyword(s):  
Field Strength ◽  
Metal Complexes ◽  
High Spin ◽  
Spin State ◽  
Spin Transition ◽  
Pronounced Change ◽  
Temperature Range ◽  
Spin Pairing ◽  
Bivalent Iron ◽  
Experimental Temperature Range

A series of substituted hydrazones derived from 1,l0-phenanthroline-2-carbaldehyde and their bis-ligand complexes with bivalent iron and nickel are described. The hydrazones show a gradation in field strength and this is reflected in the spin-state of the iron complexes. The methylhydrazone complex is essentially low-spin over the temperature range 83-363 K but the presence of some spin-free species at high temperatures is evident. Within the same range the dimethylhydrazone complex is essentially high-spin but undergoes significant spin-pairing and the phenylhydrazone complex displays a complete 5T2 → 1A1 spin transition. This transition is very sharp, resulting in a pronounced change in the magnetism, and colour, of the complex within a few degrees. Complexes of the 2-pyridylhydrazone, the methylphenylhydrazone and the diphenylhydrazone are high-spin over the entire experimental temperature range.

Sulphur-nitrogen chelating agents. III. Metal complexes of 2-methylthiomethylpyridine

1967 ◽  
Vol 20 (2) ◽  
pp. 239 ◽  
Author(s):  
PSK Chia ◽  
SE Livingstone ◽  
TN Lockyer
Keyword(s):  
Absorption Spectrum ◽  
Solid State ◽  
Metal Complexes ◽  
Spectral Data ◽  
High Spin ◽  
Chelating Agents ◽  
Chloride Ion ◽  
Visible Absorption Spectrum ◽  
Visible Absorption ◽  
Pyridine Nitrogen

Complexes of 2-methylthiomethylpyridine (mmp) have been obtained with cobalt(II), nickel(II), copper(II), copper(I), palladium(II), platinum(II), silver(I), and mercury(II). The compounds MX2 mmp2 (M = Co, Ni; X = Cl, Br, SCN) and NiI2 mmp2 are high-spin and their reflectance spectra indicate that the complexes are octahedral in the solid state. The visible absorption spectrum of CoCl2 mmp2 in nitrobenzene indicates that the complex is tetrahedral in solution with the ligand probably coordinated through the pyridine nitrogen only. The tris-chelated complexes [M mmp3](ClO4)2 were also characterized. Spectral data indicate that the complexes CuX2 mmp (X = Cl, Br) possess a tetragonal polymeric structure in the solid state. Conductimetric titration of the perchlorate [Cu mmp2](ClO4)2 with chloride ion in nitromethane demonstrated the formation of [CuCl mmp2]+ in solution. This was confirmed by the isolation of [CuCl mmp2]ClO4 and [CuBr mmp2]ClO4. The bis-chelated complex CuCl2 mmp2 gives a solution in nitrobenzene which is virtually non-conducting. The complexes PdX2 mmp (X = Cl, Br, I, SCN), Pt(SCN)2 mmp, [M mmp2]- (ClO4)2 (M = Pd, Pt, Hg), [Pt mmp2][PtCl4], and [Cu mmp2]ClO4 were also isolated. The silver(I) complex Ag mmp ClO4 probably contains the dimeric cation [Ag2 mmp2]2+.

scholarly journals Heteroarylazo derivatives of cyclohexane-1,3-dione and their metal complexes

2014 ◽  
Vol 79 (3) ◽  
pp. 303-311 ◽  
Author(s):  
Muhammed Ummathur ◽  
Damodaran Babu ◽  
Krishnannair Krishnankutty
Keyword(s):  
Metal Complexes ◽  
Spectral Data ◽  
1H Nmr ◽  
13C Nmr ◽  
Tautomeric Form ◽  
Tridentate Ligand ◽  
Mass Spectral Data ◽  
Mass Spectral ◽  
New Type ◽  
Derivatives Of

The coupling of diazotized 2-aminothiazole and 2-aminobenzo-thiazole with cyclohexane-1,3-dione yielded a new type of tridentate ligand systems (HL). Analytical, IR, 1H NMR, 13C NMR and mass spectral data indicate the existence of the compounds in the intramolecularly hydrogen bonded azo-enol tautomeric form. Monobasic tridentate coordination of the compounds in their [CuL(OAc)] and [ML2] complexes [M = Ni(II) and Zn(II)] has been established on the basis of analytical and spectral data. The Zn(II) chelates are diamagnetic while Cu(II) and Ni(II) complexes showed normal paramagnetic moment.

Metal complexes of 1,10-phenanthroline derivatives. IX. 5T2 ↔ 1A1 spin transitions in iron(II) complexes of 2-(1,10-phenanthrolin-2-yl)thiazole derivatives

1975 ◽  
Vol 28 (1) ◽  
pp. 33 ◽  
Author(s):  
HA Goodwin ◽  
DW Mather ◽  
FE Smith
Keyword(s):  
Metal Atom ◽  
Chelating Agents ◽  
Spin Transition ◽  
Nickel Complexes ◽  
Close Approach ◽  
Crossover Region ◽  
Thiazole Derivatives ◽  
Pyridyl Group ◽  
Spin Pairing ◽  
Experimental Temperature Range

The preparation of the tridentate chelating agents 2-(1,10- phenanthrolin-2-yl)thiazole, 2-(1,10-phenanthrolin-2-yl)-4-(2- pyridyl)thiazole 2-(1,10-phenanthrolin-2-yl)thiazolidine and 2-(1,10- phenanthrolin-2-yl)benzothiazole is described. Data from the spectra of the bis-ligand nickel complexes indicate that the ligands all have field strengths in the iron(II) crossover region. The temperature dependence of the magnetism of the bis-ligand iron(II) complexes reveals that, except for the complexes of the pyridylthiazole, a smooth, temperature-induced 5T2 ↔ 1A1 transition occurs in these compounds. For no complex is the transition complete within the experimental temperature range (83-363 K). The complex of the pyridylthiazole is high-spin throughout the range, the uncoordinated pyridyl group hindering the close approach of ligand and metal atom necessary for spin-pairing. The ability of the other ligands to induce a spin transition is primarily a consequence of distortions in the environment about the metal atom arising from coordination of the five- membered thiazole or related ring.

scholarly journals Functionalised Terpyridines and Their Metal Complexes—Solid-State Interactions

Chemistry ◽  
2021 ◽  
Vol 3 (1) ◽  
pp. 199-227
Author(s):  
Young Hoon Lee ◽  
Jee Young Kim ◽  
Sotaro Kusumoto ◽  
Hitomi Ohmagari ◽  
Miki Hasegawa ◽  
...  
Keyword(s):  
Solid State ◽  
Metal Complexes ◽  
Crystal Structures ◽  
Weak Interactions ◽  
Dispersion Interactions ◽  
Derivatives Of

Analysis of the weak interactions within the crystal structures of 33 complexes of various 4′-aromatic derivatives of 2,2′:6′,2″-terpyridine (tpy) shows that interactions that exceed dispersion are dominated, as expected, by cation⋯anion contacts but are associated with both ligand–ligand and ligand–solvent contacts, sometimes multicentred, in generally complicated arrays, probably largely determined by dispersion interactions between stacked aromatic units. With V(V) as the coordinating cation, there is evidence that the polarisation of the ligand results in an interaction exceeding dispersion at a carbon bound to nitrogen with oxygen or fluorine, an interaction unseen in the structures of M(II) (M = Fe, Co, Ni, Cu, Zn, Ru and Cd) complexes, except when 1,2,3-trimethoxyphenyl substituents are present in the 4′-tpy.

scholarly journals The Exchange of Cyclometalated Ligands

Molecules ◽  
2021 ◽  
Vol 26 (1) ◽  
pp. 210
Author(s):  
Alexander D. Ryabov
Keyword(s):  
Transition Metal ◽  
Metal Complexes ◽  
Transition Metal Complexes ◽  
Bond Activation ◽  
Bond Cleavage ◽  
Cyclopalladated Complexes ◽  
Derivatives Of ◽  
Cyclometalated Ligand ◽  
Incoming Ligand

Reactions of cyclometalated compounds are numerous. This account is focused on one of such reactions, the exchange of cyclometalated ligands, a reaction between a cyclometalated compound and an incoming ligand that replaces a previously cyclometalated ligand to form a new metalacycle: + H-C*~Z ⇄ + H-C~Y. Originally discovered for PdII complexes with Y/Z = N, P, S, the exchange appeared to be a mechanistically challenging, simple, and convenient routine for the synthesis of cyclopalladated complexes. Over four decades it was expanded to cyclometalated derivatives of platinum, ruthenium, manganese, rhodium, and iridium. The exchange, which is also questionably referred to as transcyclometalation, offers attractive synthetic possibilities and assists in disclosing key mechanistic pathways associated with the C–H bond activation by transition metal complexes and C–M bond cleavage. Both synthetic and mechanistic aspects of the exchange are reviewed and discussed.

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