257. Geometrical isomerism of azo-compounds

Campbell, Neil; Henderson, Andrew W.; Taylor, Duncan M.

doi:10.1039/jr9530001281

Cited by 114 publications

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“…Materials 2-(Chlorophenylazo)pyridine [11] was prepared by a reported method. Pentacarbonyl-chlororhenium(I), triphenylphosphine and imidazole were obtained from Aldrich (USA).…”

Section: Methodsmentioning

confidence: 99%

“…Electronic spectral data of the complexes Compound UV-vis data a k max, nm (e b (dm 3 mol )1 cm )1 the effect of oxidation states on metalligand bond distances. The average Re-N(pyridine), Re-N(azo) and Re-Cl lengths are 2.067(10), 1.985(11) and 2.381(4) Å , respectively in Re II Cl 2 (L) 2 and 2.032(11), 1.987(11) and 2.352(4) Å , respectively in Re III (OPPh 3 )Cl 3 (L). Upon comparing the lengths 2.158 (3), 2.153(3) and 2.477 (1) Å respectively in Re I (CO) 3 Cl(L), the progressive contraction of the metal radius upon oxidation is neatly revealed.…”

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confidence: 99%

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Synthesis and structure of the 2-(chlorophenylazo)pyridine chelated tricarbonylrhenium(I) complex and its anion radical derivatives via electrochemical reduction

Sengupta

Panda

2005

Transition Met Chem

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Reacting Re(CO) 5 Cl with the azopyridine ligand (1) (L) in boiling benzene afford the complex Re(CO) 3 Cl(L), (2) in excellent yield [L=2-(p-Cl-C 6 H 4 NN)C 5 H 4 N]. The chelation of the azopyridine ligand accompanied by displacement of the two carbon monoxide ligands furnish a five-membered chelate ring. Structure determination of complex (2) has revealed a distorted octahedral ReC 3 N 2 Cl coordination sphere. The Re-N(pyridine) and, Re-N(azo) distances are 2.158(3) and 2.153(6) Å respectively, and the N-N length [1.273(4) Å ], implicate relatively weak Re-azo(p*) back-bonding. The Re(CO) 3 Cl(L) lattice consists of C-HÁ Á ÁCl hydrogen bonding and ClÁ Á ÁO non-bonded interactions constituting a supramolecular network. Extended Hu¨ckel calculations reveal that the LUMO of Re(CO) 3 Cl(L) is Ca. 57% azo in character. One-electron quasireversible electrochemical reduction of the complex occurs near )0.3

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“…Materials 2-(Chlorophenylazo)pyridine [11] was prepared by a reported method. Pentacarbonyl-chlororhenium(I), triphenylphosphine and imidazole were obtained from Aldrich (USA).…”

Section: Methodsmentioning

confidence: 99%

mentioning

confidence: 99%

Synthesis and structure of the 2-(chlorophenylazo)pyridine chelated tricarbonylrhenium(I) complex and its anion radical derivatives via electrochemical reduction

Sengupta

Panda

2005

Transition Met Chem

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“…2. When azpy ligand reacts with the metal, N (1) and N(3) are bonded to metal ion. This means that N(1) is more basic than N(2) and should be protonated.…”

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confidence: 99%

“…1 The azpy molecule contains one nitrogen on pyridine and one on the azo moiety. They are acting as the donor atoms to metal ions.…”

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confidence: 99%

Crystal Structure of the [Protonated 2-(phenylazo)pyridine and Protonated 2-(4-hydroxyphenylazo)pyridine (3:1)]tetrafluoroborate

et al. 2000

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In general, geometrical isomerism of azo-compounds is known to exist in two forms, cis and trans.However, 2-(phenylazo)pyridine (or azpy) was synthesized to be in trans form only by Campbell and coworkers. 1 The azpy molecule contains one nitrogen on pyridine and one on the azo moiety. They are acting as the donor atoms to metal ions. 2 In acidic solution, both nitrogens can react with protons. However, this gives rise to a question, which nitrogen is more basic towards protons. In this work, we confirm that the azo nitrogen is more basic than the other by X-ray analysis (Fig. 1).The 2-(phenylazo)pyridine (or azpy) was synthesized using literature procedures. 1 Concentrated HCl 2.5 mL was added to the aqueous solution containing CoCl2·H2O 0.5 mmol. Azpy 1.5 mmol in ethanolic solution was added to the cobalt solution. The mixture was stirred at room temperature for 10 min. Then H2O2 30% 3.5 mL and NH4PF4 2.5 mmol were added to the solution mixture. Single crystals of the protonated azpy were grown at 298 K by slow diffusion of hexane into the reaction mixture.The molecular structure of the title compound is shown in Fig. 2. When azpy ligand reacts with the metal, N(1) and N(3) are bonded to metal ion. This means that N(1) is more basic than N(2) and should be protonated. The difference-Fourier map showed a big electron density near N(1). The results from X-ray data indicate that the protonation occurs at the azo nitrogen (N1) and it is more strongly basic than the pyridine nitrogen (N3). In addition, N(1)-N(2) distance, which is similar to that of the azobenzene, is 1.248(4)Å.

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“…The molecule 2-(phenylazo)pyridine (azpy) is an azopyridine ligand system which has the N@CN@N chromophore [14,15]. This asymmetric bidentate ligand coordinates via the pyridine and aza nitrogen atoms, forming a stable 5-membered chelating ring [16,17] which is known to be capable of acting as both r donor and p acceptor.…”

Section: Introductionmentioning

confidence: 99%

The synthesis, chemical and biological properties of dichlorido(azpy)gold(III) chloride (azpy= 2-(phenylazo)pyridine) and the gold-induced conversion of the azpy ligand to the chloride of the novel tricyclic pyrido[2,1-c][1,2,4]benzotriazin-11-ium cation

Garza-Ortiz

Dulk

Brouwer

et al. 2007

Journal of Inorganic Biochemistry

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The synthesis, chemical and biological properties of dichlorido(azpy)gold(III) chloride (azpy = 2-(phenylazo)pyridine) and the gold-induced conversion of the azpy ligand to the chloride of the novel tricyclic pyrido [2,1-c] AbstractA new Au(III) coordination compound with the ligand 2-(phenylazo)pyridine has been synthesized and fully characterized by means of elemental analysis, IR, UV-visible, conductivity measurements, NMR, electrospray ionization (ESI-MS) and inductively coupled plasma optical emission spectrometry (ICP-OES). The chemical stability of the cation in this compound, [Au(azpy)Cl 2 ] + (abbreviated: Au-azpy), was analyzed by means of several physicochemical methods. While stable in the solid state, stability studies performed with the gold compound in solution showed an unexpected and unprecedented reactivity. A cationic organic derivative of 2-(phenylazo)pyridine, (abbreviated: pyrium), was produced from the solution and has been isolated as its chloride salt and characterized by crystal structure determination, elemental analysis, NMR, ESI-MS and conductivity studies in solution. This cyclization reaction is reported for the first time in the case of gold coordination compounds.The Au adduct and the pyrium cation were investigated as potential cytotoxic and anticancer agents, and both show moderate to high cytotoxic properties in cisplatin-sensitive and cisplatin-resistant ovarian carcinoma cell lines, A2780; and cisplatin-sensitive and cisplatinresistant murine lymphocytic leukemia cell lines, L1210. Significant anticancer activity against the cisplatin resistant cell lines was found for the pyrium salt, ruling out the occurrence of cross resistance phenomena.

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257. Geometrical isomerism of azo-compounds

Cited by 114 publications

References 0 publications

Synthesis and structure of the 2-(chlorophenylazo)pyridine chelated tricarbonylrhenium(I) complex and its anion radical derivatives via electrochemical reduction

Synthesis and structure of the 2-(chlorophenylazo)pyridine chelated tricarbonylrhenium(I) complex and its anion radical derivatives via electrochemical reduction

Crystal Structure of the [Protonated 2-(phenylazo)pyridine and Protonated 2-(4-hydroxyphenylazo)pyridine (3:1)]tetrafluoroborate

The synthesis, chemical and biological properties of dichlorido(azpy)gold(III) chloride (azpy= 2-(phenylazo)pyridine) and the gold-induced conversion of the azpy ligand to the chloride of the novel tricyclic pyrido[2,1-c][1,2,4]benzotriazin-11-ium cation

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