Structures of two isomers of dichlorobis(2-phenylazopyridine)ruthenium(II), [RuCl2(C11H9N3)2]

Seal, Alpana; Ray, Swati

doi:10.1107/s0108270184006302

Cited by 74 publications

(83 citation statements)

References 2 publications

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“…Noticeably shorter Ni-N distances [1.985 (9) and 1.974 (9)/1,] occur for azo N. Pyridine N is normally a better donor than azo N. Evidently the n-backbonding power of the azo function is very considerable, resulting in the net ((7 + n) bond order being larger in Ni-N(azo) than in Ni-N(py). A similar result has been obtained in two isomers of dichlorobis(2-phenylazopyridine)ruthenium(II) (Seal & Ray, 1984).…”

supporting

confidence: 70%

Structure of bis{2'-[α-(2-pyridyl)benzylidene]salicyclohydrazido}nickel(II) monohydrate, [Ni(C19H14N3O2)2].H2O

Seth¹,

Chakraborty²

1984

Acta Crystallogr C

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supporting

confidence: 70%

Structure of bis{2'-[α-(2-pyridyl)benzylidene]salicyclohydrazido}nickel(II) monohydrate, [Ni(C19H14N3O2)2].H2O

Seth¹,

Chakraborty²

1984

Acta Crystallogr C

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“…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.…”

mentioning

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 initial isomer assignment of the two cis-dichloro complexes -Cl and -Cl was confirmed by a crystallographic study in 1984, 9 and also by comparison of spectroscopic data of related [Ru(azpy) 2 X 2 ] (X = NNN or NO 2 ) complexes whose structures were determined by single-crystal X-ray diffraction studies. 10 A single-crystal X-ray diffraction study of the third isomer, as previewed by Chakravorty et al, 11 to the best of our knowledge has never been published by this group.…”

Section: Introductionmentioning

confidence: 81%

“…The molecular structures of two [Ru(azpy) 2 Cl 2 ] isomers, -Cl and -Cl, were published in 1984, 9 and the structure of the third isomer, -Cl, was reported in 2000. 12 In Fig.…”

Section: Xrd Data Of -Cl -Cl -Cl and -Clmentioning

confidence: 99%

Dichlorobis(2-phenylazopyridine)ruthenium(ii) complexes: characterisation, spectroscopic and structural properties of four isomers

et al. 2004

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The didentate ligand 2-phenylazopyridine (azpy) can -in theory -give rise to five different isomeric complexes of the type [Ru(azpy) 2 Cl 2 ], of which three have been known since 1980. The molecular structures of the cisdichlorobis(2-phenylazopyridine) ruthenium() complexes α-[Ru(azpy) 2 Cl 2 ] and β-[Ru(azpy) 2 Cl 2 ] (in which the coordinating pyridine nitrogen atoms are in mutually trans and cis positions, respectively, whilst the azo nitrogen atoms are in mutually cis positions) were unambiguously determined in the early 1980s. The third isomer, γ-[Ru(azpy) 2 Cl 2 ], has for two decades, erroneously, been assumed to be the all-trans isomer. In a recent communication we have proven that for this γ isomer the chloride ions are indeed in a trans geometry, but the pyridine nitrogen and azo nitrogen atoms of the two azpy ligands are in mutually cis geometries. In this paper the isolation of a fourth isomer is presented, the hitherto unknown δ-[Ru(azpy) 2 Cl 2 ]. The isomeric structure of δ-[Ru(azpy) 2 Cl 2 ] has been determined by 1 H-NMR spectroscopy and single-crystal X-ray diffraction analysis, and is the all-trans isomer. The bis(azpy)-ruthenium() isomers are of interest because of the pronounced cytotoxicity they exhibit against tumour cell lines and could be very useful in the search for structure-activity relationships of antitumour-active ruthenium complexes, as among the isomers there is a significant difference in activity. It is of paramount importance to have a good understanding of the structural and spectroscopic properties of these complexes, which in this paper are compared and discussed, with a particular emphasis on 1D and 2D 1 H NMR spectroscopies.

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Structures of two isomers of dichlorobis(2-phenylazopyridine)ruthenium(II), [RuCl2(C11H9N3)2]

Cited by 74 publications

References 2 publications

Structure of bis{2'-[α-(2-pyridyl)benzylidene]salicyclohydrazido}nickel(II) monohydrate, [Ni(C19H14N3O2)2].H2O

Structure of bis{2'-[α-(2-pyridyl)benzylidene]salicyclohydrazido}nickel(II) monohydrate, [Ni(C19H14N3O2)2].H2O

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

Dichlorobis(2-phenylazopyridine)ruthenium(ii) complexes: characterisation, spectroscopic and structural properties of four isomers

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