1H NMR, EPR, UV−Vis, and Electrochemical Studies of Imidazole Complexes of Ru(III). Crystal Structures ofcis-[(Im)2(NH3)4RuIII]Br3and [(1MeIm)6RuII]Cl2·2H2O

Clarke, Michael J.; Bailey, V. M.; Doan, Peter E.; Hiller, Christian; Lachance-Galang, K. J.; Daghlian, H.; Mandal, Sisir K.; Bastos, Cecilia M.; Lang, D.

doi:10.1021/ic960355c

Cited by 59 publications

(57 citation statements)

References 43 publications

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“…3). The existence of a new absorption maximum in the visible region of the electronic spectra (Table 4) over 400 nm due to d-d transition was in accordance with the data from the IR-and 1 H-NMR spectra [26,27].…”

Section: Resultssupporting

confidence: 86%

Complexes of Ruthenium (III) with Some 2-Aminothiazole Derivatives

Nikolova

Ivanov²,

Bontchev

et al. 2011

Arzneimittelforschung

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Four new complexes of Ru(III) with a general formula [Ru(L)2Cl2]Cl, where L = 2-amino-4-phenylthiazole (CAS 2010-06-2), 2-amino-4-methylthiazole (CAS 1603-91-4), ethyl 2-amino-4-methyl-5-thiazolecarboxylate (CAS 7210-76-6) and ethyl 2-amino-4-phenyl-5-thiazolecarboxylate (CAS 64399-23-1), were prepared. The syntheses were carried out in polar medium and inert atmosphere at a molar ratio Ru:L = 1:2 or 1:3. The compounds obtained were characterised by IR-, 1H-NMR- 13C-NMR-, UV-VIS-, EPR spectroscopy, magnetochemical and conductivity measurements. The ligands behaved as bidental, bounding Ru(III) through the nitrogen atoms from the amino group and the heterocycle. The complex of ethyl 2-amino-4-phenyl-5-thiazolecarboxylate showed significant antileukaemic activity on various human cells (IC50 values ranging from 20 to 92 micromol/l). Toxicological studies on mice indicated that such concentrations could be reached without mortality. This compound exhibited a promising antineoplastic potential and needs further pharmacological and toxicological evaluation.

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Section: Resultssupporting

confidence: 86%

Complexes of Ruthenium (III) with Some 2-Aminothiazole Derivatives

Nikolova

Ivanov²,

Bontchev

et al. 2011

Arzneimittelforschung

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“…Clarke and co-workers have reported EPR spectra for cis -[Ru III (NH 3 ) 4 (Him) 2 ]Br 3 . 77 It is possible to use analytical equations given by McGarvey to extract an internally consistent set of LFT parameters from the experimental g values. 78 This has been done here and the results are given in Table 4.…”

Section: Resultsmentioning

confidence: 99%

“…The g values presented are all for complexes with tetraethylammonium countercation; for trans -Cs[OsCl 4 (CO)(py)]: g ⊥ = 2.46, g ║ = 1.45. c Taken from Ni Dhubhghaill et al 82 d Taken from de Paula et al 80 The g values reported are for the solid material; in aqueous or methanol solution, multiple species are reported due to replacement of Me 2 SO and/or chlorido ligands by solvent. e Taken from Clarke et al 77 The values for | g min | were not observed (hence they are given in parentheses), but were proposed by their LFT analysis. In these systems, the proper choice of sign of the g values is not apparent based on standard criteria, namely the magnitudes of k or Δ, so both choices are given.…”

Section: Figurementioning

confidence: 99%

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cis-Tetrachlorido-bis(indazole)osmium(iv) and its osmium(iii) analogues: paving the way towards the cis-isomer of the ruthenium anticancer drugs KP1019 and/or NKP1339

et al. 2017

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The relationship between cis-trans isomerism and anticancer activity has been mainly addressed for square-planar metal complexes, in particular, for platinum(II), e.g., cis- and trans-[PtCl2(NH3)2], and a number of related compounds, of which, however, only cis-counterparts are in clinical use today. For octahedral metal complexes, this effect of geometrical isomerism on anticancer activity has not been investigated systematically, mainly because the relevant isomers are still unavailable. An example of such an octahedral complex is trans-[RuCl4(Hind)2]−, which is in clinical trials now as its indazolium (KP1019) or sodium salt (NKP1339), but the corresponding cis-isomers remain inaccessible. We report the synthesis of Na[cis-OsIIICl4(κN2-1H-ind)2] (Na[1]) to show that cis-isomer of NKP1339 can in principle be prepared as well. The procedure involves heating (H2ind)[OsIVCl5(κN1-2H-ind)] in a high boiling point organic solvent resulting in an Anderson rearrangement with formation of cis-[OsIVCl4(κN2-1H-ind)2] ([1]) in high yield. The transformation is accompanied by an indazole coordination mode switch from κN1 to κN2 and stabilization of the 1H-indazole tautomer. Fully reversible spectroelectrochemical reduction of [1] in acetonitrile at 0.46 V vs NHE is accompanied by a change in electronic absorption bands indicating formation of cis-[OsIIICl4(κN2-1H-ind)2]− ([1]−). Chemical reduction of [1] in methanol with NaBH4 followed by addition of nBu4NCl afforded the osmium(III) complex nBu4N[cis-OsIIICl4(κN2-1H-ind)2] (nBu4N[1]). Metathesis reaction of nBu4N[1] with an ion exchange resin led to isolation of the water-soluble salt Na[1]. The X-ray diffraction crystal structure of [1]·Me2CO was determined and compared with that of trans-[OsIVCl4(κN2-1H-ind)]·2Me2SO (2·2Me2SO), also prepared in this work. EPR spectroscopy was performed on the OsIII complexes and the results analyzed by ligand-field and quantum chemical theories. We furthermore assayed effects of [1] and Na[1] on cell viability and proliferation in comparison to trans-[OsIVCl4(κN1-2H-ind)] [3] and cisplatin and found a strong reduction of cell viability at concentrations between 30 and 300 µM in different cancer cell lines (HT29, H446, 4T1 and HEK293). HT-29 cells are less sensitive to cisplatin than 4T1 cells, but more sensitive to [1] and Na[1], as shown by decreased proliferation and viability as well as an increased late apoptotic/necrotic cell population.

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“…Complexes of divalent metal ions such as copper, nickel, cobalt, zinc or iron with imidazole and its derivatives have attracted attention because of their relation to a variety of biologically important molecules which involve the bonding of the metal ion with the imidazole rings of the histidine unit (Sundberg & Martin, 1974). Ruthenium complexes with imidazole ligands are of interest for their biochemical activity (Clarke et al, 1996). A protein purification method, known as immobilized-metal-ion affinity chromatography (IMAC) and based on the binding of, e.g., histidine to immobilized metal ions, provides another source of interest.…”

Section: Commentmentioning

confidence: 99%