“Lantern‐Shaped” Platinum(III) Complexes with Axially Bound 9‐Ethylguanine or 1‐Methylcytosine (L) of General Formula [Pt2{HN=C(But)O}4L2](NO3) 2

Pacifico, Concetta; Intini, Francesco P.; Nushi, Fiorentin; Natile, Giovanni

doi:10.1155/2010/102863

Cited by 7 publications

(2 citation statements)

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“…[1,2] Mononuclear complexes are particularly elusive, while it is more common to find binuclear Pt III complexes presenting a metal-metal s bond engaging the unpaired electrons on each metal center, thus abolishing radical character and improving stability. [2,[3][4][5] Pt III has been also described in the solid state as component of the polymeric material named "platinblau". [6] A formal Pt III dimeric cation has been generated by electrospray ionization of a tetrameric Pt II precursor.…”

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confidence: 99%

Can an Elusive Platinum(III) Oxidation State be Exposed in an Isolated Complex?

et al. 2020

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Platinum(IV) complexes are extensively studied for their activity against cancer cells as potential substitutes for the widely used platinum(II) drugs. PtIV complexes are kinetically inert and need to be reduced to PtII species to play their pharmacological action, thus acting as prodrugs. The mechanism of the reduction step inside the cell is however still largely unknown. Gas‐phase activation of deprotonated platinum(IV) prodrugs was found to generate products in which platinum has a formal +3 oxidation state. IR multiple photon dissociation spectroscopy is thus used to obtain structural information helping to define the nature of both the platinum atom and the ligands. In particular, comparison of calculations at DFT, MP2 and CCSD levels with experimental results demonstrates that the localization of the radical is about equally shared between the dxz orbital of platinum and the pz of nitrogen on the amino group, the latter acting as a non‐innocent ligand.

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confidence: 99%

Can an Elusive Platinum(III) Oxidation State be Exposed in an Isolated Complex?

et al. 2020

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“…As previously observed in similar cases, the short distance between the two platinum atoms in the starting platinum(II) substrate would favour the formation of the direct intermetallic Pt-Pt bond present in Pt III dimers. 39 Unexpectedly, by treating an aqueous solution of the Pt(II) derivative [{Pt-(en)} 2 (μ-AHBP-H 2 )](HSO 4 ) with a saturated solution of Cl 2(g) in CCl 4 (Scheme 4), we did not obtain a Pt(III) derivative but, instead, the dinuclear Pt(IV) complex 3.…”

Section: Synthesis and Characterization Of A Dinuclear Platinum(iv) C...mentioning

confidence: 94%

Dinuclear Pt(ii)-bisphosphonate complexes: a scaffold for multinuclear or different oxidation state platinum drugs

et al. 2012

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Geminal bisphosphonates (BPs), used in the clinic for the treatment of hypercalcaemia and skeletal metastases, have been also exploited for promoting the specific accumulation of platinum antitumor drugs in bone tissue. In this work, the platinum dinuclear complex [{Pt(en)}(2)(μ-AHBP-H(2))](+) (1) (the carbon atom bridging the two phosphorous atoms carrying a 2-ammonioethyl and a hydroxyl group, AHBP-H(2)) has been used as scaffold for the synthesis of a Pt(II) trinuclear complex, [{Pt(en)}(3)(μ-AHBP)](+) (2), and a Pt(IV) adamantane-shaped dinuclear complex featuring an oxo-bridge, [{Pt(IV)(en)Cl}(2)(μ-O)(μ-AHBP-H(2))](+) (3) (X-ray structure). Compound 2 undergoes a reversible, pH dependent, rearrangement with a neat switch point around pH = 5.4. Compound 3 undergoes a one-step electrochemical reduction at E(pc) = -0.84 V affording compound 1. Such a potential is far lower than that of glutathione (-0.24 V), nevertheless compound 3 can undergo chemical reduction to 1 by GSH, most probably through a different (inner-sphere) mechanism. In vitro cytotoxicity of the new compounds, tested against murine glioma (C6) and human cervix (HeLa) and hepatoma (HepG2) cell lines, has shown that, while the Pt(IV) dimer 3 is inactive up to a concentration of 50 μM, the two Pt(II) polynuclear compounds 1 and 2 have a cytotoxicity comparable to that of cisplatin with the trinuclear complex 2 generally more active than the dinuclear complex 1.

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Conditions Favoring the Formation of Monomeric Pt^III Derivatives in the Electrochemical Oxidation of trans‐[Pt^II{(p‐BrC₆F₄)NCH₂CH₂NEt₂}Cl(py)]

et al. 2015

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Characterization of the anticancer active compound trans‐[PtII{(p‐BrC6F4)NCH2CH2NEt2}Cl(py)] is described along with identification of electrochemical conditions that favor formation of a monomeric one‐electron‐oxidized PtIII derivative. The square‐planar organoamidoplatinum(II) compound was synthesized through a carbon dioxide elimination reaction. Structural characterization by using single‐crystal X‐Ray diffraction reveals a trans configuration with respect to donor atoms of like charges. As PtIII intermediates have been implicated in the reactions of platinum anticancer agents, electrochemical conditions favoring the formation of one‐electron‐oxidized species were sought. Transient cyclic voltammetry at fast scan rates or steady‐state rotating disc and microelectrode techniques in a range of molecular solvents and an ionic liquid confirm the existence of a well‐defined, chemically and electrochemically reversible one‐electron oxidation process that, under suitable conditions, generates a PtIII complex, which is proposed to be monomeric [PtIII{(p‐BrC6F4)NCH2CH2NEt2}Cl(py)]+. Electron paramagnetic resonance spectra obtained from highly non‐coordinating dichloromethane/([Bu4N][B(C6F5)4]) solutions, frozen to liquid nitrogen temperature immediately after bulk electrolysis in a glove box, support the PtIII assignment rather than formation of a PtII cation radical. However, the voltammetric behavior is highly dependent on the timescale of the experiments, temperature, concentration of trans‐[PtII{(p‐BrC6F4)NCH2CH2NEt2}‐ Cl(py)], and the solvent/electrolyte. In the low‐polarity solvent CH2Cl2 containing the very weakly coordinating electrolyte [Bu4N][B(C6F5)4], a well‐defined reversible one‐electron oxidation process is observed on relatively long timescales, which is consistent with the stabilization of the cationic platinum(III) complex in non‐coordinating media. Bulk electrolysis of low concentrations of [Pt{(p‐BrC6F4)NCH2CH2NEt2}Cl(py)] favors the formation of monomeric [PtIII{(p‐BrC6F4)NCH2CH2NEt2}Cl(py)]+. Simulations allow the reversible potential of the PtII/PtIII process and the diffusion coefficient of [PtIII{(p‐BrC6F4)‐ NCH2CH2NEt2}Cl(py)]+ to be calculated. Reversible electrochemical behavior, giving rise to monomeric platinum(III) derivatives, is rare in the field of platinum chemistry.

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“Lantern‐Shaped” Platinum(III) Complexes with Axially Bound 9‐Ethylguanine or 1‐Methylcytosine (L) of General Formula [Pt2{HN=C(But)O}4L2](NO3) 2

Cited by 7 publications

References 63 publications

Can an Elusive Platinum(III) Oxidation State be Exposed in an Isolated Complex?

Can an Elusive Platinum(III) Oxidation State be Exposed in an Isolated Complex?

Dinuclear Pt(ii)-bisphosphonate complexes: a scaffold for multinuclear or different oxidation state platinum drugs

Conditions Favoring the Formation of Monomeric Pt^III Derivatives in the Electrochemical Oxidation of trans‐[Pt^II{(p‐BrC₆F₄)NCH₂CH₂NEt₂}Cl(py)]

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“Lantern‐Shaped” Platinum(III) Complexes with Axially Bound 9‐Ethylguanine or 1‐Methylcytosine (L) of General Formula [Pt2{HN=C(But)O}4L2](NO3) 2

Cited by 7 publications

References 63 publications

Can an Elusive Platinum(III) Oxidation State be Exposed in an Isolated Complex?

Can an Elusive Platinum(III) Oxidation State be Exposed in an Isolated Complex?

Dinuclear Pt(ii)-bisphosphonate complexes: a scaffold for multinuclear or different oxidation state platinum drugs

Conditions Favoring the Formation of Monomeric PtIII Derivatives in the Electrochemical Oxidation of trans‐[PtII{(p‐BrC6F4)NCH2CH2NEt2}Cl(py)]

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Conditions Favoring the Formation of Monomeric Pt^III Derivatives in the Electrochemical Oxidation of trans‐[Pt^II{(p‐BrC₆F₄)NCH₂CH₂NEt₂}Cl(py)]