The redox kinetics of platinum(II)/(IV) complexes

Hindmarsh, K. W.; House, Donald A.; Eldik, Rudi van

doi:10.1016/s0020-1693(97)06171-9

Cited by 32 publications

(27 citation statements)

References 30 publications

Supporting

Mentioning

Contrasting

Order By: Relevance

“…The results are presented in Table 3, indicating that the reaction appeared to proceed with a negative entropy of activation. Negative entropy of activation has also been reported for a number of studies [27,28], especially when reaction proceeds via ion pairs of a similar kind. The activation enthalpies and entropies for the oxidation reactions were linearly related (r ¼ 0.992).…”

Section: Influence Of Temperaturementioning

confidence: 60%

“…Kinetic investigations of oxidations of organic [20][21][22][23] and inorganic substrates [24][25][26][27][28] by platinum(IV) have been reported. Recently, Arendse et al [29] studied the reduction of the platinum(IV) complexes [PtCl 2 (OH) 2 (N, N-dmen)]by sodium ascorbate with the isolation of the oxalatoplatinum(IV) complex, Pt(C 2 O 4 )Cl(OH)(N,Ndmen)] Á H 2 O, identified by an X-ray diffraction study.…”

Section: Introductionmentioning

confidence: 99%

See 1 more Smart Citation

Oxidative cleavage of α, β-unsaturated compounds by pentachlorohydroxoplatinate(IV) in alkaline medium

Pal¹,

Gupta

Sen

2005

Transition Met Chem

View full text Add to dashboard Cite

The kinetics of oxidation of a,b-unsaturated compounds by platinum(IV) in the presence of alkali {[OH ) ] ¼ (1-9) · 10 )3 mol dm )3 } have been investigated over the 303-318 K temperature range . The rate of the reaction is dependent on the first power of the concentrations of substrates, oxidant, and alkali. The rate constant increases with an increase in ionic strength and also with increasing dielectric constant of the medium. The oxidation rates follow the order: ACN > ACONH 2 > ACOO ) . The values of the third order rate constant (k 3 ) for the oxidation of acrylonitrile, acrylamide and acrylate are 1.24, 0.826 and 0.628 mol )2 dm 6 s )1 respectively, at 303 K. The oxidations of the substrates by PtCl 5 (OH) 2) take place by an inner-sphere mechanism. Platinum(IV) is reduced to platinum(II) by the substrates in a one-step two-electron transfer process to give reaction products. The major reaction product, HCHO, is identified from the reaction mixture using i.r. spectrometry, n.m.r. and C, H, N analysis. A tentative reaction mechanism, leading to the formation of products, has been suggested. The activation parameters of the reaction have been evaluated.

show abstract

Section: Influence Of Temperaturementioning

confidence: 60%

Section: Introductionmentioning

confidence: 99%

Oxidative cleavage of α, β-unsaturated compounds by pentachlorohydroxoplatinate(IV) in alkaline medium

Pal¹,

Gupta

Sen

2005

Transition Met Chem

View full text Add to dashboard Cite

show abstract

“…Most studies on ascorbic acid reduction of platinum(IV) complexes with either axial chlorido or hydroxido ligands suggested reduction mechanisms that were either outer-sphere or platinum(II) catalyzed inner-sphere mechanisms [68][69][70][71].…”

Section: Reduction By Ascorbatementioning

confidence: 99%

What do we know about the reduction of Pt(IV) pro-drugs?

Wexselblatt

Gibson

2012

Journal of Inorganic Biochemistry

321

320

View full text Add to dashboard Cite

“…[36][37][38][39][40] Kinetically, the reduction of Pt(IV) anticancer-model compounds and -prodrugs by Asc (Asc represents ether ascorbic acid or ascorbate or the sum of them) has been studied extensively. [13][14][15][16][17][18][19][20][21][22][23][24][25][26][27][28] However, most of these studies were carried out at a single pH or in a very narrow pH region. [13][14][15][16][17][20][21][22][23][24][25][26][27][28] Only two studies covered a certain pH range, 18,19 enabling the establishment of the rate expression in which the protolytic equilibria of Asc are involved.…”

Section: Introductionmentioning

confidence: 99%

“…Moreover, some discrepancies clearly exist in these studies as shown by the fact that the rate laws, the proposed reaction mechanisms, and the modes of electron transfer are different. [13][14][15][18][19][20][21]24 Comparatively, the reduction of Pt(IV) compounds by GSH and other small thiols has been exploited less extensively. 24,[29][30][31][32][33][34][35] In this work, we report a kinetic investigation of the reduction of [Pt(dach)Cl 4 ], cis-[Pt(NH 3 ) 2 Cl 4 ], and cis,cis,trans-[Pt(NH 3 ) 2 Cl 2 Br 2 ] by Asc, and the "observed activation parameters" (vide infra) at physiological pH (7.40); cis-[Pt(NH 3 ) 2 Cl 4 ], and cis,cis,trans-[Pt(NH 3 ) 2 Cl 2 Br 2 ] are the cisplatin prodrugs.…”

Section: Introductionmentioning

confidence: 99%

Reduction of ormaplatin and cis-diamminetetrachloroplatinum(iv) by ascorbic acid and dominant thiols in human plasma: kinetic and mechanistic analyses

et al. 2016

View full text Add to dashboard Cite

The reductions of Pt(iv) anticancer prodrugs [Pt(dach)Cl4] (ormaplatin/tetraplatin), cis-[Pt(NH3)2Cl4], and cis,cis,trans-[Pt(NH3)2Cl2Br2] by the several dominant reductants in human plasma have been characterized kinetically in this work, including l-ascorbic acid (Asc), l-glutathione (GSH), l-cysteine (Cys), dl-homocysteine (Hcy), and a dipeptide Gly-Cys. All the reductions follow an overall second-order kinetics, being first-order each in [Pt(iv)] and in the [reductant]. A general reactivity trend of Asc < Hcy < Cys-Gly < GSH < Cys is clearly revealed for the reductions of [Pt(dach)Cl4] and [Pt(NH3)2Cl4] at 37.0 °C and pH 7.40. Analysis of the observed second-order rate constants k' implies that these Pt(iv) prodrugs have a very short lifetime (less than a minute) in human plasma and can hardly enter into cells before reduction and that Asc might not play a dominant role in the reduction process among the reductants. The reductions of [Pt(dach)Cl4] and [Pt(NH3)2Cl4] by Asc have been studied in a wide pH range, and a reaction mechanism has been proposed involving parallel reductions of the Pt(iv) complexes by the Asc protolytic species. Moreover, a halide-bridged (inner-sphere) electron transfer mode for the rate-determining steps is discussed in detail; several lines of evidence strongly bolster this type of electron transfer. Furthermore, the observed activation parameters corresponding to k' have been measured around pH 7.40. Analysis of the established k'-pH profiles indicates that k' is a composite of at least three parameters in the pH range of 5.74-7.40 and the measured activation parameters in this range do not correspond to a single rate-determining step. Consequently, the isokinetic relationship reported previously using the measured ΔH(‡) and ΔS(‡) in the above pH range might be an artifact since the relationship is not justified anymore when our new data are added.

show abstract

The redox kinetics of platinum(II)/(IV) complexes

Cited by 32 publications

References 30 publications

Oxidative cleavage of α, β-unsaturated compounds by pentachlorohydroxoplatinate(IV) in alkaline medium

Oxidative cleavage of α, β-unsaturated compounds by pentachlorohydroxoplatinate(IV) in alkaline medium

What do we know about the reduction of Pt(IV) pro-drugs?

Reduction of ormaplatin and cis-diamminetetrachloroplatinum(iv) by ascorbic acid and dominant thiols in human plasma: kinetic and mechanistic analyses

Contact Info

Product

Resources

About