The mechanisms of halide interchange reactions of hexahalogenoplatinate(IV) complexes. The PtBr2−6-I− reaction.

Bounsall, E. J.; Hewkin, D. J.; Hopgood, D.; Poë, Anthony J.

doi:10.1016/s0020-1693(00)93187-6

Cited by 9 publications

(2 citation statements)

References 13 publications

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“…The rate constants at 17.1 "C interpolate quite well into the rather scattered data in ref. 5 but Fig. 1 shows that the rates are dependent on the p H of the solutions.…”

Section: Stage I1mentioning

confidence: 93%

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Redox Interchange Reactions of Halogenoplatinum(IV) Complexes. pH Dependence of the Hexabromoplatinate(IV)–Iodide Reactions

Johnson¹,

Poë²

1974

Can. J. Chem.

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Reaction mechanisms of platinum(1V) complexes have recently been reviewed (1, 2). One that is of particular importance for halide interchange reactions of anionic complexes is reductive elimination followed by oxidative addition (r.e.0.a.). Proposed originally by Grinberg and co-worker (3) it has recently been confirmed and elaborated (4). This mechanism is believed to operate in the reaction of [~t~r , ]~-with iodide to form [PtI,, a reaction that proceeds in three kinetically distinct stages, each of which was proposed to be of the form shown in reaction 1 where the four ligands in the plane perpen-very fast dicular to the page (omitted for simplicity) were Br,, trans-Br,I,, and I, in the first, second, and third stages, respectively. This conclusion was based in part on the observation that the second and third stages were also detected after the very rapid oxidation of [PtBr,12-by I,--I-mixtures. However, a study of the p H dependence of the reactions has shown that Stages I1 and I11 are more complicated than this, each consisting of at least two parallel reactions, but that no change is necessary in the basic type of mechanism proposed. Experimental and ResultsSodium hexabromoplatinate(1V) hexahydrate, sodium hexachloroiridate(IV), and potassium tetrabromoplatinate(I1) (Johnson, Mathey and Mallory, Ltd.) were used as received. The kinetics were followed in the same way as before (5), reacting solutions being contained in tightly stoppered cells in the thermostatted cell holder of a Perkin-Elmer 402 or Cary 16K recording spectrophotometer and the changing absorbance at a fixed wavelength being followed automatically. The temperatures of the solutions were measured directly with a calibrated thermistor and Wheatstone Bridge, and were constant to within 1 0 . 0 5 "C throughout the period of the reactions. The ionic strengths of the solutions were controlled by addition of sodium perchlorate and their p H values were adjusted with standard perchloric acid solutions, the values being measured with an Instrumental Laboratory, Model 205, p H meter. Stage IThe kinetics were followed in the presence of a pseudo-first-order excess of iodide by observing the growth in absorbance at 430 nm which is ' T o whom all correspondence should be addressed.close to an isosbestic point for Stage 11. IsosCan. J. Chem. Downloaded from www.nrcresearchpress.com by 54.245.13.81 on 05/12/18For personal use only.

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“…The rate constants at 17.1 "C interpolate quite well into the rather scattered data in ref. 5 but Fig. 1 shows that the rates are dependent on the p H of the solutions.…”

Section: Stage I1mentioning

confidence: 93%

“…k,, are the second-order rate constants for the slow reduction of the aquo and hydroxy complexes, respectively. Equation 4 can be rearranged to give [5]. Above p H ca.…”

Section: Data Inmentioning

confidence: 99%

Redox Interchange Reactions of Halogenoplatinum(IV) Complexes. pH Dependence of the Hexabromoplatinate(IV)–Iodide Reactions

Johnson¹,

Poë²

1974

Can. J. Chem.

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ETC: Ein mechanistisches Konzept für Anorganische und Organische Chemie

Chanon¹,

Tobe

1982

Angewandte Chemie

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Das Konzept der Elektronen‐Transfer‐Katalyse (ETC) oder, etwas spezifischer, der zweifachen Aktivierung durch Ein‐Elektronen‐Übertragung (DAISET) eröffnet die Möglichkeit, scheinbar nicht zusammenhängende experimentelle Befunde miteinander zu verknüpfen. Bei der ersten Aktivierung nimmt das Substrat ein Elektron auf oder gibt ein Elektron ab; bei der zweiten Aktivierung bildet sich eine Reaktionskette, die das im ersten Schritt erzeugte Teilchen ständig reproduziert. Der Beitrag beginnt mit einer Diskussion des SRN1‐Mechanismus. Beispiele für die Anwendung des Konzepts sind thermische und photochemische Austauschreaktionen an PtIV‐Komplexen, die Austauschreaktion [AuCl4]−/Cl−, Umsetzungen von Grignard‐ und anderen Organometall‐Reagentien sowie das Redoxverhalten elektronisch angeregter organischer Verbindungen. Photochemische Anwendungsmöglichkeiten schließen die potentielle Nutzung der Sonnenenergie ein. Neue Aspekte ergeben sich auch für das mechanistische Problem „SN2‐Reaktion oder SET‐Prozeß?”︁ Das Konzept hat außerdem Bedeutung für SH2‐Reaktionen am Metallzentrum, Molekül‐induzierte Homolysen, Reaktionen von Komplexen sowie elektrochemische Vorgänge. — Sofern nicht anders vermerkt, werden in diesem Beitrag nur Doppelaktivierungs‐(DAISET‐)Prozesse erörtert.

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ETC: A Mechanistic Concept for Inorganic and Organic Chemistry

Chanon¹,

Tobe

1982

Angew. Chem. Int. Ed. Engl.

164

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Dedicated 10 Professor Jacques Metzger on the occasion of his 60th birthdayThe concept of electron transfer catalysis (ETC), or more specifically "Double Activation Induced by Single Electron Transfer" (DAISET) gives an opportunity to connect experimental facts never previously correlated. The first activation results from the transfer of an electron to (or from) a molecular species; the second activation results from the build-up of a reaction chain able to reproduce the species formed in the first step. The starting point of this review is the SRN I mechanism where principle and experimental diagnostic criteria are critically discussed. The thermal and photochemical exchange and substitution reactions of Pt'" complexes are then reviewed together with the exchange reaction [AuCI,]-/CI -, reactions with Grignard reagents and other organometallic reagents, as well as the redox behavior of electronically excited organic compounds. Photochemical applications, including solar energy conversion are discussed. New aspects are also presented for the mechanistic problem "S,2 reaction or SET process?" Moreover, the concept has significance for St12 reactions at metal centers, molecule-induced homolyses, reactions of complexes, as well as electrochemical processes.-Unless otherwise specified, only double activation (DAISET) processes will be discussed in this article.

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The mechanisms of halide interchange reactions of hexahalogenoplatinate(IV) complexes. The PtBr2−6-I− reaction.

Cited by 9 publications

References 13 publications

Redox Interchange Reactions of Halogenoplatinum(IV) Complexes. pH Dependence of the Hexabromoplatinate(IV)–Iodide Reactions

Redox Interchange Reactions of Halogenoplatinum(IV) Complexes. pH Dependence of the Hexabromoplatinate(IV)–Iodide Reactions

ETC: Ein mechanistisches Konzept für Anorganische und Organische Chemie

ETC: A Mechanistic Concept for Inorganic and Organic Chemistry

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