Advanced

Water exchange of trans-dichlorodiaquaplatinum(II) and tetraaquaplatinum(II) studied by an oxidative-addition quenching technique. Isotopic shifts and platinum-195 NMR chemical shifts for mixed chloro-aqua complexes of platinum(II) and platinum(IV)

Gröning, Östen and Elding, Lars Ivar LU (1989) In Inorganic Chemistry 28(17). p.3366-3372
Abstract
Water exchange on Pt(H20)42+ and trans-PtCI2(H20)2 has been studied by means of a new oxygen18 tracing technique. The exchange between a platinum(II) complex and 018-enriched water has been rapidly quenched by addition of excess chlorine, which gives a substitution-inert platinum(IV) complex. The time-dependent oxygen16/oxygen18 distributions of the platinum(II) complexes are obtained from the 195Pt NMR spectra of the corresponding oxidized complexes, which display well-resolved oxygen isotopic shifts in the 78-MHz signal. Product identification based on the isotopic splitting of the NMR signal due to both 160/180 and 35C1/37C1 shows that the oxidation takes place without scrambling and involves the formation of a CI-Pt-OH, axis... (More)
Water exchange on Pt(H20)42+ and trans-PtCI2(H20)2 has been studied by means of a new oxygen18 tracing technique. The exchange between a platinum(II) complex and 018-enriched water has been rapidly quenched by addition of excess chlorine, which gives a substitution-inert platinum(IV) complex. The time-dependent oxygen16/oxygen18 distributions of the platinum(II) complexes are obtained from the 195Pt NMR spectra of the corresponding oxidized complexes, which display well-resolved oxygen isotopic shifts in the 78-MHz signal. Product identification based on the isotopic splitting of the NMR signal due to both 160/180 and 35C1/37C1 shows that the oxidation takes place without scrambling and involves the formation of a CI-Pt-OH, axis perpendicular to the original coordination plane of platinum(II). The oxidation products of Pt(H20)42+, trans-PtCl2(H2O)2, and PtC142- are thus found to be PtCI(H20)53+, mer-PtCI3(H20)3+, and PtC15H20-, respectively. There is no observable exchange of trans- and cis-aqua ligands in those platinum(IV) complexes during the time required to accumulate the spectra. Water exchange of trans-PtCl2(H20)2 is slower than that of Pt(H20)42+ by a factor of 30. The statistically corrected rate constants are kex298 = (1.58+-0.03) x10-5 s-I and kex298 = (4.8+-0.1)x10-4 s-I, respectively. Variable-temperature measurements (278-303 K) gave DeltaH' = (92+-2) kJ mol-' and DeltaS' = (0+-5) J K-1 mol-1 for exchange on Pt(H20)42+. The effect of the non-reacting ligands is basically the same as that previously reported for the chloride anation reactions of these two substrates. The chemical shifts of the complexes PtCl(4-n)(H20)n2-n, n = 0-4, have been measured in a 1.00 M HCIO4 medium. The increment in the chemical shift for substitution of water by chloride is smaller trans to water than trans to chloride but increases with the number of chloride ligands in a cis position to the replaced water molecule. This might be consistent with a large ground-state trans influence of chloride compared to water and a negligible relative cis influence. (Less)
Please use this url to cite or link to this publication:
author
organization
publishing date
type
Contribution to journal
publication status
published
subject
keywords
Water exchange, Platinum(II), Platinum(IV), Oxidative addition, Platinum-195 NMR, Isotopic shifts, Mixed Chloro-Aqua complex, Water exchange, Platinum(II), Oxygen-18 tracing, 195-Platinum NMR, Oxygen isotopic shifts, Isotopic splitting of NMR signals, Chlorine isotopic shifts, Oxidation with chlorine, Pt(II) chloro aqua complexes , Pt(IV) chloro aqua complexes
in
Inorganic Chemistry
volume
28
issue
17
pages
7 pages
publisher
The American Chemical Society
external identifiers
  • scopus:0000505685
ISSN
1520-510X
DOI
10.1021/ic00316a026
language
English
LU publication?
yes
id
52083b32-0c01-4ded-834d-00c4a824ca53
date added to LUP
2017-01-09 12:43:04
date last changed
2017-05-29 11:37:35
@article{52083b32-0c01-4ded-834d-00c4a824ca53,
  abstract     = {Water exchange on Pt(H20)42+ and trans-PtCI2(H20)2 has been studied by means of a new oxygen18 tracing technique. The exchange between a platinum(II) complex and 018-enriched water has been rapidly quenched by addition of excess chlorine, which gives a substitution-inert platinum(IV) complex. The time-dependent oxygen16/oxygen18 distributions of the platinum(II) complexes are obtained from the 195Pt NMR spectra of the corresponding oxidized complexes, which display well-resolved oxygen isotopic shifts in the 78-MHz signal. Product identification based on the isotopic splitting of the NMR signal due to both 160/180 and 35C1/37C1 shows that the oxidation takes place without scrambling and involves the formation of a CI-Pt-OH, axis perpendicular to the original coordination plane of platinum(II). The oxidation products of Pt(H20)42+, trans-PtCl2(H2O)2, and PtC142- are thus found to be PtCI(H20)53+, mer-PtCI3(H20)3+, and PtC15H20-, respectively. There is no observable exchange of trans- and cis-aqua ligands in those platinum(IV) complexes during the time required to accumulate the spectra. Water exchange of trans-PtCl2(H20)2 is slower than that of Pt(H20)42+ by a factor of 30. The statistically corrected rate constants are kex298 = (1.58+-0.03) x10-5 s-I and kex298 = (4.8+-0.1)x10-4 s-I, respectively. Variable-temperature measurements (278-303 K) gave DeltaH' = (92+-2) kJ mol-' and DeltaS' = (0+-5) J K-1 mol-1 for exchange on Pt(H20)42+. The effect of the non-reacting ligands is basically the same as that previously reported for the chloride anation reactions of these two substrates. The chemical shifts of the complexes PtCl(4-n)(H20)n2-n, n = 0-4, have been measured in a 1.00 M HCIO4 medium. The increment in the chemical shift for substitution of water by chloride is smaller trans to water than trans to chloride but increases with the number of chloride ligands in a cis position to the replaced water molecule. This might be consistent with a large ground-state trans influence of chloride compared to water and a negligible relative cis influence. },
  author       = {Gröning, Östen  and Elding, Lars Ivar},
  issn         = {1520-510X},
  keyword      = {Water exchange,Platinum(II),Platinum(IV),Oxidative addition,Platinum-195 NMR,Isotopic shifts,Mixed Chloro-Aqua complex,Water exchange,Platinum(II),Oxygen-18 tracing,195-Platinum NMR,Oxygen isotopic shifts,Isotopic splitting of NMR signals,Chlorine isotopic shifts,Oxidation with chlorine,Pt(II) chloro aqua complexes ,Pt(IV) chloro aqua complexes},
  language     = {eng},
  number       = {17},
  pages        = {3366--3372},
  publisher    = {The American Chemical Society},
  series       = {Inorganic Chemistry},
  title        = {Water exchange of trans-dichlorodiaquaplatinum(II) and tetraaquaplatinum(II) studied by an oxidative-addition quenching technique. Isotopic shifts and platinum-195 NMR chemical shifts for mixed chloro-aqua complexes of platinum(II) and platinum(IV)},
  url          = {http://dx.doi.org/10.1021/ic00316a026},
  volume       = {28},
  year         = {1989},
}