Disodium Tetrachloroplatinate(II)1


[10026-00-3]  · Cl4Na2Pt  · Disodium Tetrachloroplatinate(II)  · (MW 382.86)

(homogeneous hydrogen isotope exchange catalyst;2 selective oxidative functionalization of alkane C-H bonds;3 isomerization of alkenes4)

Solubility: sol H2O (8 g/100 mL); slightly sol alcohol, acetone, acetic acid.

Form Supplied in: red-brown solid; available as a tetrahydrate Na2PtCl4.4H2O. Drying: at 120 °C/0.1 mmHg for 24 h.

Handling, Storage, and Precautions: should be stored in the absence of moisture; irritating to skin, eyes, and respiratory organs; corrosive.

Hydrogen Isotope Exchange Catalyst.

Aromatic and aliphatic compounds undergo exchange of isotopic hydrogen with a catalytic amount of this reagent (see also Dipotassium Tetrachloroplatinate(II)). This system is valuable for labeling compounds with deuterium and/or tritium in one step and constitutes the homogeneous equivalent of the well-known heterogeneous platinum technique. A wide range of compounds, including benzene and substituted benzenes,5 polyphenyls,6 polycyclic hydrocarbons,7 and some steroids8 undergo D and/or T exchange. Deuteration in the side chain of long-chain alkylbenzenes occurs predominately at the benzylic and the terminal carbons.9 Aromatics are generally quite reactive, whereas aliphatics such as cyclohexane exchange very slowly.10 Nitrobenzene has similar reactivity to toluene11 and bromobenzene.12 Exchange usually occurs only in the sterically unhindered meta and para positions (eq 1).11 Aromatic a-hydroxy acids undergo oxidative decarboxylation during the Na2PtCl4-catalyzed homogeneous deuteration (eq 2).13

Functionalization of Saturated Hydrocarbons.

Na2PtCl4 or the combination Na2PtCl4/Na2PtCl6 in aqueous solution can be used to functionalize saturated hydrocarbons (see also Dipotassium Tetrachloroplatinate(II)). Unusual and often very high selectivity is observed for oxidation at what are more commonly the least reactive positions. The products from oxidation of alkanes are mainly alcohols together with chloroalkanes, ethers, and acids. Ethanol can be selectively converted to ethylene glycol.14 The methyl group of p-toluenesulfonic acid is selectively oxidized to the corresponding alcohol and aldehyde.15 In spite of the simplicity of these systems, there is little recent work on them that shows promise for the development of preparative-scale processes.

Alkene Isomerization.

a,b-Unsaturated ketones can be isomerized to b,g-unsaturated ketones through the formation of a p-complex with Na2PtCl4 (eq 3).4 Analogous reaction with Na2PdCl4 gives a stable p-allyl complex (eq 4) (see Disodium Tetrachloropalladate(II)).16

1. (a) Gmelin Handbook of Inorganic Chemistry; Springer: Berlin 1986; Pt Suppl. Vol. A1, pp 299-308. (b) Hartley, F. R. The Chemistry of Platinum and Palladium; Wiley: New York, 1973. (c) Chemistry of the Platinum Group Metals; Hartley, F. R., Ed.; Elsevier: Amsterdam, 1991.
2. (a) Garnett, J. L.; Long, M. A. In Isotopes in the Physical and Biomedical Sciences; Buncel E.; Jones J. R., Eds; Elsevier: Amsterdam, 1987; Part A, Vol. 1, pp 86-121. (b) James, B. R. Homogeneous Hydrogenation; Wiley: New York, 1973.
3. (a) Shilov A. E. In Activation and Functionalization of Alkanes; Hill, C. L., Ed.; Wiley: New York, 1989; pp 1-26. (b) Shilov, A. E. Activation of Saturated Hydrocarbons by Transition Metal Complexes; Reidel: Dordrecht, 1984.
4. (a) Gillard, R. D.; Heaton, B. T.; Pilbrow, M. F. OPP 1974, 6, 131. (b) Gillard, R. D.; Heaton, B. T.; Pilbrow, M. F. JCS(A) 1970, 353.
5. (a) Garnett, J. L.; Kenyon, R. S. AJC 1974, 27, 1023. (b) Hodges, R. J.; Garnett, J. L. J. Catal. 1969, 13, 83.
6. Davis, K. P.; Garnett, J. L. AJC 1975, 28, 1713.
7. (a) Preece, M.; Robinson, S. D. ICA 1978, 29, L199. (b) Garnett, J. L.; Hodges, R. J. CC 1967, 1220.
8. Garnett, J. L.; O'Keefe, J. H. J. Labelled Comp. 1975, 11, 201.
9. Garnett, J. L.; Kenyon, R. S. JCS(D) 1971, 1227.
10. Garnett, J. L.; Hodges, R. J. JACS 1967, 89, 4547.
11. Garnett, J. L.; Long, M. A.; Than, C.; Williams, P. G. JCS(F) 1990, 86, 875.
12. Garnett, J. L.; Hodges, R. J. CC 1967, 1001.
13. Calf, G. E.; Garnett, J. L. TL 1973, 511.
14. Labinger, J. A.; Herring, A. M.; Bercaw, J. E.; JACS 1990, 112, 5628.
15. Labinger, J. A.; Herring, A. M.; Lyon, D. K.; Luinstra, G. A.; Bercaw, J. E.; Horvath, I. T.; Eller, K. OM 1993, 12, 895.
16. (a) Fong, C. W.; Kitching, W. AJC 1969, 22, 477. (b) Parshall, G. W.; Wilkinson, G. IC 1962, 1, 896.

Valeri Martichonok

University of Toronto, Ontario, Canada

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