Synthesis and Site-selective Protonation of MoPt and WPt Bimetallic Complexes

DOI: 10.1039/DT9920002793

Source and publish data:

Journal of the Chemical Society, Dalton Transactions p. 2793 - 2802 (1992)

Update date:2022-08-05

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Authors:

Powell, John

Sawyer, Jeffery F.

Smith, Stuart J.

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Article abstract of DOI:10.1039/DT9920002793

The reaction of PF6 1 (M = Mo or W, cp = η-C6H5) with proceeds rapidly with a 1:2 (M:Pt) stoichiometry to give <(OC)2(cp)M(μ-PPh2)Pt(CO)(PPh3)> 4 and PF6 5.However, using an initial 1:1 stoichiometry the final product is <(OC)2(cp)M(μ-H)(μ-PPh2)Pt(PPh3)2>PF6 8.The mechanisms of these reactions are shown to involve deprotonation of 1 to give <(OC)3M(cp)(PPh2)> 2 followed by reaction of the latter with and subsequent transfer of CO from M to Pt to give 4.Protonation of 4 with HBF4 is metal (M) dependent and proceeds to give <(OC)2(cp)Mo(μ-H)(μ-PPh2)Pt(CO)(PPh3)>BF4 12a with M = Mo but for M = W the major product is <(OC)2H(cp)W(μ-PPh2)Pt(CO)(PPh3)>BF4 13b.Variable-temperature (1)H NMR studies show that the terminal hydride cation of 13b is rapidly equilibrating with a small amount of the hydride-bridged isomeric cation <(OC)2(cp)W(μ-H)(μ-PPh2)Pt(CO)(PPh3)>(1+).Complex 4 reacts with PPh3 (60 deg C) and 1,2-bis(diphenylphosphino)ethane (dppe) at 20 deg C to give <(OC)2(CP)M(μ-PPh2)Pt(PPh3)2> 9 and <(OC)2(cp)M(μ-PPh2)Pt(dppe)> 10.On bubbling CO through a solution of 9 (20 deg C) complex 4 is rapidly regenerated.Reaction of 4 with HCl gives <(OC)2(cp)M(μ-H)(μ-PPh2)PtCl(PPh3)> 15.The molecular structure of <(OC)2(cp)W(μ-PPh2)Pt(CO)(PPh3)> 4b has been determined by single-crystal X-ray diffraction.