Fluoroalkylation of a Methylplatinum(II) Complex under Photoirradiation

Hydrogen Bonding in Platinum Indolylphosphine Polyfluorido and Fluorido Complexes

The reaction of the Pt complexes cis-[Pt(CH3 )(Ar){Ph2 P(Ind)}2 ] (Ind=2-(3-methyl)indolyl, Ar=4-tBuC6 H4 (1 a), 4-CH3 C6 H4 (1 b), Ph (1 c), 4-FC6 H4 (1 d), 4-ClC6 H4 (1 e), 4-CF3 C6 H4 (1 f)) with HF afforded the polyfluorido complexes trans-[Pt(F(HF)2 )(Ar){Ph2 P(Ind)}2 ] 2 a-f, which can be converted into the fluoride derivatives trans-[Pt(F)(Ar){Ph2 P(Ind)}2 ] (3 a-f) by treatment with CsF. The compounds 2 a-f and 3 a-f were characterised thoroughly by multinuclear NMR spectroscopy. The data reveal hydrogen bonding of the fluorido ligand with HF molecules and the indolylphosphine ligand. Polyfluorido complexes 2 a-f show larger |1 J(F,Pt)|, but lower 1 J(H,F) coupling constants when compared to the fluorido complexes 3 a-f. Decreasing 1 J(P,Pt) coupling constants in 2 a-f and 3 a-f suggest a cis influence of the aryl ligands in the following order: 4-tBuC6 H4 (a) ≈4-CH3 C6 H4 (b) Collapse

Key Words

• fluorido complexes
• hydrogen bonding
• indolylphosphine
• platinum
• polyfluorido complexes

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MESH Headings Collapse

Grants

• 387284271 - SFB 1349 Deutsche Forschungsgemeinschaft
• Deutsche Forschungsgemeinschaft

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Affiliation(s)

Stefan Sander Department of ChemistryHumboldt-Universität zu BerlinBrook-Taylor-Str. 212489BerlinGermany
Elizabeth J. Cosgrove Department of ChemistryHumboldt-Universität zu BerlinBrook-Taylor-Str. 212489BerlinGermany
Robert Müller Institut für ChemieTechnische Universität Berlin, Theoretische Chemie/Quantenchemie, Sekr.C7Straße des 17. Juni 13510623BerlinGermany
Martin Kaupp Institut für ChemieTechnische Universität Berlin, Theoretische Chemie/Quantenchemie, Sekr.C7Straße des 17. Juni 13510623BerlinGermany
Thomas Braun Department of ChemistryHumboldt-Universität zu BerlinBrook-Taylor-Str. 212489BerlinGermany

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Ligand-Mediated C-Br Oxidative Addition to Cycloplatinated(II) Complexes and Benzyl-Me C-C Bond Reductive Elimination from a Cycloplatinated(IV) Complex

Reaction of the Pt(II) complexes [PtMe₂(pbt)], 1a, (pbt = 2-(2-pyridyl)benzothiazole) and [PtMe(C^N)(PPh₂Me)] [C^N = deprotonated 2-phenylpyridine (ppy), 1b, or deprotonated benzo[h]quinoline (bhq), 1c] with benzyl bromide, PhCH₂Br, is studied. The reaction of 1a with PhCH₂Br gave the Pt(IV) product complex [PtBr(CH₂Ph)Me₂(pbt)]. The major trans isomer is formed in a trans oxidative addition (2a), while the minor cis products (2a' and 2a″) resulted from an isomerization process. A solution of Pt(II) complex 1a in the presence of benzyl bromide in toluene at 70 °C after 7 days gradually gave the dibromo Pt(IV) complex [Pt(Br)₂Me₂(pbt)], 4a, as determined by NMR spectroscopy and single-crystal XRD. The reaction of complexes 1b and 1c with PhCH₂Br gave the Pt(IV) complexes [PtMeBr(CH₂Ph)(C^N)(PPh₂Me)] (C^N = ppy; 2b; C^N = bhq, 2c), in which the phosphine and benzyl ligands are trans. Multinuclear NMR spectroscopy ruled out other isomers. Attempts to grow crystals of the cycloplatinated(IV) complex 2b yielded a previously reported Pt(II) complex [PtBr(ppy)(PPh₂Me)], 3b, presumably from reductive elimination of ethylbenzene. UV-vis spectroscopy was used to study the kinetics of reaction of Pt(II) complexes 1a-1c with benzyl bromide. The data are consistent with a second-order S_N2 mechanism and the first order in both the Pt complex and PhCH₂Br. The rate of reaction decreases along the series 1a ≫ 1c > 1b. Density functional theory calculations were carried out to support experimental findings and understand the formation of isomers.

1,5-Cyclooctadienyl alcohols and ketones generate a new class of COD Pt complexes

A variety of new racemic alcohol and ketone cyclooctadiene derivatives was prepared for their complexation with platinum to generate a new class of platinum(ii) complexes.