Hydrogen Bonding in Platinum Indolylphosphine Polyfluorido and Fluorido Complexes

Abstract

The reaction of the Pt complexes cis-[Pt(CH3)(Ar){Ph2P(Ind)}2] (Ind=2-(3-methyl)indolyl, Ar=4-tBuC6H4 (1 a), 4-CH3C6H4 (1 b), Ph (1 c), 4-FC6H4 (1 d), 4-ClC6H4 (1 e), 4-CF3C6H4 (1 f)) with HF afforded the polyfluorido complexes trans-[Pt(F(HF)2)(Ar){Ph2P(Ind)}2] 2 a–f, which can be converted into the fluoride derivatives trans-[Pt(F)(Ar){Ph2P(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 |1J(F,Pt)|, but lower 1J(H,F) coupling constants when compared to the fluorido complexes 3 a–f. Decreasing 1J(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-tBuC6H4 (a) ≈4-CH3C6H4 (b) <4-ClC6H4 (e)<4-CF3C6H4 (f). In addition, the larger cis influence of aryl ligands bearing electron-withdrawing groups in the para position correlates with decreasing magnitudes of |1J(F,Pt)| coupling constants. The interpretation of the experimental data was supported by quantum-chemical DFT calculations.