Platinum Indolylphosphine Fluorido and Polyfluorido Complexes: An Interplay between Cyclometallation, Fluoride Migration, and Hydrogen Bonding

The reaction of [PtCl2(COD)] (COD=1,5‐cyclooctadiene) with diisopropyl‐2‐(3‐methyl)indolylphosphine (iPr2P(C9H8N)) led to the formation of the platinum(ii) chlorido complexes, cis‐[PtCl2{iPr2P(C9H8N)}2] (1) and trans‐[PtCl2{iPr2P(C9H8N)}2] (2). The cis‐complex 1 reacted with NEt3 yielding the complex cis‐[PtCl{κ2‐(P,N)‐iPr2P(C9H7N)}{iPr2P(C9H8N)}] (3) bearing a cyclometalated κ2‐(P,N)‐phosphine ligand, while the isomer 2 with a trans‐configuration did not show any reactivity towards NEt3. Treatment of 1 or 3 with (CH3)4NF (TMAF) resulted in the formation of the twofold cyclometalated complex cis‐[Pt{κ2‐(P,N)‐iPr2P(C9H7N)}2] (4). The molecular structures of the complexes 1–4 were determined by single‐crystal X‐ray diffraction. The fluorido complex cis‐[PtF{κ2‐(P,N)‐iPr2P(C9H7N)}{iPr2P(C9H8N)}] ⋅ (HF)4 (5 ⋅ (HF)4) was formed when complex 4 was treated with different hydrogen fluoride sources. The Pt(ii) fluorido complex 5 ⋅ (HF)4 exhibits intramolecular hydrogen bonding in its outer coordination sphere between the fluorido ligand and the NH group of the 3‐methylindolyl moiety. In contrast to its chlorido analogue 3, complex 5 ⋅ (HF)4 reacted with CO or the ynamide 1‐(2‐phenylethynyl)‐2‐pyrrolidinone to yield the complexes trans‐[Pt(CO){κ2‐(P,C)‐iPr2P(C9H7NCO)}{iPr2P(C9H8N)}][F(HF)4] (7) and a complex, which we suggest to be cis‐[Pt{C=C(Ph)OCN(C3H6)}{κ2‐(P,N)‐iPr2P(C9H7N)}{iPr2P(C9H8N)}][F(HF)4] (9), respectively. The structure of 9 was assigned on the basis of DFT calculations as well as NMR and IR data. Hydrogen bonding of HF and NH to fluoride was proven to be crucial for the existence of 7 and 9. Fluorine on Skatole's scent. Tetramethylammoniumfluoride permits the twofold cyclometallation of 3‐methyl‐2‐indolylphosphine ligands at platinum(ii) complexes. Hydrogen fluoride opens the cyclometallation yielding a unique Pt(ii) complex which exhibits hydrogen‐bonding to the fluorido ligand in its outer coordination sphere. The fluorido complex reacts with an ynamide to give an exceptional metal bound oxazole derivative.