Organoamidometallics. I. Syntheses of [N,N′-Bis(Polyfluorophenyl)Ethane-1,2-Diaminato(2-)]Platinum(II) Complexes by Decarboxylation

Abstract

Reaction of PtCl₂(en) (en = ethane-1,2-diamine) with thallous pentafluorobenzoate in hot pyridine ( py ) or 4-methylpyridine ( mepy ) yields the [N,N′- bis (2,3,5,6-tetrafluorophenyl)ethane-1,2-diaminato(2-)]platinum(II) complexes, Pt[N(p-HC₆F₄)CH₂]₂( py )₂ (1a) and Pt[N(p- HC₆F₄)CH₂]₂( mepy )₂ (1b). The route to (1a) is considered to involve formation of [Pt(en)( py )₂](O₂CC₆F₅)₂ (2), decarboxylation of (2) into Pt(NHCH₂)₂( py )₂ (1c) and pentafluorobenzene, and nucleophilic attack of (1c) on C₆F₅H. Complex (1a) has also been prepared by decarboxylation of (2), reaction of PtI₂(en) and TlO₂CC₆F₅, and reaction of PtCl₂(en), C₆F₅H, and TlO₂CC₆F₄H-p in boiling pyridine. From reaction of PtCl₂(en), TlO₂CC₆F₄H-p, and the appropriate polyfluorobenzene (RF) in boiling pyridine or 4-methylpyridine, the organoamidoplatinum compounds Pt(NRCH₂)₂L₂(R = C₆F₅, p-MeC₆F₄, p-ClC₆F₄, p-BrC₆F₄, p-IC₆F₄, 2,3,5-F₃C₆H₂, or p-C₆F₅C₆F₄, L = py and R = C₆F₅, L = mepy ) have been prepared. Analogous reactions of PtCl₂( pn )( pn = propane-1,3-diamine) give the complexes Pt[NR(CH₂)₃NR]( py )₂ (R = C₆F₅ or p-HC₆F₄). Spectroscopic evidence for the structures is discussed. The polyfluorophenyl groups confer stability to water on ethane-1,2-diaminato(2-)platinum(II) complexes, and this is attributable to delocalization of non-bonded lone pairs from the amido nitrogens into the polyfluorophenyl rings.