Synthesis and characterization of chelate and bridging triazenide complexes of palladium and platinum. Stereoselective oxidative addition of chlorine or iodine to [NBu4][Pt(C6F5)2(η2-PhNNNPh)]

Abstract

The triazenide complexes cis-[M(C₆F₅)₂(η²-ArNNNAr)] ⁻ (M = Pd, Pt; Ar = C₆H₅, C₆H₄Me-p), anti-[{Pd(C₆F₅)(L)(μ-PhNNNPh)}₂] [L = PPh₃, t-BuNC, PhCN, tht (tht = SC₄H₈, tetrahydrothiophene)] and anti-[{Pd(C₆F₅)(Br)(μ-PhNNNPh)}₂]²⁻ have been prepared by treatment of the corresponding precursors [{M(C₆F₅)₂(μ-OH)}₂]²⁻ (M = Pd, Pt), [{Pd(C₆F₅)(L)(μ-X)}₂] (X = OH or Cl) and [{Pd(C₆F₅)(Br)(μ-Br)}₂]²⁻ with either ArNNNHAr or ArNNNAr⁻. The stereoselective oxidation of cis-[Pt(C₆F₅)₂(PhNNNPh)]⁻ with PhICl₂ or I₂ leads to the synthesis of the corresponding mononuclear platinum(IV) complex cis,trans-[Pt(C₆F₅)₂(PhNNNPh)(X)₂]⁻ (X = Cl or I). The crystal structures of cis-[Pd(C₆F₅)₂(η²-PhNNNPh)]⁻, anti-[{Pd(C₆F₅)(t-BuNC)(μ-PhNNNPh)}₂] and cis,trans-[Pt(C₆F₅)₂(η²-PhNNNPh)(Cl)₂]⁻ have been established by X-ray diffraction. The Pd⋯Pd distance bridged by the rigid triazenido ligands in anti-[{Pd(C₆F₅)(t-BuNC)(μ-PhNNNPh)}₂] is 2.9907(8) Å where a boat conformation of the central ‘Pd₂N₆’ eight-membered ring is observed. The [Pt(C₆F₅)₂(η²-PhNNNPh)(Cl)₂]⁻ anion shows an octahedral arrangement around the platinum atom, involving two trans-chloro ligands, two cis-C₆F₅ groups and a chelating triazenide.