Reactions of [PhI(pyridine)₂]²⁺ with Model Pd and Pt II/IV Redox Couples

The results of the reactions of the dicationic iodine­(III) family of oxidants [PhI­(pyridine)₂]²⁺ with model Pd­(II) and Pt­(II) complexes are described. Depending on the specific reaction pairs, a variety of outcomes are observed. For palladium, Pd­(IV) complexes cannot be observed but are implicated in C–C and C–N bond formation for Pd­(II) starting materials based on phenylpyridine and 2,2-bipyridine, respectively. Theoretical comparisons with similar processes for −Cl and −OAc rather than pyridine indicate that these provide greater thermodynamic stability, and our results here show that they also give greater kinetic stability (the failure of MP2 methods for these systems is quite dramatic). In contrast, oxidation and delivery of the pyridine ligands gives dicationic Pt­(IV) complexes that may be isolated and structurally characterized

Facile Formation of Homoleptic Au(III) Trications via Simultaneous Oxidation and Ligand Delivery from [PhI(pyridine)₂]²⁺

We report the first examples of Au­(III) tricationic complexes bound only by neutral monodentate ligands, which are a new class of gold reagents. Oxidative addition to the bis-pyridine Au­(I) cation, [Au­(4-DMAP)₂]⁺, using a series of dicationic I­(III) oxidants of the general form [PhI­(L)₂]²⁺ (L = pyridine, 4-DMAP, 4-cyanopyridine) allows ready access to homoleptic and pseudo-homoleptic Au­(III) complexes [Au­(4-DMAP)₂(L)₂]³⁺. The facile oxidative addition of Au­(I) species additionally demonstrates the efficacy of PhI­(L)₂]²⁺ reagents as halide-free oxidants for Au­(I). Comparisons are made via attempts to oxidize NHC-Au­(I)­Cl, where introduction of the chloride anion results in complex mixtures via ligand and chloride exchange, demonstrating the advantage of using the pyridine-based homoleptic compounds. The new Au­(III) trications show intriguing reactivity with water, yielding dinuclear oxo-bridged and rare terminal Au­(III)−OH complexes

Access to the Parent Tetrakis(pyridine)gold(III) Trication, Facile Formation of Rare Au(III) Terminal Hydroxides, and Preliminary Studies of Biological Properties

In this paper we report on the use of [NO]­[BF₄] to access tricationic tetrakis­(pyridine)­gold­(III) from Au powder, a species inaccessible using the more traditional (tetrahydrothiophene)­AuCl route. It is then demonstrated that this family of compounds can be used to access new terminal Au­(III) hydroxides, a challenging class of compounds, and the first crystallographically characterized examples employing bidentate ligands. Finally, preliminary biological studies indicate good activity for derivatives featuring polydentate ligands against the HeLa and PC3 cell lines but also strong inhibition of primary HUVEC cells

Access to the Parent Tetrakis(pyridine)gold(III) Trication, Facile Formation of Rare Au(III) Terminal Hydroxides, and Preliminary Studies of Biological Properties

In this paper we report on the use of [NO]­[BF₄] to access tricationic tetrakis­(pyridine)­gold­(III) from Au powder, a species inaccessible using the more traditional (tetrahydrothiophene)­AuCl route. It is then demonstrated that this family of compounds can be used to access new terminal Au­(III) hydroxides, a challenging class of compounds, and the first crystallographically characterized examples employing bidentate ligands. Finally, preliminary biological studies indicate good activity for derivatives featuring polydentate ligands against the HeLa and PC3 cell lines but also strong inhibition of primary HUVEC cells