Übergangsmetall—methylen-komplexe

Gem-Diaurated Gold(III) Complexes: Synthesis, Structure, Aurophilic Interaction, and Catalytic Activity

We present a protocol to synthesize air stable gem-diaurated gold(III) compounds from 1,3-diketones in a single cycloauration step with tetrachloroauric acid. So far related species were only accessible from phosphonium bis(ylide) ligands which hold the two gold atoms in close proximity. Lacking such a constraint, our compounds show the longest Au-Au distances of all gem-diaurated carbons, ranging from 3.26 to 3.32 Å. Modeling based on results of CCSD(T) calculations shows no stabilization by aurophilic interactions for our gold(III) systems, compared to 9.1 kcal/mol for gold(I) gem-diauration. This demonstrates no aurophilic interactions are needed for the isolation of air stable gem-diaurated gold(III) complexes. We show the new gem-diaurated gold(III) compounds are active in the gold-catalyzed phenol synthesis and highly active in the cycloisomerization of an N-propargylcarboxamide; here, we obtained the so far highest known TON of over 2500 per gold atom with respect to the oxazole formation.

[μ-1,3-Dioxo-1,3-bis(pyridin-2-yl)propane-2,2-diido-κN,C:κC,N']bis[(1,3-diphenylpropane-1,3-dionato-κO,O')palladium(II)](Pd-Pd)

The title compound, [Pd₂(C₁₃H₈N₂O₂)(C₁₅H₁₁O₂)₂], crystallized from a mixture of ethanol and n-hexa­nes. The structure is the first example of β-diketonate in a dianionic κ²C-coordination complex containing a Pd^II—Pd^II bond. Both Pd^II atoms adopt a pseudo square-planar coordination geometry. The mol­ecular packing involves π-inter­actions between the phenyl rings of the 1,3-diphenyl­propane-1,3-dionato ligands with centroid–centroid distances in the range 3.823 (2)–3.868 (2) Å.