Generation and Structural Characterization of a Gold(III) Alkene Complex

Abstract

Gold: Ein AuIII‐Alken‐Komplex wurde hergestellt und NMR‐spektroskopisch und röntgenkristallographisch charakterisiert. Die Bindungseigenschaften wurden mit theoretischen Methoden untersucht. Die ungleichen Bindungslängen in [(cod)AuMe2]+ resultieren daraus, dass die Präferenz des 1,5‐Cyclooctadiens (cod) für nichtparallele Doppelbindungen die Rückbindung durch das Metall, die eine parallele Doppelbindung begünstigt, überwiegt.

Gold(III)‐Mediated Contraction of Benzene to Cyclopentadiene: From p‐Benziporphyrin to Gold(III) True Tetraarylcarbaporphyrin

“…for a metalalkene complex (cod = cyclooctadiene; BARF À = [(3,5-(CF 3 ) 2 C 6 H 3 ) 4 B] À ). [22] The set of Wiberg bond indices [32] ( Table 1) (Figure 7), a result that is consistent with the detected electrophilicity toward alkoxides. The majority of the carbon atoms of 7 b gain a positive charge because gold(III) coordination provides a suitable incentive for activation of the macrocycle in the reported transformations.…”

“…The trianionic macrocyclic core of 5 favorably matches the formal oxidation state of gold(III), whereas coordination of pal- Figure 3) [24] resembles the structure of gold(III) 5,10,15,20-tetrarylporphyrin [25] and 5,10,15,20-tetraryl N-confused porphyrin. [26] The coordination environment of the gold(III) center corresponds to the square-planar structure with the N (22), N(23), N(24), and C(21) atoms occupying equatorial positions. The macrocycle reveals the bond-length pattern expected for the aromatic free base, 5,10,15,20-tetraaryl-21-carbaporphyrin.…”

“…[17,18,21] At present, relatively little is understood considering the real active catalytic species, [18][19][20] but, herein, a gold(III) p-bonding interaction is instrumental for contraction, an interaction that is frequently postulated as an essential step. [18,22,23] Although the present work has allowed the first Scheme 5. Suggested mechanism of gold(III)-mediated transformations.…”

“…The choice of metal cation is strongly motivated by the rising interest in reactions catalyzed by gold nanoparticles and gold(I) or gold(III) compounds. [16][17][18][19][20][21][22][23] Herein, we report on the formation and characterization of gold(III) 21-carbaporphyrin, in which the CNNN coordination cavity comprises four trigonally hybridized donor atoms.…”

Gold(I) Complexes of Phosphaalkynes

“…This suggestion is reinforced by recent theoretical results from Tilset and co‐workers, who studied the degree of backbonding in the gold(III) alkene complex [(cod)AuMe 2 ][BAr F ] and compared it to that of the neutral Pt II complex. They found that the metal d xz and d yz orbitals backdonated into the π* orbital of the alkene, but the contribution was weaker, though still significant, in the gold(III) complex 16…”