Air‐Stable Cationic Gold(I) Catalyst Featuring a Z‐Type Ligand: Promoting Enyne Cyclizations

Abstract

An air-stable cationic Au(I) complex featuring a Z-type ligand (boron atom) as a σ-acceptor was developed for elucidating the effect of B on catalytic reactions. An enyne cyclization in the presence of either [Au→B](+) or [Au](+) showed that [Au→B](+) promotes the reactivity, which enabled the effective construction of not only five- and six-membered rings, but also seven-membered rings.

Coordination and Redox Non-innocent Behavior of Hybrid Ligands Containing Tellurium

“…These geometric and spectroscopic changes can be attributed to the increased donicity of the tellurium center towards the platinum center as a response to a more electron-deficient platinum center and the tighter chloride coordination to the tellurium center. NBO analyses performed on the DFT-optimized geometries of [11] + and 12 further corroborate this effect ( Figure 6). Although natural localized molecular orbitals (NLMOs) are found in both cases, inspection of the atomic contributions ( [11] + : 57% Te/39% Pt, 12: 35% Te/63% Pt) shows that the increased Lewis acidity of the platinum center and the stronger chloride binding at tellurium induces a sizeable shift in bond polarity towards the platinum center.…”

“…NBO analyses performed on the DFT-optimized geometries of [11] + and 12 further corroborate this effect ( Figure 6). Although natural localized molecular orbitals (NLMOs) are found in both cases, inspection of the atomic contributions ( [11] + : 57% Te/39% Pt, 12: 35% Te/63% Pt) shows that the increased Lewis acidity of the platinum center and the stronger chloride binding at tellurium induces a sizeable shift in bond polarity towards the platinum center. A similar effect has been observed by Puddephatt in a oxidative addition product of Ph 2 TeCl 2 to Me 2 Pt(bu 2 bpy) (bu 2 bpy: 4,4¤-di-tertbutyl-2,2¤-bipyridine) (13-Cl, Scheme 5).…”

“…The reduced quantum yield of 12 relative to superior platforms such as C and D may be reconciled by inspection of their NBO-derived TePt NLMOs (vide supra). As the atomic contributions to the TePt NLMOs ( [11] + : 57% Te/39% Pt, 12: 35% Te/63% Pt) suggest, incorporation of a chloride anion into the coordination sphere of tellurium upon oxidation of the platinum center induces an umpolung of the Te Pt bond. By assuming a hypervalent configuration, the tellurium center becomes a stronger donor by virtue of an "anion-push/ platinum-pull" effect ( Figure 12).…”

An Antimony(V) Dication as a Z‐Type Ligand: Turning on Styrene Activation at Gold

“…[5a] To confirm that these two isomers differ in the way they interact with the chloride counterions,w et reated [12] TheA u-Sb bond lengths of 2.613 (7) (7) in [3][NTf 2 ] 2 are significantly shorter than in 1 (2.709 (9) ), thus indicating as trengthening of the Au-Sb interaction triggered by the increased Lewis acidity of the antimony center. This square-planar geometry is consistent with the strong donation of ag old d-orbital electron pair to antimony,l eading to an electronic configuration that approaches that of ac lassical d 8 metal center.I nt he case of [2a] [Cl],the square-planar gold atom is capped by achloride ligand that forms al ong Au-Cl interaction of 2.910 (2) .A natural bond orbital (NBO) analysis of [3] 2+ affords abonding description in which ad icationic triarylantimony unit is stabilized intramolecularly by donation from the phosphine oxide functionality and from the metallobasic gold atom. This square-planar geometry is consistent with the strong donation of ag old d-orbital electron pair to antimony,l eading to an electronic configuration that approaches that of ac lassical d 8 metal center.I nt he case of [2a] [Cl],the square-planar gold atom is capped by achloride ligand that forms al ong Au-Cl interaction of 2.910 (2) .A natural bond orbital (NBO) analysis of [3] 2+ affords abonding description in which ad icationic triarylantimony unit is stabilized intramolecularly by donation from the phosphine oxide functionality and from the metallobasic gold atom.…”

Substrate Specific Silver(I)-Catalyzed Cycloisomerization of Diene Involving Alkyl Rearrangements: Syntheses of 1,2,5,6-Tetrahydrocuminic Acid, <i>p</i>-Menth-3-en-7-ol, and <i>p</i>-Menth-3-en-7-al

“…silver, 31,32) and copper, 33,34) have led to various types of reactions. In comparison with the catalytic reaction using a triple bond, the silver catalyzed reactions of simple alkene moieties are limited.…”