π‐ und ρ‐Komplexe aus Dimethylacetylen und Gold(III)‐chlorid als Vorstufen der Bildung von 3.4‐Dichlor‐tetramethyl‐cyclobuten

Abstract

Gold(ll1)-chlorid tritt mit unterschussigen bzw. aquivalenten Mengen Dimethylacetylen be;tiefen Temperaturen zu roten x-Komplexen (3 bzw. 4) zusammen, die sich in kurzer Zeit spontan in Gold(lI1)-a-Verbindungen (5 bzw. 6 ) mit der Anordnung 2-Chlor-I-methylpropenylgold-dichlorid urnlagern. Diese Gruppe liefert mit weiterem, iiberschiissigen Dimethylacetylen das 3.4-Dichlor-l.2.3.4-tetramethyl-cyclobuten-(l) (2), wobei das a-gebundene Gold zur einwertigen Stufe reduziert wird. Das andere isolierbare Endprodukt dieser Umsetzung ist der schon bekannte x-Komplex Bis(dimethy1acetylen)-gold(1)-tetrachloroaurat (1). x-and a-Complexes from Dimethylacetylene and Gold(III) Chloride as Intermediates for the Formation of 3.4-DichlorotetramethylcyclobuteneAt low temperatures gold(Il1) chloride with deficient or equivalent amounts of dimethylacetylene forms red x-complexes (3 or 4) which, after a short time, spontaneously rearrange to gold(II1) o-compounds (5 or 6), containing the 2-chloro-1-methylpropenylgold dichloride group. With an excess of dimethylacetylene this group reacts to give 3.4-dichloro-l.2.3.4-tetramethyl-1-cyclobutene (2). In the course of this reaction the a-bonded gold is reduced to gold@), which can be isolated as the known x-complex bis(dimethylacetylene)gold(I) tetrachloroaureate (1). HVor kurzem konnten wir uber die Darstellung von Goldkomplexen disubstituierter Acetylene berichten 2). Wahrend Gold( I)-chlorid bei unter 0" in einfacher Addition x-Komplexe des Typs R-CYC-R R = CH3, CzH,, CcH,

Reactivity of 5-alkynyl-3,4-dihydro-2H-pyrroles with Au(III): Route to vinylgold(III) complexes, aurocycles by cyclisation of these complexes and ML complexes

“…A diene-diylgold(III) complex prepared by Helaja et al (13) has been obtained by H migration. One can also notice that the AuCl3 addition on dimethylacetylen was previously reported and discussed by R. Hüttel and H. Forkl (14).…”

Gold η2-Coordination to Unsaturated and Aromatic Hydrocarbons: The Key Step in Gold-Catalyzed Organic Transformations

“…However, most of the compounds obtained were of very limited stability and decomposed at or below room temperature, except for adducts of strained (cyclic) olefins. It also appeared that gold(I) halides formed the more stable complexes compared to gold(III) congeners with the same olefin. − …”

Isolable Tris(alkyne) and Bis(alkyne) Complexes of Gold(I)

“…[14][15][16][17] In contrast, molecules with more than one p-bonded alkyne moiety on gold are extremely rare. [26] Herein, we present the synthesis, spectroscopy, and first structural details of a tris(alkyne) and a bis-(alkyne) gold complex, [(coct) 3 Au][SbF 6 ] and [Au(coct) 2 Cl] (Scheme 1). [18][19][20][21][22][23][24] Wittig and Fischer reported a gold p alkyne complex [Au(coct) 2 Br] in 1972 (coct = cyclooctyne) featuring two alkyne units on a gold center, but structural data are not available.…”

“…[25] Hüttel and Forkl also reported some gold adducts possibly involving more than one simple alkyne unit on gold, but the compounds were thermally unstable and poorly characterized. [26] Herein, we present the synthesis, spectroscopy, and first structural details of a tris(alkyne) and a bis-(alkyne) gold complex, [(coct) 3 Au][SbF 6 ] and [Au(coct) 2 Cl] (Scheme 1). Optimized geometries of [(coct) 3 Au] + and [Au-(coct) 2 Cl] using density functional theory (DFT) at the BP86/ def2-TZVPP level of theory and a detailed analysis of the gold-alkyne bonding interactions are also presented.…”