Olefin‐Gold‐Komplexe, VIII. Cyclooctatetraen‐Goldchlorid‐Komplexe

Abstract

Zwei Goldkomplexe des Cyclooctatetraens (COT), COT .AuCI und COT .Au2C14, werden dargestellt und ihre Eigenschaften beschrieben. Die Erwartung, daR COT mit AuCI3 in gleicher Weise wie mit SbCIs zum 8-Chlorhomotropylium-Salz reagieren wiirde, hat sich nicht bestatigt.Olefin Gold Complexes, yIIL1) Cyclaoctatetraene Gold Chloride Complexes Two complexes of COT with gold, COT .AuCI and COT .Au~C14. were synthesized and their properties are described. The reaction of COT with AuCl3 did not deliver the expected 8-chlorohomotropylium salt. (n + 1) Olefin + 2 AuC13 ----+ Olefindichlorid + (Olefin),.Au2C14 n = 1-3 2) Bisher nur beim Hexamethyl-Dewar-Benzol (HMDB) wurde beobachtet, daR die Chlorierungsreaktion auch bei einem Chlorcarbenium-Ion stehenbleiben kann, das mit AuC14-zu einem stabilen Salz zusammentritt, wahrend das entstandene AuCl sich mit (uberschiissigem) HMDB zum Komplex Olefin.AuC1 vereinigtl):

Structurally Characterized Coinage‐Metal–Ethylene Complexes

“…Early work on gold-alkene adducts mainly involves (alkene)AuCl type complexes. [134][135][136][137][138][139][140][141][142][143] These adducts tend to have poor thermal and solution stabilities. Recently, Cinellu and co-workers reported NMR spectroscopic data for several cationic goldethylene adducts supported by 6-substituted-2,2Ј-bipyridines.…”

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. − …”

“…Structural information was finally first obtained in 1987 on one of Hüttel’s compounds by the group of J. Strähle in Tübingen in a collaboration with F. Calderazzo’s group in Pisa for ( cis -cyclooctene)AuCl ( 5 ), which features Au−C distances of 2.15(2) and 2.21(2) Å, while the CC distance of 1.38(2) Å is significantly longer than in the free olefin ligand (1.332(2) Å) . In the IR spectrum of this first structurally well-defined complex the ν(CC) stretching vibration is observed at 1525 cm −1 , well below the 1648 cm −1 reported for the free olefin, a feature common to the vibrational spectra of all olefin complexes of gold(I) already noted by Chalk, Hüttel, and others in most of the earlier work. − Conversely, the absence of a similar shift in the ν(CC) absorption to smaller wavenumbers in organogold compounds with “dangling” vinyl or allyl groups (as in Ph 3 PAuC 6 H 4 -2-CHCH 2 or Ph 3 PAuC 6 H 4 -2-CH 2 CHCH 2 with ν(CC) 1615 and 1638 cm −1 , respectively) was taken as a proof for the absence of any (olefin)gold coordination . The new structural results have been important benchmark data for subsequent theoretical investigations of (olefin)AuX complexes.…”

“…It also appeared that gold(I) halides formed the more stable complexes compared to gold(III) congeners with the same olefin. [22][23][24][25][26][27][28][29][30][31] In early work, the complexes were identified mainly by elemental analysis, vibrational spectroscopy, and cryoscopic or osmometric molecular mass determinations. 29 A few complementary experiments were carried out in several laboratories, 32 including those of G. Wittig 33 and G. J. M. van der Kerk, 34 focusing on complexes with 1,5-cyclooctadiene, cyclooctyne, and styrene, respectively, but this work obviously was soon discontinued.…”

Thermally Stable Gold(I) Ethylene Adducts: [(HB{3,5‐(CF3)2Pz}3)Au(CH2CH2)] and [(HB{3‐(CF3),5‐(Ph)Pz}3)Au(CH2CH2)]

“…However with gold(I), even complexes of substituted olefins are quite limited, and structurally characterized ethylene adducts are unknown. [3,4,[24][25][26][27][28][29][30][31][32][33][34][35][36] Herein, we report the synthesis and X-ray crystal structures of two remarkably stable gold(I) ethylene complexes ( Figure 1) that are easily obtained by using tris(pyrazolyl)borates [HB{3,5-(CF 3 ) 2 Pz} 3 ] À (where [HB{3,5-(CF 3 ) 2 Pz} 3 ] = hydrotris(3,5-bis(trifluoromethyl)pyrazolyl)borate) and [HB(3-(CF 3 ),5-(Ph)Pz) 3 ] À as supporting ligands. [37][38][39] The treatment of [HB{3,5-(CF 3 ) 2 Pz} 3 ]Na with gold(I) chloride under an ethylene atmosphere led to the gold(I) ethylene complex [(HB{3,5-(CF 3 ) 2 Pz} 3 )Au(C 2 H 4 )] (1) in good yield.…”