RESUMO
Treatment of NHC-AuCl (NHC = IPr and IMes) complexes with equimolar amounts of KTpR2 (R = Me, H) salts in tetrahydrofuran produces in high yields the heteroleptic complexes 3-6 with the general formula NHC-Au-TpR2. As the TpR ligand in complexes 3-6 features a k1-N type coordination toward the gold(i) center, the subsequent addition of group 10 and 11 metal precursors (NiII, PtII, CuII) results in the isolation of heterobimetallic Au/M complexes supported by TpR platforms. All new metal complexes have been fully characterized by elemental analysis and NMR spectroscopy, and in the case of 3, 4 and 6 by X-ray crystallography.
RESUMO
We report the preparation and full characterization of a series of hydroxyl functionalized 1,2,3-triazolylidene-based PEPPSI complexes 2a-c and their catalytic application in the Suzuki cross coupling reaction of aryl chlorides/amides with boronic acids. Under basic reaction conditions, complexes 2a-c show a notable increase in their catalytic efficiency compared with two ether-wingtip functionalized PEPPSI analogues (3 and 4) and a commercially available NHC-Pd complex (5). The catalytic results suggest that deprotonation of the hydroxyl group in complexes 2a-c plays an important role in the overall process. Deprotonation of the alcohol moiety of complexes 2a-b with sodium tert-butoxide allows for the isolation of metallacycles 6a-b, which are proposed as the active species of cross coupling reactions.
RESUMO
Reaction of triazolium precursors [MIC(CH2 )n - H+ ]I- (n=1-3) with potassium hexamethyldisilazane (KHMDS) and AuCl(SMe2 ) generates the gold(I) complexes of the type MIC(CH2 )n â AuI. Visible light exposure of the latter complexes promotes a spontaneous disproportionation process rendering gold(III) complexes of the type [{MIC(CH2 )n }2 â AuI2 ]+ I- . Both the AuI and AuIII complex series were tested in the catalytic hydrohydrazination of terminal alkynes using hydrazine as nitrogen source.
