Dialkylbiarylphosphine Complexes of Gold(I) Halides. Gold−Aryl π-Interactions in the Solid State

Abstract

Dialkylbiarylphosphines are an emerging ligand set that promote catalytic reactions of electrophilic late transition-element centers through dative interactions of the biaryl arm with the metal site. Presented here are syntheses and crystal structures of five new (dicyclohexylbiarylphosphine)gold(I) chlorides and bromides. X-ray diffraction crystallography reveals close approaches between gold(I) and the flanking ipso carbon (mean Au-C ipso distance, compounds 2-6: 3.156 Å). New compounds have been characterized by multinuclear NMR spectroscopy, X-ray diffraction crystallography, and combustion analysis.

Surveying the {AuCl} adducts of bulky phosphines bearing the 2,6-dimesitylphenyl group

“…Within the major isomer the closest AuÁ Á ÁC contact is 3.14 Å. The Au-P distance of 2.222(1) Å is consistent with reported Au-P distances for bulky R 3 PAuCl complexes [7]. The results of the structural determination of [(DmpPMe 2 )AuCl] (5) is shown in Fig.…”

“…Relative to the free phosphine and upon gold adduct formation, the observed 31 P chemical shift is substantially downfield (>30 ppm) for 5, but substantially upfield (>30 ppm) for 4 and 6. A simple inductive effect explains this behavior for 5, a pattern which has been repeatedly observed in the coordination chemistry of gold adducts of bulky, phosphorus containing ligands [7]. The 31 P NMR spectrum of 7 showed a triplet at d 213.3 ppm ( 1 J PF = 1170 Hz) in CDCl 3 .…”

“…Having two ortho-mesityl groups on each phosphine ensures the opportunity for each gold atom to engage in additional short AuÁ Á Áarene contacts, reminiscent of those postulated as being involved in low coordinate palladium chemistry. Short AuÁ Á Áarene contacts have often been noted in gold phosphine complexes [7][8][9]. In addition, other modes of reactivity are possible for halophosphines.…”

New and Easily Accessible Nitrogen Acyclic Gold(I) Carbenes: Structure and Application in the Gold‐Catalyzed Phenol Synthesis as well as the Hydration of Alkynes

“…The significant influence of the substituents on nitrogen on the activity and selectivity in the NAC is visible in the huge differences between some of the entries 2-22, especially 2c and 2h in entries 4 and 9; 2c is quite instable in solution, for example in chloroform it de- composes completely within 16 h. The activities and yields of 2a, 2b and 2d were superior to that of the IPrAuCl pre-catalyst (entry 23), which here also was investigated in the reaction with 4 for the first time. With the corresponding Buchwald ligand MePhos [29] (entry 24 and Figure 9) or PPh 3 (entry 25) much lower yields and TONs were obtained and the conversions were much slower.…”

Gold in Homogeneous Catalysis

“…30, 31 Related complexes (2c -d) with weakly coordinated bis(trifluoromethanesulfonyl)amide NTf 2 (Tf = CF 3 SO 2 ) have also been prepared. 32 Gold(I) complex (4) bearing the bulky ligand tris(2,6-di-tertbutylphenyl)phosphite leads to a highly electrophilic cationic Au(I) catalyst in situ by chloride abstraction with AgSbF 6 .…”