Synthesis, structural and photophysical properties of dimethylphosphino(perfluoro-)phenylene-based gold(I) dimers

Starting with 1,2-dibromobenzene and 1,2,3,4-tetrafluorobenzene, dimethyl(2-(trimethylstannyl)phenyl)phosphane, Me₂P(o-C₆H₄)SnMe₃, and dimethyl-[2,3,4,5-tetrafluoro-6-(trimethylstannyl)phenyl]phosphane, Me₂P(o-C₆F₄)SnMe₃, were synthesized and used in tin-gold exchange reactions to prepare two gold(I) dimers, bis[(2-dimethylphosphino)phenyl]di-gold(I), [Au₂(μ-2-C₆H₄PMe₂)₂], and bis[(2-dimethylphosphino)-3,4,5,6-tetrafluorophenyl]di-gold(I), [Au₂(μ-2-C₆F₄PMe₂)₂], respectively. Both tin precursor molecules, as well as the gold(I) complexes, were characterized by multinuclear NMR spectroscopy, CHN analysis and X-ray diffraction experiments. Both gold(I) dimers were further investigated by the means of computational as well as photophysical methods.

Gold(I) Phosphine Derivatives with Improved Selectivity as Topically Active Drug Leads to Overcome 5-Nitroheterocyclic Drug Resistance in Trichomonas vaginalis

Trichomonas vaginalis causes the most common, nonviral sexually transmitted infection. Only metronidazole (Mz) and tinidazole are approved for treating trichomoniasis, yet resistance is a clinical problem. The gold(I) complex, auranofin, is active against T. vaginalis and other protozoa but has significant human toxicity. In a systematic structure-activity exploration, we show here that diversification of gold(I) complexes, particularly as halides with simple C1-C3 trialkyl phosphines or as bistrialkyl phosphine complexes, can markedly improve potency against T. vaginalis and selectivity over human cells compared to that of the existing antirheumatic gold(I) drugs. All gold(I) complexes inhibited the two most abundant isoforms of the presumed target enzyme, thioredoxin reductase, but a subset of compounds were markedly more active against live T. vaginalis than the enzyme, suggesting that alternative targets exist. Furthermore, all tested gold(I) complexes acted independently of Mz and were able to overcome Mz resistance, making them candidates for the treatment of Mz-refractory trichomoniasis.

RhI Ar/AuI Ar' Transmetalation: A Case of Group Exchange Pivoting on the Formation of M-M' Bonds through Oxidative Insertion

By combining kinetic experiments, theoretical calculations, and microkinetic modeling, we show that Pf/Rf (C₆ F₅ /C₆ Cl₂ F₃ ) exchange between [AuPf(AsPh₃ )] and trans-[RhRf(CO)(AsPh₃ )₂ ] does not occur by typical concerted Pf/Rf transmetalation via electron-deficient double bridges. Instead, it involves asymmetric oxidative insertion of the Rh^I complex into the (Ph₃ As)Au-Pf bond to produce a [(Ph₃ As)Au-RhPfRf(CO)(AsPh₃ )₂ ] intermediate, followed by isomerization and reductive elimination of [AuRf(AsPh₃ )]. Interesting differences were found between the LAu-Ar asymmetric oxidative insertion and the classical oxidative addition process of H₂ to Vaska complexes.

Comparing Protonolysis and Transmetalation Reactions: Microcalorimetric Studies of C-AuI Bonds in [AuRL] Complexes

The protonolysis of C-Au bonds in [AuRL] organometallic complexes has been studied by calorimetry for 12 R groups. The experimental data have been combined with density functional theory calculations to obtain bond dissociation energy (BDE) values. The C-Au BDE values show a good correlation with the corresponding isolobal C-H BDE values. The heat released in the protonolysis of [AuRL] has also been measured for R = Ph and L = P(OPh)₃, PPh₃, PMe₃, PCy₃, and IPr, and these values strongly depend on the trans influence of L because of the mutual destabilization of the L-Au and Au-C bonds. The enthalpies of the transmetalation reaction [AuR(PPh₃)] + SnIBu₃ → [AuI(PPh₃)] + SnRBu₃ for seven R groups have been measured and compared with those of the corresponding [AuR(PPh₃)] protonolysis.

Novel organotin(iv) complexes derived from 4-fluorophenyl-selenoacetic acid: synthesis, characterization and in vitro cytostatic activity evaluation

A cluster of novel organotin(iv) complexes were designed, synthesized, and characterized by elemental analysis, FT-IR, and NMR (¹H, ¹³C, and ¹¹⁹Sn) spectroscopy as well as single-crystal X-ray diffraction.

Gold-catalyzed bis(stannylation) of propiolates

Bis(stannylation) of propiolates with hexabutylditin is achieved under mild conditions using a cationic gold(i) catalyst.