Auswahl der wissenschaftlichen Literatur zum Thema „[Cp*Ir(bpy-OMe)H]+“

In methanolic solutions of A₄[{LM′}₂M₆O₁₉] ({LM′} = {Cp*Rh}²⁺, {Cp*Ir}²⁺, {(C₆H₆)Ru}²⁺; M = Nb, Ta; A = Na, K) formation of methoxo complexes [{LM′}₂M₆O_19−n(OMe)n] (n = 1–3) and coordination of CH₃OH to A⁺ take place.

The series of ethylene glycol di-para-X-benzoates, where X = Me, OMe, CN, and NO2, has been studied by infrared spectroscopy and solid state CP/MAS 13C nuclear magnetic resonance. The crystal structures were established for X = Me and OMe. Bond distances, bond angles, and torsion angles were compared to those of related molecules (X = H, Ph, Cl). It was found that the conformation of the CO—O—CH2—CH2—O—CO sequence is either trans-trans-trans or trans-gauche-trans. (trans = t, gauche = g). The CH2—CH2 bond distance ranging from 1.471(2) to 1.499(3) Å is always very short. The O—CH2—CH2 bond angle is around 105° for the ttt conformation and 107° for the tgt conformation. It was confirmed that the infrared frequencies for the CH2 bending, CH2 wagging, C–C stretching, and CH2 rocking modes are observed at 1470–1485, 1335–1340, 975–980, 845–855 cm−1 and at 1460, 1370–1375, 1040, 895–900 cm−1 for the ttt and tgt conformations respectively. The substitution effect on the nmr chemical shifts, both in solution and the solid state, can be rationalized in terms of induction and resonance contributions. On the basis of the ir and nmr spectra, it is proposed that for both the p-NO2 and p-CN substituted molecules, for which no crystal structure has been established, the conformation of the methylenic sequence is trans-trans-trans.

Taking advantage of the unique properties of two-component flavo-monooxygenases and the ability of [Cp*Ir(bpy-OMe)H]+ to transfer hydrides to reduce flavins, we extended the scope of this pH- and oxygen-robust iridium(III)-complex...

Le terme monooxygénases flavoprotéiques (flavoprotein monooxygenases FPMO) recouvre aussi bien des flavoenzymes formées d’une seule composante que de deux. L'indépendance fonctionnelle de la partie oxygénase de la 2,5-dicétocamphane 1,2-monooxygénase I (2,5-DKCMO), une Baeyer-Villiger monooxygénase de type II, FMN dépendante, de sa contrepartie réductase, ainsi que le mécanisme de transfert de la flavine par libre diffusion, ont été étudiés dans des réactions sans réductase mais où des analogues biomimétiques synthétiques de nicotinamide (NCB) ont été utilisés pour réduire le FMN. L'équilibre entre la réduction de la flavine et la (ré)oxydation enzymatique a été identifié comme le goulot d'étranglement du système. Dans le but de trouver des donneurs d'hydrure potentiellement rentables pour les réactions d'oxydoréduction enzymatique, des stratégies de réduction de la flavine, indépendantes des cofacteurs nicotinamide naturels et biomimétiques, ont été étudiées. La capacité d’un complexe d’iridium III à transférer des hydrures afin de réduire la flavine a été exploitée. [Cp*Ir(bpy-OMe)H]+ (Ir* (H+)), résistant au pH et à l'oxygène, a permis la réaction enzymatique de monooxygénases respectivement FMNH2 et FADH2 dépendantes, 2,5-DKCMO et la styrène monooxygénase de sphingopyxis fribergensis Kp.5.2 (SfStyA). L’utilisation du système Ir* (H+)/SfStyA a conduit à une augmentation de six fois de l’état de l’art en terme de turn over number (TON) d’un catalyseur métallique. Cependant des améliorations sont encore nécessaires pour confirmer cette approche comme un accès prometteur à une plate-forme technologique efficace et versatile, pour l’utilisation de flavoenzymes
The term flavoprotein monooxygenases (FPMO) covers two different types of flavoenzymes: single and two component oxygenases. Two component FPMOs consist of a reductase and an oxygenating enzyme. The functional independence of the oxygenase part of 2,5-diketocamphane 1,2-monooxygenase I (2,5 DKCMO), an FMN dependent type II Baeyer-Villiger monooxygenase, from the reductase counterpart, as well as the mechanism of flavin transfer by free diffusion, was investigated in a reductase-free reaction, using synthetic nicotinamide biomimetics (NCBs) for the reduction of FMN. The balance of flavin reduction and enzymatic (re)oxidation was identified as the bottleneck of the system. Aiming for potentially cost efficient hydride donors for enzymatic redox reactions, nicotinamide coenzyme and nicotinamide biomimetic independent flavin reduction strategies were investigated. The capability of the pH and oxygen robust iridium III complex [Cp*Ir(bpy-OMe)H]+ (Ir* (H+)) to transfer hydrides for flavin reduction for the enzymatic reaction of respectively FMNH2 and FADH2 dependent monooxygenases, 2,5 DKCMO and styrene monooxygenase from Sphingopyxis fribergensis Kp.5.2 (SfStyA) was exploited. The Ir* (H+)/SfStyA approach outperformed the state of the art system by six-fold in terms of turn over number of the metal catalyst. Nevertheless, the robustness of the system remains challenging, and improvements are required to establish the approach as an efficient and versatile platform technology for flavoenzymes