Efficient Direct Nitrosylation of α-Diimine Rhenium Tricarbonyl Complexes to Structurally Nearly Identical Higher Charge Congeners Activable towards Photo-CO Release.

Sara Nasiri Sovari,Isabelle Kolly,Youri Cortat,Aurelien Crochet,Kevin Schindler,Shing-Chi Liu,Fabio Zobi,Aleksandar Pavic

doi:10.3390/molecules26175302

Sara Nasiri Sovari, Isabelle Kolly + Show 6 more

Open Access

https://doi.org/10.3390/molecules26175302

Copy DOI

Abstract

The reaction of rhenium α-diimine (N-N) tricarbonyl complexes with nitrosonium tetrafluoroborate yields the corresponding dicarbonyl-nitrosyl [Re(CO)2(NO)(N-N)X]+ species (where X = halide). The complexes, accessible in a single step in good yield, are structurally nearly identical higher charge congeners of the tricarbonyl molecules. Substitution chemistry aimed at the realization of equivalent dicationic species (intended for applications as potential antimicrobial agents), revealed that the reactivity of metal ion in [Re(CO)2(NO)(N-N)X]+ is that of a hard Re acid, probably due to the stronger π-acceptor properties of NO+ as compared to those of CO. The metal ion thus shows great affinity for π-basic ligands, which are consequently difficult to replace by, e.g., σ-donor or weak π-acids like pyridine. Attempts of direct nitrosylation of α-diimine fac-[Re(CO)3]+ complexes bearing π-basic OR-type ligands gave the [Re(CO)2(NO)(N-N)(BF4)][BF4] salt as the only product in good yield, featuring a stable Re-FBF3 bond. The solid state crystal structure of nearly all molecules presented could be elucidated. A fundamental consequence of the chemistry of [Re(CO)2(NO)(N-N)X]+ complexes, it that the same can be photo-activated towards CO release and represent an entirely new class of photoCORMs.

Highlights

The growing trend of antimicrobial resistance (AMR) poses a serious threat to the public’s health, making it more and more difficult to prevent and treat related diseases.Thousands of deaths have been attributed to AMR infections according to WHO findings published in 2018 [1], with an estimated death toll of millions of cases per year by 2050 if the appropriate measures are not taken [2]
While similar complexes are reported as rhenium(I) dicarbonyl-nitrosyl species [24,25,26,27,28], the substitution chemistry of metal ion in fac-[Re(CO)2 (NO)(N-N)X]+ is that of a hard Re acid, probably due to the stronger πacceptor properties of NMR of [Re(CO)2 (NO)+ as compared to those of chemically modifying the fac-[ReI (CO)
We showed that fac[ReI (CO)3 (N-N)Br] complexes react efficiently with NOBF4 to yield the corresponding dicarbonyl-mononitrosyl species

Summary

Introduction

The growing trend of antimicrobial resistance (AMR) poses a serious threat to the public’s health, making it more and more difficult to prevent and treat related diseases.Thousands of deaths have been attributed to AMR infections according to WHO findings published in 2018 [1], with an estimated death toll of millions of cases per year by 2050 if the appropriate measures are not taken [2]. With the increasing difficulty of major pharmaceutical companies to meet the demand of new antibiotics discovery and production, universities are contributing to the finding of new classes of active compounds. Pathogens are likely to adapt rapidly and become resistant to new drugs if conventional medicinal chemistry approaches remain based exclusively on organic molecules, in light of the fact that the majority of drugs in clinical development are modified versions of already-approved antibiotics [3]. There is an increasing awareness in academia of the potential of metal complexes to act as the new class of molecules for the purpose. The unique chemistry and larger variety of 3D geometries of metal compounds can address targets and modes of action unavailable to organic molecules.

Methods

Results

Conclusion