The preparation of the complexes TpMo(NO)(DMAP)(η-PhCF) (5) and TpMo(NO)(DMAP)(η-benzene) (3) is described. The CF group is found to stabilize the metal-arene bond strength in 5 by roughly 3 kcal/mol compared to that in 3, allowing the large-scale synthesis and isolation of the trifluorotoluene analogue (5, 37 g, 70%). When a benzene solution of 5 is allowed to stand, clean conversion to the benzene analogue 3 occurs, and this complex may be precipitated from solution upon the addition of pentane and isolated. The trifluorotoluene complex is shown to be a synthetic precursor to functionalized cyclohexadienes: In solution, it selectively protonates at the ortho position, and the resulting η-arenium species undergoes reactions with nucleophiles at the adjacent meta carbon. Thus, reactions of 5, triflic acid, and either N-methylpyrrole or 1-methoxy-2-methyl-1-(trimethylsilyloxy)-1-propene result in 5-substituted-1,3-cyclohexadienes after removal of the metal.

A wide range of η 2 -coordinated pyridine complexes are accessible to molybdenum, avoiding κN coordination • Coordinated pyridines can be functionalized and subsequently decomplexed to produce dihydropyridines • Dihydropyridines can be elaborated into novel isoquinuclidines • Enantioselective synthesis is possible, with demonstrated er > 94:6 • Conditions are being sought to functionalize remaining uncoordinated double bond of dihydropyridine complexes to yield tetrahydropyridines

Key steps in the functionalization of an unactivated arene often involve its dihaptocoordination by a transition metal followed by insertion into the C-H bond. However, rarely are the η 2 -arene and aryl hydride species in measurable equilibrium. In this study, the benzene/phenyl hydride equilibrium is explored for the {WTp(NO)(PBu 3 )} (Bu = n-butyl; Tp = trispyrazoylborate) system as a function of temperature, solvent, ancillary ligand, and arene substituent. Both face-flip and ring-walk isomerizations are identified through spin-saturation exchange measurements, which

Rationale: Infectious disease remains the main cause of morbidity and mortality throughout the world.Of growing concern is the rising incidence of multidrug-resistant bacteria, derived from various selection pressures. Many of these bacterial infections are hospital-acquired and have prompted the Center for Disease Control and Prevention in 2019 to reclassify several pathogens as urgent threats, its most perilous assignment. Consequently, there is an urgent need to improve the clinical management of bacterial infection, via new methods to specifically identify bacteria and monitor antibiotic efficacy in vivo. In this report, we developed a novel radiopharmaceutical, 18 Ffluoromannitol ( 18 F-FMtl), which we show is specifically accumulated in both gram-positive and gram-negative bacteria but not in mammalian cells in vitro or in vivo.Methods: Clinical isolates of bacteria were serially obtained from wounds of combat service members for all in vitro and in vivo studies. The quantification of bacterial infection in vivo was performed using Positron Emission Tomography (PET)/CT imaging, and infected tissue was excised to confirm radioactivity counts ex vivo. These same tissues were used to confirm the presence of bacteria by extracting and correlating radioactive counts with colony forming units (CFU) of bacteria.Results: 18 F-FMtl was able to differentiate sterile inflammation from S. aureus and E. coli infections in vivo in a murine myositis model using PET imaging. Our study was extended to a laceration wound model infected with A. baumannii, an important pathogen in the nosocomial and battlefield setting.18 F-FMtl PET could rapidly and specifically detect infections caused by A. baumannii and several other important ESKAPE pathogens. Importantly, 18 F-FMtl PET was able to monitor therapeutic efficacy of vancomycin against S. aureus in vivo.Principal Conclusions: The ease of production of 18 F-FMtl is anticipated to facilitate wide radiopharmaceutical dissemination. Furthermore, the broad sensitivity of 18 F-FMtl for bacterial infection in vivo suggests that it is an ideal imaging agent for clinical translation to detect and monitor infections and warrants further studies in the clinical setting.

The exceptionally π-basic metal fragments {MoTp-(NO)(DMAP)} and {WTp(NO)(PMe 3 )} (Tp = tris(pyrazolyl)borate; DMAP = 4-(N,N-dimethylamino)pyridine) form thermally stable η 2 -coordinated complexes with a variety of electron-deficient arenes. The tolerance of substituted arenes with fluorine-containing electron withdrawing groups (EWG; −F, −CF 3 , −SF 5 ) is examined for both the molybdenum and tungsten systems. When the EWG contains a π bond (nitriles, aldehydes, ketones, ester), η 2 coordination occurs predominantly on the nonaromatic functional group. However, complexation of the tungsten complex with trimethyl orthobenzoate (PhC(OMe) 3 ) followed by hydrolysis allows access to an η 2 -coordinated arene with an ester substituent. In general, the tungsten system tolerates sulfur-based withdrawing groups well (e.g., PhSO 2 Ph, MeSO 2 Ph), and the integration of multiple electron-withdrawing groups on a benzene ring further enhances the π-back-bonding interaction between the metal and aromatic ligand. While the molybdenum system did not form stable η 2 -arene complexes with the sulfones or ortho esters, it was capable of forming rare examples of stable η 2 -coordinated arene complexes with a range of fluorinated benzenes (e.g., fluorobenzene, difluorobenzenes). In contrast to what has been observed for the tungsten system, these complexes formed without interference of C−H or C−F insertion.