Migratory insertion (MI) is one of the most important processes underpinning the transition metal-catalysed formation of C–C and C–X bonds. In this work, a comprehensive model of MI is presented,...

Insights into the factors controlling the site selectivity of transition metal-catalyzed C−H bond functionalization reactions are vital to their successful implementation in the synthesis of complex target molecules. The introduction of fluorine atoms into substrates has the potential to deliver this selectivity. In this study, we employ spectroscopic and computational methods to demonstrate how the "ortho-fluorine effect" influences the kinetic and thermodynamic control of C−H bond activation in manganese(I)mediated reactions. The C−H bond activation of fluorinated N,Ndimethylbenzylamines and fluorinated 2-phenylpyridines by benzyl manganese(I) pentacarbonyl BnMn(CO) 5 leads to the formation of cyclomanganated tetracarbonyl complexes (2a−b and 4a− e), which all exhibit C−H bond activation ortho-to-fluorine.Corroboration of the experimental findings with density functional theory methods confirms that a kinetically controlled irreversible σ-complex-assisted metathesis mechanism is operative in these reactions. The addition of benzoic acid results in a mechanistic switch, so that cyclomanganation proceeds through a reversible AMLA-6 mechanism (kinetically and thermodynamically controlled). These stoichiometric findings are critical to catalysis, particularly subsequent insertion of a suitable acceptor substrate into the C−Mn bond of the regioisomeric cyclomanganated tetracarbonyl complex intermediates. The employment of time-resolved infrared spectroscopic analysis allowed for correlation of the rates of terminal acetylene insertion into the C−Mn bond with the relative thermodynamic stability of the regioisomeric complexes. Thus, more stable manganacycles, imparted by an ortho-fluorine substituent, exhibit a slower rate of terminal acetylene insertion, whereas a para-fluorine atom accelerates this step. A critical factor in governing C−H bond site selectivity under catalytic conditions is the generation of the regioisomeric cyclomanganated intermediates, rather than their subsequent reactivity toward alkyne insertion.

Photolysis of trypto-CORM results in ultra-fast CO-dissociation and formation of a 16-e triplet followed by solvation.

Photolysis of [Mn(C^N)(CO)4] (C^N = bis-(4-methoxyphenyl)methanimine) in heptane solution results in ultra-fast CO dissociation and ultimate formation of a rare Mn-containing dinitrogen complex fac-[Mn(C^N)(CO)3(N2)].

Manganese-mediated borylation of aryl/heteroaryl diazoniums alts emerges as ag eneral and versatile synthetic methodology for the synthesis of the corresponding boronate esters. The reactionp roved an ideal testing ground for delineating the Mn species responsible for the photochemical reactionp rocesses, that is, involving either Mn radical or Mn cationic species, which is dependent on the presence of as uitably strong oxidant. Our findingsa re important for ap lethora of processes employing Mn-containing carbonyl speciesa si nitiators and/or catalysts, which have considerable potential in synthetic applications. Scheme1.Light mediated borylation of aryl diazoniums.