Facile rearrangement and electron transfer of 19-electron radicals from the reduction of the bischelated manganese carbonyl cation Mn(CO)2[PPh2(CH2)2PPh2]2+

Abstract

The cathodic reduction of the bischelated manganese carbonyl cation iran.r-Mn(CO)2(?)2-DPPE)2+ (I+, where DPPE = PPh2-(CH2)2PPh2) produces the metastable anion Mn(CO)2(jt2-DPPE)(n1-DPPE)" ( ) via an overall 2e process at a Pt electrode in either tetrahydrofuran or acetonitrile solution. The unusual observation of a cathodic curve crossing and two isopotential points in the cyclic voltammogram of I+ can be traced to an electron transfer with II" to afford a pair of neutral radicals, i.e., the 19e I' and the 17e II'. The former (which is also generated during the initial step in the reduction of I+) is a metastable species and spontaneously extrudes an end of one DPPE ligand to afford the second radical IP with the rate constant kT == 4 X 106 s"1. The structures of the anionic and radical intermediates II", IP, and P are discussed in the context of their transient electrochemical behavior as well as their 31P NMR and ESR spectra. The rather slow rate of electron transfer between I+ and II" is ascribed to steric effects in carbonylmanganese ions encumbered with a pair of DPPE ligands.

Ligand Design for Electrochemically Controlling Stoichiometric and Catalytic Reactivity of Transition Metals

“…(b)]. [14] This can be an effective way of electrochemically opening and closing a coordination site at a metal center. When this approach is applied to metal ± arene complexes, interesting changes in arene hapticity are observed, [15] which often lead to reactivity inaccessible to the complexes before reduction.…”

“…linkage isomerism), [15,17] redox-induced ligand exchange reactions, [18] geometrical isomerism, [19] and redox-induced binding or expulsion of a ligand. [14,20] This approach has even been used in elaborate gas-separation schemes involving a Cu I /Cu II redox couple. [21] As opposed to ligand-based approaches to changing the reactivity of transition metals, these redox reactions based at the central metal drastically alter both the electronic (oxidation state) and steric environments of the bound metal and, therefore, the type of chemistry that the metal center might mediate.…”

Hirshfeld surface and theoretical studies of 2,2,2-trichloro-N,N-bis(2-(2,2,2-trichloroacetamido)phenyl)acetamide compound

“…The redox active compounds containing amide donors can be modified according to specific needs and most of them have catalytic activity [1][2][3][4][5][6][7][8][9]. So, in recent years, most of the researchers focused on these types of compounds.…”

Entwicklung von Liganden zur elektrochemischen Kontrolle der stöchiometrischen und katalytischen Reaktivität von Übergangsmetallen

“…(b)]. [14] Dies kann eine effektive Methode sein, um eine Koordinationsstelle an einem Metallzentrum freizulegen oder zu besetzen. Bei Aren-Metallkomplexen führt diese Methode zu interessanten Veränderungen in der Aren-Hapticität, [15] die oft zu Reaktivitäten führen, die für die Komplexe vor der Reduktion unerreichbar waren.…”

“…B. Verknüpfungsisomerie), [15,17] redoxinduzierte Liganden-Austauschreaktionen, [18] geometrische Isomerie [19] und die redoxinduzierte Bindung oder Abspaltung eines Liganden. [14,20] Diese Methode ist sogar bei hochentwickelten Gastrennsystemen mit einem Cu I /Cu II -Redoxpaar angewendet worden. [21] Im Unterschied zu den am Liganden ansetzenden Methoden zur Veränderung der Übergangsmetallreaktivität bewirken die Redoxreaktionen am zentralen Metall drastische Veränderungen sowohl in der elektronischen (Oxidationszustand) als auch in der sterischen Umgebung des gebundenen Metallzentrums und damit auch in der Art der Chemie, die dieses Metallzentrum vermitteln könnte.…”