Metal‐Chelating N,N′‐Bis(4‐dimethylaminophenyl)acetamidinyl Radical: A New Chromophore for the Near‐Infrared Region

Abstract

A new non-innocent ligand redox system, N,N'-bis(4-dimethylaminophenyl) substituted acetamidinato/acetamidinyl, has been designed and described by example of structurally and spectroscopically characterized ruthenium complexes. The hitherto unreported ligand is responsible for rather intense and narrow absorptions in the near-infrared region of the one- and two-electron oxidized forms. The spectroscopic, computational, and first structural characterization of an amidinyl radical complex adds to the list of established N-based radical ligands.

Structural and Oxidation State Alternatives in Platinum and Palladium Complexes of a Redox‐Active Amidinato Ligand

“…The cationic form is thus assigned an oxidation state formulation [(Pd 2.5 ) 2 (L − ) 4 ] + , in agreement with earlier assignments for Pd 2 5+ species [15] . This result proves that the dipalladium(II) unit Pd 2 4 + is giving up an electron easier than the oxidizable [8] ligands L − . These appear to be oxidized only in further steps which include more than one electron according to the cyclic voltammetry experiment (Figure 5).…”

“…In addition to the unexpected constitutional and structural differences of the two M II compounds 1 and 2 , the oxidation behavior showed distinct alternatives. In agreement with the established [8] facile oxidation of the ligand L − to the radical L . the compound 1 exhibits stepwise ligand‐based electron removal, avoiding an oxidation of the metal to the uncommon Pt III state or formation of a diplatinum compound [22] .…”

“…The DFT calculation results reproduce the experimental geometry (Table S2). Therefore the system is best described as [Pt II (L − ) 2 ] and not as [Pt 0 (L ) 2 ] which might have been anticipated considering the facile oxidation of L − [8] …”

“…A new N ‐coordinating type of radical ligand has been presented by us recently [8, 9] in the form of amidinyl radicals [RNC(R’)NR] . =L , R =4‐dimethylaminophenyl, R’=CH 3 [8] . With ruthenium complex fragments there exists an ambiguity in oxidation state formulation, Ru III (L − ) vs. Ru II (L ), for certain oxidized forms, depending on the co‐ligands [9] .…”

Synthesis and pharmacological evaluation of donepezil-based agents as new cholinesterase/monoamine oxidase inhibitors for the potential application against Alzheimer’s disease

“…Although a part of donepezil-like compounds have been known, their biological activities such as the inhibition of ChEs and MAOs have not been determined [41][42][43] . Meanwhile, the amide of 2-picolinamide moiety also has the ability to chelate metal ions 44,45 . In this study, we described the design, synthesis, and evaluation of series of donepezil-like compounds which were found to show potential abilities, including the inhibition of ChEs, inhibition of MAOs, metal chelation and penetration of the blood-brain barrier (BBB).…”