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Reactivity of (Dicarboxamide)M II –OH (M = Cu, Ni) Complexes – Reaction with Acetonitrile to Yield M II –Cyanomethides
Author(s) -
Tehranchi Jacqui,
Donoghue Patrick J.,
Cramer Christopher J.,
Tolman William B.
Publication year - 2013
Publication title -
european journal of inorganic chemistry
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.667
H-Index - 136
eISSN - 1099-0682
pISSN - 1434-1948
DOI - 10.1002/ejic.201300328
Subject(s) - chemistry , reactivity (psychology) , deprotonation , acetonitrile , nitrile , ligand (biochemistry) , medicinal chemistry , isopropyl , pyridine , yield (engineering) , hydroxide , metal , stereochemistry , inorganic chemistry , organic chemistry , medicine , ion , biochemistry , materials science , alternative medicine , receptor , pathology , metallurgy
The complexes (Bu 4 N)(L Me M II –OH) (L Me = 2,6‐dimethylphenyl‐substituted pyridine(dicarboxamide); M = Cu or Ni) react with CH 3 CN to yield (Bu 4 N)(L Me M–CH 2 CN) cyanomethide complexes, which were fully characterized, including by X‐ray crystallography. These conversions contrast with the usual reactions of metal hydroxide complexes with nitriles, which typically involve attack at the nitrile carbon atom and formation of amides or carboxylic acids. Kinetic studies (M = Cu) revealed a first‐order dependence on the complex and a kinetic isotope effect [ k (CH 3 CN)/ k (CD 3 CN)] of 4. Various mechanisms involving either intra‐ or intermolecular deprotonation steps are proposed. In addition, (Bu 4 N)(L Me Cu–OH) was oxidized by ferrocenium hexafluorophospate (FcPF 6 ) to a proposed Cu III complex L Me CuOH at low temperature, and comparisons of its stability and reactivity with dihydroanthracene were drawn to its previously described congener with isopropyl substituents on the phenyl rings of the supporting ligand. The cyanomethide complex (Bu 4 N)(L Me Cu(CH 2 CN)) was also reversibly oxidized both electrochemically ( E 1/2 = –0.345 V vs. Fc/Fc + ) and chemically (FcPF 6 , –25 °C). The product was formulated as L Me Cu III (CH 2 CN), a new Cu III –alkyl complex relevant to such species proposed during copper‐catalyzed organic reactions.