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Cationic Charges Leading to an Inverse Free‐Energy Relationship for N−N Bond Formation by Mn VI Nitrides
Author(s) -
Chantarojsiri Teera,
Reath Alexander H.,
Yang Jenny Y.
Publication year - 2018
Publication title -
angewandte chemie international edition
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 5.831
H-Index - 550
eISSN - 1521-3773
pISSN - 1433-7851
DOI - 10.1002/anie.201805832
Subject(s) - chemistry , schiff base , cationic polymerization , oxidizing agent , ligand (biochemistry) , alkali metal , crystallography , metal , ion , inorganic chemistry , stereochemistry , polymer chemistry , receptor , biochemistry , organic chemistry
Mn V N Schiff‐base complexes incorporating a Na + ( 1Na ), K + ( 1K ), Ba 2+ ( 1Ba ), or Sr 2+ ( 1Sr ) ion in the ligand framework are reported. The Mn VI/V reduction potentials for 1Na , 1K , 1Ba , and 1Sr are 0.591, 0.616, 0.805, and 0.880 V vs. Fe(C 5 H 5 ) 2 +/0 , respectively, exhibiting significant positive shifts compared to a MnN Schiff‐base complex in the same primary coordination environment but with no associated alkali or alkaline earth metal ion ( A , E 1/2 =0.427 V vs. Fe(C 5 H 5 ) 2 +/0 ). One‐electron oxidation of the Mn V N complexes results in bimolecular coupling to form N 2 with rates (k 2 ) at 20 °C of 2166, 684, 857, and 99.7, an 87 m −1 s −1 for A , 1Na , 1K , 1Ba , and 1Sr respectively, following an inverse linear free energy relationship. Thus, increasing charge through proximal cations results in Mn VI N complexes that are both more oxidizing and more stable to bimolecular coupling, a trend diametrically opposed to when complexes were modified by ligand substituents through inductive effects.