Using sterics to promote reactivity in fac-Re(CO)3 complexes of some ‘non-innocent’ NNN-pincer ligands

Abstract

Two new redox active ligands based on di(2-(3-organopyrazolyl)-p-tolyl)amine have been prepared in order to investigate potential effects of steric bulk on the structures, electronic properties, or reactivity of tricarbonylrhenium(I) complexes. Replacing the hydrogens at the 3-pyrazolyl positions with alkyl groups causes significant distortion to the ligand framework due to potential interactions between these groups when bound to a fac-Re(CO)(3) moiety. The distortions effectively increase the nucleophilic character of the central amino nitrogen and ligand-centered reactivity of the metal complexes.

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“…The 1 H NMR spectra were recorded for one of the ligands -bis-(benzimidazolyl) pyridine and for its copper complex in DMSO-d 6 as solvent.…”

“…The pincer complexes have been employed as catalysts in various bond activation reactions. [5][6][7]  They have also been evaluated as efficient anticancer agents through DNA binding studies. 8 In this project, bis benzimidazolyl ligands with pyridine and benzene as bridging moieties to give NNN and NCN ligands have been prepared.…”

The crystal structure of diaqua-(N-(2-hydroxy-5-nitrobenzyl)iminodiacetato-κ4-N,O,O′,O′′)chromium(III) based on synchrotron data, C11H13CrN2O9

“…There is a compelling interest in the synthesis and characterization of transition metal complexes with pincer ligands for the wide range of studies from catalysis to bioinorganic and materials chemistry [1][2][3]. R-H 3 XD′S [N-(2-hydroxy-5-R-benzyl)iminodiacetic acids with R = CH 3 , Cl, Br, OMe, and NO 2 etc], are versatile acidic pincer ligands, which have one chelating arms like a single arm crab.…”

Cobalt(ii) and copper(ii) supramolecular networks with a 1-iminoisoindoline asymmetric pincer

“…2 Different types of pincers 3 were synthesized and characterized including E,C,E type pincers with various E donors, including P, N and S atoms and C-ipso carbanions. 10 Another advantage of the pincer ligands is nowadays their asymmetric structure, hemilability and chirality which are the features required for asymmetric catalysis. [5][6][7][8] Usually, rigid and bulky analogues of E,C,E pincer ligands coordinate meridionally 9 and substitution of the C-ipso atom is associated with gaining non-innocent character by the ligand.…”