Mono- and bimetallic pentacoordinate silicon complexes of a chelating bis(catecholimine) ligand

Abstract

A xanthenediamine-based bis(iminocatecholate) occupies trans sites in square pyramidal silicon adducts and binds univalent ions in a lower N2O3 pocket.

Synthesis, Structure and Electrochemical Properties of Acetamide- and Caprolactam-Containing Silicon Catecholates

“…The oxidation processes for the latter compounds were the irreversible and homolytic cleavage of the Si−R bond. In macrocyclic compound [(XbicH 2 )SiPh][HCl 2 ] [12] the value of irreversible oxidation potential was almost the same as in the abovementioned bis(catecholato)silicon complex with R = Ph (+0.81, Fc + /Fc, CH 2 Cl 2 ). In general, the coordination of the metal atoms to oxygen ones of catecholate ligands leads to a significant decrease of oxidation potentials.…”

“…To date, the mechanism of electrochemical oxidation/reduction of hypervalent silicon compounds is still not revealed completely. In literature, there are few examples of electrochemical oxidation/reduction of compounds of silicon with derivatives of pyrocatechol [11][12][13]. As it follows from quantum chemical calculations, there should be several high lying redox-active orbitals localized on catecholate ligands [12].…”

“…In literature, there are few examples of electrochemical oxidation/reduction of compounds of silicon with derivatives of pyrocatechol [11][12][13]. As it follows from quantum chemical calculations, there should be several high lying redox-active orbitals localized on catecholate ligands [12]. The influence of organic substituents on the oxidation potential can be explained by π→σ* donation from respective orbitals of catecholate ligands to those of a substituent.…”

“…It was demonstrated that pentacoordinated silicon atoms connected with an aryl or alkyl group beside two catecholate anions undergo irreversible electrochemical oxidation and can be used as a source of allyl radicals [11]. The binding of silicon benzoquinones with catecholate anions increased their stability towards electrochemical oxidation [12] that allowed a macrocyclic ligand with pentacoordinated silicon able to bind with various metal cations to be obtained. Silicon complexes containing both catecholate and 1,10-dipyridyl undergo reversible redox processes [13].…”

Imine-Based Catechols and o-Benzoquinones: Synthesis, Structure, and Features of Redox Behavior

“…Catechol derivatives without tert -butyl groups, especially catecholamides and catecholaldimines, are well known as ligands for supramolecules (helicate structures and molecular tetrahedrons) 9 − 16 and bimetallic catalysts for the Mannich and Henry reactions; 17 − 22 however, these ligands do not have stable oxidized forms. 23 Salicylaldehyde and its derivatives attract attention due to the accumulated data on their anti-infection properties. 24 − 26 The structures of hydroxylated salicylaldehydes contain pharmacophores of the natural compound gossypol, 27 − 30 which is known for its high antiviral activity.…”