New enamine ligands derived from ethyl 2-ethoxymethylidene-3-oxo-3-polyfluoroalkylpropionates and o-phenylenediamine

Abstract

Diethyl 2,2´ [1,2 phenylenebis(aminomethylidene)]bis(3 oxo 3 polyfluoroalkylpropion ates) were synthesized by the condensation of a double excess of ethyl 2 ethoxymethylidene 3 oxo 3 polyfluoroalkylpropionates with o phenylenediamine. The use of equimolar ratios of the starting reactants affords ethyl 2 [(2 aminophenyl)aminomethylidene] 3 oxo 3 polyfluoroalkylpropionates from which nonsymmetric biscondensation products were syn thesized by the reaction with related reactants containing different polyfluoroalkyl substituent. The copper(II), nickel(II), and cobalt(II) complexes were obtained on the basis of new ligands.Interest in synthesis of metal complexes based on azomethine compounds is caused by their catalytic activity in polymerization reactions 1-3 and magnetic 4-7 and luminescence 8,9 properties. Non fluorinated 2 ethoxy methylidene 1,3 dicarbonyl compounds in reactions with 1,2 diamines form biscondensation products at the ethoxymethylidene moiety 10-12 and related metal com plexes. 13-16 It is possible to obtain monocondensation products 17-19 from which symmetric and asymmetric ligands 20 were synthesized, including the macrocyclic ligands 15,17-20 used in the synthesis of the metallocomplex compounds. 17-20 Schiff bases obtained by transformations of 2 ethoxymethylidene 3 oxo 3 fluoroalkylpropionates with different diamines can also serve as organic mol ecules forming the ligand shell. It is known 21 that the introduction of the fluorine atom into organic molecules changes their physicochemical properties, reactivity, bio logical activity and other characteristics caused by the presence of electronegative fluorine atoms and important in practical and theoretical aspects. However, published data on the participation of polyfluorinated analogs in similar polycondensation reactions are lacking.In the present work, we studied the reactions of ethyl 2 ethoxymethylidene 3 oxo 3 polyfluoroalkylpropion ates 1 with o phenylenediamine with the purpose to syn thesize new ligands and analyzed a possibility of the prepa ration of related metallocomplex compounds with a series of transition metals.It was found that the reaction of compounds 1a-c with 1 equiv. of o phenylenediamine in diethyl ether at room temperature afforded the monoadducts, viz., ethyl 2 [(2 aminophenyl)aminomethylidene] 3 fluoroalkyl 3 oxopropionates 2a-с, as a result of the nucleophilic attack of the amino group at the ethoxymethylidene moiety (Scheme 1). The use of a double excess of esters 1a-c results in the formation of symmetric products 3a-c due to the condensation of two molecules of ester 1a-c with one diamine molecule.Monosubstitution products 2а-c contain free NH 2 groups, which makes it possible to carry out their further transformations. The condensation of compounds 2а,с with the corresponding substrates 1a,b (see Scheme 1)

Influence of CF3 Substituents on the Spin Crossover Behavior of Iron(II) Coordination Polymers with Schiff Base‐like Ligands

“…Herein we present five iron(II) coordination polymers with different axial ligands based on Saloutin's previously mentioned Schiff base‐like ligand system . One crystal structure of a coordination polymer was obtained and PXRD patterns of all compounds were investigated.…”

“…Indeed, in previous work by Saloutin et al on nickel(II) complexes bearing CF 3 substituents no short-range interactions were reported. [23] In addition, the electron withdrawing effect of the CF 3 substituents is expected to alter the ligand field strength of the iron(II) metal center and thus the SCO behavior on the molecular level.…”

“…Herein we present five iron(II) coordination polymers with different axial ligands based on Saloutin's previously mentioned Schiff base-like ligand system. [23] One crystal structure of a coordination polymer was obtained and PXRD patterns of all compounds were investigated. Moreover, the magnetic behavior of all coordination polymers was investigated in detail using magnetic susceptibility measurements and Mössbauer spectroscopy.…”

Asymmetric azomethine ligands based on 2-[(2-aminophenyl)aminomethylidene]-3-oxo-3-polyfluoroalkylpropionates and aldehydes

“…In this respect, metal complexes containing Schiff bases as the ligand shell deserve special attention because certain compounds belonging to this class have catalytic, 1-4 anomalous magnetic, 5-8 and luminescence 9 properties. Previously, 10 we have synthesized ethyl 2 [(2 amino phenyl)aminomethylidene] 3 oxo 3 polyfluoroalkylpro pionates 1a-c by the condensation of ethyl 2 ethoxy methylidene 3 oxo 3 polyfluoroalkylpropionates with о phenylenediamine. Compounds 1a-c are promising substrates for the synthesis of new ligands.…”