Maxim G. Chegerev

New paramagnetic tin(IV) complexes based on o-iminoquinone ligands: Synthesis and thermal transformation

A series of new paramagnetic tin(IV) complexes based on sterically hindered o-iminobenzoquinones (R)ImQ differed in fragments (R) in the N-aryl fragment is synthesized. The thermal transformation of the tin(IV) complex, (iso-Pr)ImSQSn(tert-Bu)2Cl ((iso-Pr)ImSQ is the radical anion of 4,6-di-tert-butyl-N-(2,6-di-iso-propylphenyl)-o-iminobenzoquinone), is studied. The thermal transformation of the paramagnetic complex in nonane results in the formation of a new tin(II) bis(aminophenolate) derivative. The synthesized complexes and the thermolysis product are characterized by EPR, IR, and 1H, 13C, and 119Sn NMR spectroscopy and elemental analysis. The structures of the (tert-Bu)ImSQSn(tert-Bu)2Cl complex and the thermal decomposition product, {(iso-Pr)AmPh}2Sn ((iso-Pr)AmPh is 2-(2,6-di-iso-propylphenyl)amino-4,6-di-tert-butylphenolate), are determined by X-ray diffraction analysis.

Chemistry of Complexes of Group 14 Elements Based on Redox-Active Ligands of the o-Iminoquinone Type

Specific features of the synthesis and structures of the complexes of Group 14 elements (Si, Ge, Sn, Pb) with o-iminoquinone ligands are discussed. The chemical reactions of the above indicated compounds accompanied by the transformation of the redox-active ligand in the coordination sphere of the complex- forming agent are considered.

Compounds of potassium and tin(II) with diiminopyridine ligands: EPR spectroscopy and theoretical study

Potassium and tin(II) derivatives of the paramagnetic forms of the redox-active 2,6-bis(2,6-diisopropylphenyliminomethyl)pyridine were synthesized and studied by means of EPR spectroscopy. It was shown that the reaction with metallic potassium involves the three-electron step reduction of the organic ligand to form a radical anion, dianion, and trianion radical, respectively. The reactions of the tin(II) diiminopyridine derivatives with metallic magnesium give complexes comprising the radical anion form of the ligand and a low-valence metal center. The geometries of the paramagnetic products and their spin density distributions were explored in terms of the density functional theory.

Polymerization of methyl methacrylate in the presence of o-iminoquinones: Reversible and irreversible inhibition

New regulators of radical polymerization of methyl methacrylate based on N-(aryl)-o-iminoquinones of various structures are proposed. It is shown that samples of polymethylmethacrylate with the participation of N-(aryl)-o-iminobenzoquinones could be used as macroinitiators of polymerization. Optimal conditions to synthesize polymers in the presence of o-iminobenzoquinones are determined, which make it possible to obtain polymethylmethacrylate with a polydispersity coefficient of no more than 1.5 on deep conversions during bulk polymerization.

N-aryl-o-iminobenzoquinones as novel regulators of radical polymerization

The effect of a number of quinoid compounds on methyl methacrylate polymerization initiated by azo-bis(isobutyronitrile) has been studied. It has been revealed that N-aryl-o-iminobenzoquinones, in contrast to o-benzoquinones, can provide radical polymerization of methyl methacrylate in controllable mode. The efficiency of the compounds as chain growth regulators has been found to depend on their composition and reaction conditions. It has been established that 4,6-di-tert-butyl-N-(2,6-diethylphenyl)-o-iminobenzoquinone and 4,6-di-tert-butyl-N-(2,6-diisopropylphenyl)-o-iminobenzoquinone under radical initiation conditions provide the synthesis of poly(methyl methacrylate) with wide-range molecular weight, retaining polydispersity indices about ~1.4–1.8 up to deep conversions.