M. Nechaev - Academia.edu (original) (raw)
Papers by M. Nechaev
Polymer Science, Series B, 2020
The polymerization of commercial strained cycloalkene, 5-ethylidene-2-norbornene, in the presence... more The polymerization of commercial strained cycloalkene, 5-ethylidene-2-norbornene, in the presence of Pd-N-heterocyclic carbene complexes (two of which are synthesized for the first time) containing phosphine or pyridine ligands is studied. Upon activation with borate Na + [B(3,5-(CF 3) 2 C 6 H 3) 4)]-, the studied Pd complexes catalyze the polymerization of 5-ethylidene-2-norbornene according to the addition scheme. Polymerization proceeds selectively and involves only the endocyclic (norbornene) double bond of the monomer, while the exocyclic (ethylidene) double bond remains unaffected. Pd-N-heterocyclic carbene complexes with phosphine ligands are inactive in polymerization, while similar complexes with 3-chloropyridine ligands show a higher activity. Two new Pd complexes are synthesized.
Polymer Science, Series C, 2019
Using the commercial derivative of norbornene-5-ethylidene-2-norbornene-a series of three isomeri... more Using the commercial derivative of norbornene-5-ethylidene-2-norbornene-a series of three isomeric homopolymers with different structure of the backbone is synthesized, and the effect of the chain structure on the gas-transport behavior of polynorbornenes is studied. The gas-transport characteristics of the polymers are presented together with data on the conformation properties of molecules of addition and metathesis polynorbornenes. The effect of the structure of side substituents on the equilibrium rigidity of addition polynorbornenes is confirmed by the example of poly(5-ethylidene-2-norbornene) and poly(5vinyl-2-norbornene).
New Journal of Chemistry, 2019
Low energy barriers are found for inter-ring haptotropic rearrangements on large PAH ligands.
ChemInform, 2010
Heteroorganic Betaines. Part 4. Photolysis and Thermolysis of Betaines Containing the + P-C-Si-S ... more Heteroorganic Betaines. Part 4. Photolysis and Thermolysis of Betaines Containing the + P-C-Si-S − Structural Fragment.-Thermal and photolytic decomposition of betaines like (I) follows two main pathways: the Corey-Chaykovsky reaction pattern to give silathiirane intermediate (IX) or a retro-Wittig type reaction to generate silanethione intermediate (X). The former reaction is observed during photolysis of compound (I), and the silathiirane intermediate can be isolated as dimer (II) or trapped with acetone to give oxathiasilolane (XI). Under thermal reaction conditions both pathways are observed, the Corey-Chaykovsky reaction predominating at higher temperatures. Study of the reactions by means of NMR measurements shows the formation of various cyclic or acyclic as well as ionic Si/S-containing compounds.
Russian Chemical Bulletin, 2014
A comparative study of catalytic activity of palladium complexes with N heterocyclic carbenes in ... more A comparative study of catalytic activity of palladium complexes with N heterocyclic carbenes in the Suzuki-Miyaura reaction was conducted. The studies were carried out for the complexes containing carbenes with five membered rings based on imidazole and imidazoline, and carbenes with expanded six and seven membered rings. The influence of the solvent nature, the base type, and the iodide ions on the catalytic activity of complexes was also examined.
Thermochimica Acta, 2015
The physico-chemical characterization (thermal decomposition under non-and isothermal conditions,... more The physico-chemical characterization (thermal decomposition under non-and isothermal conditions, enthalpy of formation, burning behavior and flame structure) of a new explosive dihydroxylammonium 5,5′-bistetrazole-1,1′-diolate is detailed. Combustion studies have shown that TKX-50 burns slightly faster than HMX and approaches the burning rate of CL 20. The combustion of TKX-50 has been shown to obey mechanism with the leading reaction in the condensed phase. The rates of TKX-50 decomposition in both solid and liquid phases proved to be slightly higher than the corresponding rates of decomposition of RDX. Decomposition of TKX-50 is determined by decomposition of free hydroxylamine formed in the reaction of dissociation of the salt. An intermediate decomposition product is ammonium salt of 5,5′-bis(2-hydroxytetrazole), which further decomposes in the second stage at elevated temperatures. The enthalpy of formation of TKX-50 has been measured with the help of bomb calorimetry, however the resulting value is quite different from the enthalpy reported earlier.
Russian Chemical Bulletin, 2004
Organic chemistry Z 0200 Divalent Silicon, Germanium, and Tin Compounds with Element-Heteroatom B... more Organic chemistry Z 0200 Divalent Silicon, Germanium, and Tin Compounds with Element-Heteroatom Bonds-[principal results and trends in the chemistry of organic derivatives of the title divalent carbon-group elements, selected characteristics and data on synthesis and structure of new type of these compounds; 162 refs.].
The reactions of ylides R 1 3 As=CHR 2 with hexamethyl 2,4,6 trisila and hexamethyl 2,4,6 trigerm... more The reactions of ylides R 1 3 As=CHR 2 with hexamethyl 2,4,6 trisila and hexamethyl 2,4,6 trigermatrithiacyclohexanes afforded betaines R 1 3 As +-CHR 2-SiMe 2-S-(2) (R 1 = Et; R 2 = Ph (a), Me 3 Si (b); R 1 = R 2 = Ph (c)) and Et 3 As +-CH(SiMe 3)-GeMe 2-S-(3), respectively. Betaines 2a,b and 3 were characterized by multinuclear NMR spectroscopy. According to the X ray diffraction data, in the crystals the As +-C-E-Smain chain (E = Si or Ge) of molecules 2a,b and 3 adopts a twisted cis conformation due to strong intramolecular Coulomb interactions between the anionic and cationic centers. The equilib rium geometries of isolated molecules 2a and 3, which were calculated within the framework of the density functional theory (the PBE functional, the TZ2P basis set), are in qualitative agreement with the X ray data. In solutions, betaines 2a (in the absence of Li salts) and 2c (in the presence of LiBr) selectively decomposed according to the Corey-Chaykovsky reaction, which was accompanied by elimination of R 3 As and, probably, the intermediate formation of silathiirane. The subsequent transformation of the latter afforded 2,2,4,4 tetramethyl 5 phenyl 2,4 disila 1,3 dithiolane.
Russian Chemical Reviews, 2014
Russian Chemical Bulletin, 2008
The initiation of ethylene polymerization on L 2 MMe + cations (M = Ge, Sn; L = alkoxy, alkyl, ph... more The initiation of ethylene polymerization on L 2 MMe + cations (M = Ge, Sn; L = alkoxy, alkyl, phenoxyiminate, β diketonate) was studied by the PBE/TZ2P density functional method. It was found that ethylene insertion into the M-C bond of the L 2 MMe + cations is energetically favorable (ΔG 0 =-7.6-13.6 kcal mol-1). The calculated energy barriers to reactions lie in a wide range 39.8 to 75.6 kcal mol-1. The lowest energy barriers were obtained for tin cations bearing hexa and heptafluoroacetylacetonate substituents.
Russian Chemical Reviews, 2014
Polymer Science, Series B, 2020
The polymerization of commercial strained cycloalkene, 5-ethylidene-2-norbornene, in the presence... more The polymerization of commercial strained cycloalkene, 5-ethylidene-2-norbornene, in the presence of Pd-N-heterocyclic carbene complexes (two of which are synthesized for the first time) containing phosphine or pyridine ligands is studied. Upon activation with borate Na + [B(3,5-(CF 3) 2 C 6 H 3) 4)]-, the studied Pd complexes catalyze the polymerization of 5-ethylidene-2-norbornene according to the addition scheme. Polymerization proceeds selectively and involves only the endocyclic (norbornene) double bond of the monomer, while the exocyclic (ethylidene) double bond remains unaffected. Pd-N-heterocyclic carbene complexes with phosphine ligands are inactive in polymerization, while similar complexes with 3-chloropyridine ligands show a higher activity. Two new Pd complexes are synthesized.
Polymer Science, Series C, 2019
Using the commercial derivative of norbornene-5-ethylidene-2-norbornene-a series of three isomeri... more Using the commercial derivative of norbornene-5-ethylidene-2-norbornene-a series of three isomeric homopolymers with different structure of the backbone is synthesized, and the effect of the chain structure on the gas-transport behavior of polynorbornenes is studied. The gas-transport characteristics of the polymers are presented together with data on the conformation properties of molecules of addition and metathesis polynorbornenes. The effect of the structure of side substituents on the equilibrium rigidity of addition polynorbornenes is confirmed by the example of poly(5-ethylidene-2-norbornene) and poly(5vinyl-2-norbornene).
New Journal of Chemistry, 2019
Low energy barriers are found for inter-ring haptotropic rearrangements on large PAH ligands.
ChemInform, 2010
Heteroorganic Betaines. Part 4. Photolysis and Thermolysis of Betaines Containing the + P-C-Si-S ... more Heteroorganic Betaines. Part 4. Photolysis and Thermolysis of Betaines Containing the + P-C-Si-S − Structural Fragment.-Thermal and photolytic decomposition of betaines like (I) follows two main pathways: the Corey-Chaykovsky reaction pattern to give silathiirane intermediate (IX) or a retro-Wittig type reaction to generate silanethione intermediate (X). The former reaction is observed during photolysis of compound (I), and the silathiirane intermediate can be isolated as dimer (II) or trapped with acetone to give oxathiasilolane (XI). Under thermal reaction conditions both pathways are observed, the Corey-Chaykovsky reaction predominating at higher temperatures. Study of the reactions by means of NMR measurements shows the formation of various cyclic or acyclic as well as ionic Si/S-containing compounds.
Russian Chemical Bulletin, 2014
A comparative study of catalytic activity of palladium complexes with N heterocyclic carbenes in ... more A comparative study of catalytic activity of palladium complexes with N heterocyclic carbenes in the Suzuki-Miyaura reaction was conducted. The studies were carried out for the complexes containing carbenes with five membered rings based on imidazole and imidazoline, and carbenes with expanded six and seven membered rings. The influence of the solvent nature, the base type, and the iodide ions on the catalytic activity of complexes was also examined.
Thermochimica Acta, 2015
The physico-chemical characterization (thermal decomposition under non-and isothermal conditions,... more The physico-chemical characterization (thermal decomposition under non-and isothermal conditions, enthalpy of formation, burning behavior and flame structure) of a new explosive dihydroxylammonium 5,5′-bistetrazole-1,1′-diolate is detailed. Combustion studies have shown that TKX-50 burns slightly faster than HMX and approaches the burning rate of CL 20. The combustion of TKX-50 has been shown to obey mechanism with the leading reaction in the condensed phase. The rates of TKX-50 decomposition in both solid and liquid phases proved to be slightly higher than the corresponding rates of decomposition of RDX. Decomposition of TKX-50 is determined by decomposition of free hydroxylamine formed in the reaction of dissociation of the salt. An intermediate decomposition product is ammonium salt of 5,5′-bis(2-hydroxytetrazole), which further decomposes in the second stage at elevated temperatures. The enthalpy of formation of TKX-50 has been measured with the help of bomb calorimetry, however the resulting value is quite different from the enthalpy reported earlier.
Russian Chemical Bulletin, 2004
Organic chemistry Z 0200 Divalent Silicon, Germanium, and Tin Compounds with Element-Heteroatom B... more Organic chemistry Z 0200 Divalent Silicon, Germanium, and Tin Compounds with Element-Heteroatom Bonds-[principal results and trends in the chemistry of organic derivatives of the title divalent carbon-group elements, selected characteristics and data on synthesis and structure of new type of these compounds; 162 refs.].
The reactions of ylides R 1 3 As=CHR 2 with hexamethyl 2,4,6 trisila and hexamethyl 2,4,6 trigerm... more The reactions of ylides R 1 3 As=CHR 2 with hexamethyl 2,4,6 trisila and hexamethyl 2,4,6 trigermatrithiacyclohexanes afforded betaines R 1 3 As +-CHR 2-SiMe 2-S-(2) (R 1 = Et; R 2 = Ph (a), Me 3 Si (b); R 1 = R 2 = Ph (c)) and Et 3 As +-CH(SiMe 3)-GeMe 2-S-(3), respectively. Betaines 2a,b and 3 were characterized by multinuclear NMR spectroscopy. According to the X ray diffraction data, in the crystals the As +-C-E-Smain chain (E = Si or Ge) of molecules 2a,b and 3 adopts a twisted cis conformation due to strong intramolecular Coulomb interactions between the anionic and cationic centers. The equilib rium geometries of isolated molecules 2a and 3, which were calculated within the framework of the density functional theory (the PBE functional, the TZ2P basis set), are in qualitative agreement with the X ray data. In solutions, betaines 2a (in the absence of Li salts) and 2c (in the presence of LiBr) selectively decomposed according to the Corey-Chaykovsky reaction, which was accompanied by elimination of R 3 As and, probably, the intermediate formation of silathiirane. The subsequent transformation of the latter afforded 2,2,4,4 tetramethyl 5 phenyl 2,4 disila 1,3 dithiolane.
Russian Chemical Reviews, 2014
Russian Chemical Bulletin, 2008
The initiation of ethylene polymerization on L 2 MMe + cations (M = Ge, Sn; L = alkoxy, alkyl, ph... more The initiation of ethylene polymerization on L 2 MMe + cations (M = Ge, Sn; L = alkoxy, alkyl, phenoxyiminate, β diketonate) was studied by the PBE/TZ2P density functional method. It was found that ethylene insertion into the M-C bond of the L 2 MMe + cations is energetically favorable (ΔG 0 =-7.6-13.6 kcal mol-1). The calculated energy barriers to reactions lie in a wide range 39.8 to 75.6 kcal mol-1. The lowest energy barriers were obtained for tin cations bearing hexa and heptafluoroacetylacetonate substituents.
Russian Chemical Reviews, 2014