Preparation of Poly(methyl methacrylate) Nanoparticles 15–50 nm in Diameter from Submicrometer-Sized Latex Particles

Russian Journal of Applied Chemistry - A procedure was developed for preparing poly(methyl methacrylate) nanoparticles of 15–50 nm size from coarser (200–300 nm) polymer latex particles...     

Synthesis and structures of silicon-, germanium-, and tin-containing imido-alkyl molybdenum complexes (ArN)2Mo(CH2EMe3)2 (E = Si, Ge, Sn)

New silicon-, germanium-, and tin-containing imido-alkyl molybdenum complexes (ArN)₂Mo(CH₂EMe₃)₂ (Ar is 2,6-diisopropylphenyl; E = Si (1), Ge (2), Sn (3)) were prepared in the crystalline state in 58–66% yields by the reactions of the (ArN)₂MoCl₂(DME) complex with alkyllithium derivatives Me₃ECH₂Li (E = Si or Ge) or the Grignard reagents Me₃ECH₂MgCl (E = Ge or Sn). The structures of complexes 1–3 and the known analog (ArN)₂Mo(CH₂Bu^t)₂ (4) were established by X-ray diffraction analysis. Complexes 1–3 were found to be isostructural. The coordination environment about the Mo atom can be described as a distorted tetrahedron. Complex 4 has a similar structure. The Mo-C distance tends to decrease with increasing electron donating ability of the EMe₃ group.__________Published in Russian in Izvestiya Akademii Nauk. Seriya Khimicheskaya, No. 3, pp. 597–600, March, 2005.     

Synthesis and catalytic properties of polynuclear molybdenum silicon-containing carbene complexes

The molybdenum silicon-containing carbene complexes PhMe₂Si—CH=Mo(NAr)(OR)₂ (1), Ph₂Si[CH=Mo(NAr)(OR)₂]₂ (2), and (RO)₂(ArN)Mo=CH—(SiMe₂)₂—CH=Mo(NAr)(OR)₂ (Ar = 2,6-Prⁱ ₂C₆H₃; R = CMe₂CF₃) were synthesized by the reaction of the R′— CH=Mo(NAr)(OR)₂ compounds (R′ = Bu^t or PhMe₂C) with silicon-containing vinyl reagents. The structures of complexes 1 and 2 and the known PhMe₂C—CH=Mo(NAr)(OCMe₂CF₃)₂ compound were established by X-ray diffraction. The catalytic properties of the silicon-containing carbene complexes in homometathesis of hex-1-ene and metathesis polymerization of cyclooctene were studied. The catalytic activity of these complexes and the stereoregularity of the resulting polyoctenamers substantially depend on the nature of the substituent at the carbene carbon atom. Published in Russian in Izvestiya Akademii Nauk. Seriya Khimicheskaya, No. 2, pp. 247–252, February, 2007.     

Terbium-containing copolymers based on the norbornene functional derivatives. Synthesis, photoluminescent and electroluminescent properties

New carbazole- and terpyridine- containing norbornene derivatives were synthesized and structurally characterized. On the basis of these compounds by the method of metathesis polymerization copolymers were obtained with carbazole and terpyridine fragments in side chains. The synthesized copolymers react with terbium pyrazolonate complex to form the terbium-containing polymeric materials exhibiting the metalcentered photo- and electroluminescence.     

Regularities of ring-opening metathesis polymerization of cyclooctene in the presence of molybdenum catalysts

At the initial stages the polymerization of cis-cyclooctene in the bulk with the catalysts Me₃C-CH=Mo(NAr)(OCMe₂CP₃)₂, PhMe₂C-CH=Mo(NAr)(OCMe₂CP₃)₂, Me₃Si-CH=Mo(NAr)(OCMe₂CP₃)₂, and PhMe₂Si-CH=Mo(NAr)(OCMe₂CP₃)₂ predominantly affords cis-polyoctenamers. The content of the trans- units in the polymer increases with an increase in the conversion. The sharpest increase in the trans- unit content observed for conversions higher than 80% is related to secondary metathesis reactions. The number-average molecular weights of the polymers increase linearly with the conversion. At conversions above 80% the molecular weights decrease due to the increasing contribution of chain transfer reactions. Polyoctenamers with the increased content of trans- units crystallize in two modifications.     

Carbene complexes of molybdenum and tungsten Et3E-CH=M(NAr)(OR)2 (M = Mo, W; E = Si, Ge) and π-complex of molybdenum (RO)2(ArN)Mo(CH2=CH-GeEt3). Synthesis and catalytic properties

The heteroelement-containing alkylidene imide complexes with molybdenum and tungsten Et₃SiCH=Mo(NAr)(OR)₂ (I), Et₃ ECH=W(NAr)(OR)₂ (E = Si (II), Ge (III); Ar = 2,6-i-Pr₂C₆H₃; R=CMe₂ CF₃) and π-complex (RO)₂(ArN)Mo(CH₂=CH-GeEt₃) (IV) were synthesized by the reaction of Alkyl-CH=M(NAr) (OR)₂ (M=Mo, W; Alkyl = t-Bu, PhMe₂C) with organosilicon and organogermanium vinyl reagents Et₃ECH=CH₂ (E = Si, Ge). The structure of compounds I–III was determined by X-ray diffraction (XRD). The complexes I–IV are active initiators of metathesis polymerization of cycloolefins.     

Cyclometallated iridium(III) complex with the norbornene-substituted pyrazolonate ligand and related copolymers: syntheses, structures, and photophysical properties

New cyclometallated iridium(III) complex (NBEpz)Ir(Ppy)₂ · 2CH₂Cl₂ (I) (NBEpzH is 1-phenyl-3-methyl-4-(5-bicyclo[2.2.1]hept-5-en-2-yl)-5-pyrazolone, PpyH is 2-phenylpyridine) is synthesized and structurally characterized. Compound I undergoes metathesis polymerization and forms new iridium-containing copolymers. The photophysical properties of complex I and related copolymers are studied.     

Synthesis and luminescent properties of iridium(III) ionic binuclear complexes with 1,4-bis[2-(2-pyridyl)benzimidazolato]butane as a bridging ligand

New ionic binuclear complexes of iridium(III) containing 1,4-bis[2-(2-pyridyl)benzimidazolato]butane as a bridging ligand were synthesized. These compounds exhibit intensive photo- and electroluminescence of yellow-green, green-yellow, and pink colors. The maximal electroluminescence brightness was 4565 cd/m².     

Effect of the nature of carbene fragments in the tungsten complexes PhMe2E-CH=W(NAr)(OR′)2 and Me3E-CH=W(NAr)(OR′)2 (E = C, Si) on their catalytic properties in olefin metathesis reactions

Catalytic properties of the silicon-containing carbene complexes of tungsten Me₃Si-CH=W(NAr)(OR′)₂(1) and PhMe₂Si-CH=W(NAr)(OR′)₂ (2) and their hydrocarbon analogs Me₃C-CH=W(NAr)(OR′)₂ (3) and PhMe₂C-CH=W(NAr)(OR′)₂ (4) (Ar = 2,6-Prⁱ ₂C₆H₃, R′ = CMe₂CF₃) were studied in homometathesis of hex-1-ene, metathesis polycondensation of deca-1,9-diene, and ring opening metathesis polymerization of cyclooctene. The nature of the carbene fragment in the tungsten catalysts substantially affects their catalytic activity. Silicon-containing catalysts 1 and 2 were found to be 3−5 times less active than their hydrocarbon analogs 3 and 4. Metathesis polymerization of cyclooctene in the bulk with initiators 1–4 completed within a few minutes to form a block. Stereoregularity of the formed polyoctenamers depends to a considerable extent on the nature of the carbene fragments in the starting initiators. Initiators 1–2 lead to polyoctenamers mainly containing the cis-units, whereas the use of complexes 3 and 4 affords polyoctenamers mainly containing the trans-units. The structures of novel compound 2 and known complexes 1, 3, and 4 were determined by X-ray diffraction analysis. Published in Russian in Izvestiya Akademii Nauk. Seriya Khimicheskaya, No. 9, pp. 1840–1845, September, 2008.