Syntheses and structures of magnesium,calcium, europium,gallium, and zinc complexes with bis(imino)acenaphthene ligands

The reduction of 1,2-bis(trimethylsilylimino)acenaphthene and 1,2-bis{[3,5-bis(trifluoromethylphenyl)]imino}acenaphthene with metals gave magnesium, calcium, europium, zinc, and gallium complexes containing radical-anion and dianionic ligands of the 1,2-diiminoacenaphthene type. Their structures were studied by ¹H NMR, ESR, and/or single-crystal X-ray analysis. Some chemical transformations of the complexes were carried out.     

Titanium(<Emphasis Type="SmallCaps">IV</Emphasis>) chloride complexes with chiral tetraaryl-1,3-dioxolane-4,5-dimethanol ligands as a new type of catalysts of ethylene polymerization

Titanium complexes of chiral ligands, (4R,5R)-2,2-dimethyl-α,α,α′,α′-tetraphenyl-1,3-dioxolane-4,5-dimethanol and its structural analogs, activated by polymethylalumoxane catalyze ethylene polymerization with an activity from 3 to 530 (kg polyethylene) (mol Ti h atm)⁻¹. An increase in the bulk of the aryl substituents results in a decrease in the catalytic activity of the complexes. Published in Russian in Izvestiya Akademii Nauk. Seriya Khimicheskaya, No. 10, pp. 2275–2280, October, 2005.     

Synthesis of chiral polydentate ligands and the use of their titanium complexes as pre-catalysts for the asymmetric trimethylsilylcyanation of benzaldehyde

A number of polydentate ligands based on enantiomerically pure binaphthol have been synthesized. The ligand complexes with titanium isopropoxide were used as catalysts for the asymmetric addition of trimethylsilyl cyanide to benzaldehyde. A fragment with axial chirality is responsible for the configuration of O-trimethylsilyl cyanohydrin product. In the case of the optimum ligand based on (R)-binaphthol and (S)-leucinol, an enantiomeric excess of 86% and quantitative yield were achieved in 4 h. Published in Russian in Izvestiya Akademii Nauk. Seriya Khimicheskaya, No. 9, pp. 1946–1953, September, 2008.     

Synthesis,structure, and properties of <Emphasis Type="Italic">N</Emphasis>-(nitramino)phthalimide

N-(Nitramino)phthalimide R₂N-NHNO₂ (R₂NH is phthalimide) was synthesized by nitration of N-aminophthalimide with nitronium tetrafluoroborate. The structure of this compound was established by X-ray diffraction and confirmed by ¹H, ¹³C, and ¹⁴N NMR spectroscopy. The methylation of this compound with diazomethane affords a mixture of N-methyl (R₂N-NMeNO₂) and O-methyl (R₂N-N=N(O)OMe) isomers. The latter compound contains the previously unknown high-nitrogen-oxygen fragment. The thermal decomposition of N-(nitramino)phthalimide in vacuo at 80–100 °C gives 2H-3,1-benzoxazine-2,4(1H)-dione (isatoic anhydride) as the major product. Published in Russian in Izvestiya Akademii Nauk. Seriya Khimicheskaya, No. 3, pp. 625–630, March, 2008.     

Synthesis, catalytic activity, and photophysical properties of 5,6-membered Pd and Pt SCS'-pincer complexes based on thiophosphorylated 3-amino(hydroxy)benzoic acid thioanilides

Novel unsymmetrical SCS'-pincer ligands, 1-[PhNHC(S)]-3-[Ph(2)P(S)NH]-C(6)H(4) (3) and 1-[PhNHC(S)]-3-[Ph(2)P(S)O]C(6)H(4) (7), bearing a thiocarbamoyl moiety in combination with thiophosphorylamino- and thiophosphoryloxy-donating groups, respectively, were obtained via thiophosphorylation of 3-amino- and 3-hydroxy-benzoic acid (thio)anilides 1 and 6. Direct cyclometallation of the central benzene ring in the ligands 3 and 7 in reaction with (PhCN)(2)MCl(2) (M = Pd, Pt) as a metal precursor afforded κ(3)-SCS'-hybrid pincer complexes 8, 9 with 5- and 6-membered fused metallacycles in good to high yields (67-95%). The complexes 8 and 9 were characterized by multinuclear NMR ((31)P, (1)H, (13)C) and IR spectroscopy as well as single-crystal X-ray crystallography. Palladium complexes 8a and 9a were shown to be active catalysts for the Suzuki-Miyaura cross-coupling reaction. In the solid state the ligands 3 and 7 as well as their Pt(II) and Pd(II) complexes 8 and 9 are luminescent at 300 K. The emission of the complexes has the different origin depending on the metal nature.     

Structural tautomerism of 4-acylpyrazolone schiff bases and crystal structure of 5-methyl-2-phenyl-4-{1-[(pyridin-2-ylmethyl)-amino]-ethylidene}-2,4-dihydro-pyrazol-3-one

The Schiff base derivatives prepared from 4-acetyl-5-methyl-2-phenyl-2,4-dihydro-pyrazol-3-one and alkyl amines are shown to remain exclusively in the amine-one(I) tautomeric form in chloroform solutions at room temperature using a combination of ¹H, ¹³C, APT, COSY, HMQC, and HMBC NMR spectroscopic methods. The crystal structure of 5-methyl-2-phenyl-4-{1-[(pyridin-2-ylmethyl)-amino]-ethylidene}-2,4-dihydro-pyrazol-3-one showed that this 4-acylpyrazolone Schiff base stays in the amine-one(I) form in the solid state as well, and the solid state structure supports the fact that strong hydrogen bonding between amine hydrogen and the pyrazolone C₃ carbonyl oxygen helps to stabilize the amine-one(I) tautomer.