Synthesis of new acyclic aminophosphites and their chelate complexes with rhodium(i) and palladium(ii)

New acyclic aminophosphites (RO)₂POCH₂CH₂NMe₂ (PN) (R=Et, Prⁱ, or adamantyl) characterized by various steric requirements of the phosphorus center were synthesized. The reactions of the aminophosphites with Pd(COD)Cl₂ (COD is 1,5-cyclooctadiene) and [Rh(CO)₂Cl]₂ afforded the stable chelate mononuclear complexes PdCl₂(PN) and RhClCO(PN), respectively. The structures of the resulting compounds were established by¹H,¹³C, and³¹P NMR and IR spectroscopy, X-ray diffraction analysis, laser and plasma desorption mass spectrometry, X-ray photoelectron spectroscopy, and sedimentation analysis.     

Bispidine Platform as a Tool for Studying Amide Configuration Stability

In this work, the solution conformations of seventeen 3,7-diacyl bispidines were studied by means of NMR spectroscopy including VT NMR experiments. The acyl groups included alkyl, alkenyl, aryl, hetaryl, and ferrocene moieties. The presence of syn/anti-isomers and their ratios were estimated, and some reasons explaining experimental facts were formulated. In particular, all aliphatic and heterocyclic units in the acylic R(CO) fragments led to an increased content of the syn-form in DMSO-d₆ solutions. In contrast, only the anti-form was detected in DMSO-d₆ and CDCl₃ in the case when R = Ph, ferrocenyl, (R)-myrtenyl. In the case of a chiral compound derived from the natural terpene myrtene, a new dynamic process was found in addition to the expected inversion around the amide N-C(O) bond. Here, rotation around the CO-C=C bond in the acylic R fragment was detected, and its energy was estimated. For this compound, ΔG for amide N-C(O) inversion was found to be equal to 15.0 ± 0.2 kcal/mol, and for the rotation around the N(CO)–C^2′ bond, it was equal to 15.6 ± 0.3 kcal/mol. NMR analysis of the chiral bispidine-based bis-amide was conducted for the first time. Two X-ray structures are reported. For the first time, the unique syn-form was found in the crystal of an acyclic bispidine-based bis-amide. Quantum chemical calculations revealed the unexpected mechanism for amide bond inversion. It was found that the reaction does not proceed as direct N-C(O) bond inversion in the double-chair (CC) conformation but rather requires the conformational transformation into the chair–boat (CB) form first. The amide bond inversion in the latter requires less energy than in the CC form.     

Diastereoselective cycloalkylation of phosphoryl and thiophosphoryl acetonitriles by α,ψ‐dihalogenalkanes under phase transfer catalysis conditions

Cycloalkylation of phosphoryl and thiophosphoryl acetonitriles 2 by α,ψ‐dihalogenalkanes was found to proceed diastereoselectively under phase transfer catalytic conditions yielding 1‐(phosphoryl)‐2‐methyl‐cycloalkane carbonitriles as trans‐isomers with identical configuration of asymmetric cyclic carbon atoms (R_C^* R_C^*). In the case of additional asymmetric phosphorus atom in the starting substrate, trans‐isomers are formed as a mixture of diastereomers differing in the configuration of the phosphorus atom (S_P^* R_C^* R_C^* and R_P^* R_C^* R_C^*). © 2006 Wiley Periodicals, Inc. Heteroatom Chem 17:13–21, 2006; Published online in Wiley InterScience ( www.interscience.wiley.com ). DOI 10.1002/hc.20186     

The influence of ionic liquid's nature on free radical polymerization of vinyl monomers and ionic conductivity of the obtained polymeric materials

Various 1,3‐dialkylimidazolium and tetraalkylphosphonium ionic liquids (ILs), including novel ones, have been studied as reaction media for free radical polymerization of methyl methacrylate (MMA), acrylonitrile (AN) and 1‐vinyl‐3‐ethylimidazolium salts (ViEtIm⁺)Y^?. The influence of IL's nature upon the polymer formulation was investigated. The use of different ionic liquids allows not only to obtain the polymers with high molecular weight (PMMA, up to 5,770,000 g/mol; PAN, up to 735,000 g/mol and poly[(ViEtIm⁺)Y^?], up to 1,130,000 g/mol) in high yields, but also to control the polymerization rate and molecular mass. The physicochemical characteristics, including mechanical properties, thermal stability and heat‐resistance of the obtained polymers were studied in order to compare with those of polymers prepared in a traditional media. It was found that elongation, tensile modulus and strength of PAN, which was synthesized in ionic liquid, are reliatively higher. The influence of IL's nature upon their ionic conductivity and the formation of conductive polymers from molten‐salt‐type vinyl monomers was investigated. Molecular design of the polymers simultaneously with the influence of IL's nature in order to achieve higher ionic conductivity is discussed. Flexible, transparent polymer films, obtained in different ways, show relatively high ionic conductivity (of about 10^?5 S cm^?1 at 20°C). Copyright © 2006 John Wiley & Sons, Ltd.     

The "hockey sticks" effect revisited: the conformational and electronic properties of 3,7-dithia-1,5-diazabicyclo[3.3.1]nonane from the QTAIM perspective

The conformational effects in bicyclo[3.3.1]nonanes, while thoroughly studied, have not yet received the full theoretical explanation. R. F. W. Bader's quantum theory of atoms in molecules presents unique opportunities for studying the stereoelectronic interactions (SEI) and weak intramolecular bonding leading to these effects. Here, we report the study of 3,7-dithia-1,5-diazabicyclo[3.3.1]nonane by means of the topological analysis of the calculated (MP2(full)/6-311++G**) and experimental (X-ray derived) charge density to reveal the origins of the so-called "hockey sticks" effect observed in similar compounds. A new explanation of the relative stability of bicyclo[3.3.1]nonane conformers based on the analysis of the QTAIM atomic energies is given. The H···H and S···S interactions in bicyclo[3.3.1]nonane and its dithia derivatives are shown to be significant factors contributing to the differences in the relative stability of the conformers.     

Simple Synthesis of Ruthenium π Complexes of Aromatic Amino Acids and Small Peptides

The interaction of [Ru(η⁶‐C₁₀H₈)(Cp)]⁺ (Cp=C₅H₅) with aromatic amino acids (L ‐phenylalanine, L ‐tyrosine, L ‐tryptophane, D ‐phenylglycine, and L ‐threo‐3‐phenylserine) under visible‐light irradiation gives the corresponding [Ru(η⁶‐amino acid)(Cp)]⁺ complexes in near‐quantitative yield. The reaction proceeds in air at room temperature in water and tolerates the presence of non‐aromatic amino acids (except those which are sulfur containing), monosaccharides, and nucleotides. The complex [Ru(η⁶‐C₁₀H₈)(Cp)]⁺ was also used for selective labeling of Tyr and Phe residues of small peptides, namely, angiotensin I and II derivatives.     

Synthesis of unsymmetrical 4-oxo-2-vinyl-4H-chromene-3-carbonitrile dyes via Knoevenagel reaction

New 4-oxo-2-vinyl-4H-chromene-3-carbonitrile derivatives have been synthesized by the Knoevenagel reaction of 2-methyl-4-oxo-4H-chromene-3-carbonitrile with aromatic and heteroaromatic aldehydes. Spectral properties of the obtained compounds have been studied.     

Sandwich iridium complexes with the monoanionic carborane ligand [9-SMe2-7,8-C2B9H10]−

The reaction of the [(η-9-SMe₂-7,8-C₂B₉H₁₀)IrBr₂]₂ complex with Tl[Tl(η-7,8-C₂B₉H₁₁)] afforded the iridacarborane compound (η-9-SMe₂-7,8-C₂B₉H₁₀)Ir(η-7,8-C₂B₉H₁₁). The cationic complex [Cp*Ir(η-9-SMe₂-7,8-C₂B₉H₁₀)]⁺PF₆ ⁻ (5 · PF₆, Cp* is pentamethylcyclopentadienyl) was synthesized by the reaction of [Cp*IrCl₂]₂ with Na[9-SMe₂-7,8-C₂B₉H₁₀]. The structures of (η-9-SMe₂-7,8-C₂B₉H₁₀)Ir(η-cod) (cod is 1,5-cyclooctadiene) and 5 · PF₆ were established by X-ray diffraction. Published in Russian in Izvestiya Akademii Nauk. Seriya Khimicheskaya, No. 1, pp. 81–84, January, 2006.