Water-soluble N-oxyl compounds-mediated electrooxidation of alcohols in water: a prominent access to a totally closed system

Electrooxidation of alcohols in water involving water-soluble N-oxyl compounds (WS-TEMPOs) proceeded smoothly to afford the corresponding ketones and aldehydes in good yields. Notably, most of WS-TEMPOs in water remained intact after the electrolysis. The aqueous solution containing WS-TEMPOs was recovered easily and repeatedly used for the electrooxidation of alcohols, offering a totally closed system.     

Ruthenium Complex-Controlled Catalytic N-Mono- or N,N-Dialkylation of Heteroaromatic Amines with Alcohols

Heteroaromatic amines were N-alkylated with primary alcohols at 150-200 degrees C in the presence of a catalytic amount of various ruthenium complexes to give the corresponding monoalkylated and dialkylated amines in good to high yields. For example, 2-aminopyridine reacted with an excess of ethanol at 180 degrees C for 20 h in the presence of dichlorotris(triphenylphosphine)ruthenium [RuCl(2)(PPh(3))(3)] to give 2-(ethylamino)pyridine (1) and 2-(diethylamino)pyridine (2) in 9% and 70% yields, respectively. On the other hand, when (eta(4)-1,5-cyclooctadiene)(eta(6)-1,3,5-cyclooctatriene)ruthenium [Ru(cod)(cot)] was used as a catalyst, even in the presence of excess ethanol, 1 was obtained in 85% yield with high selectivity. The addition of tertiary phosphines and phosphites to Ru(cod)(cot) increased the yield of the dialkylated amine.     

Synthesis and electrochemical properties of bis(bipyridine)ruthenium(II) complexes bearing pyridinyl- and pyridinylidene ligands induced by cyclometalation of N′-methylated bipyridinium analogs

Ruthenium complexes with bipyridine-analogous quaternized (N,C) bidentate ligands [RuL(bpy)₂](PF₆)₂ (bpy = 2,2′-bipyridine, (1), L = L¹ = N′-methyl-2,4′-bipyridinium; (2), L = L² = N′-methyl-2,3′-bipyridinium) were synthesized and characterized. The structure of complex 2 was determined by the X-ray structure analysis. The ¹³C{¹H} NMR spectroscopic and cyclic voltammetric studies indicate that the coordination modes of these ligands are quite different, that is, the C-coordinated rings of (N,C)-ligands in 1 and 2 are linked to ruthenium(II) with a pyridinium manner and a pyridinylidene one, respectively. The ligand-localized redox potentials of 1 and 2 also revealed the substantial difference in the electron donating ability of both ligands.     

Numerical Analysis of Weakly Relativistic Large Orbit Gyrotron with Permanent Magnet System

High-harmonic gyro-devices with axis-encircling electron beams known as large orbit gyrotrons (LOG) represent an appealing alternative to the conventional gyrotrons. In this paper we investigate the feasibility of such device operating with low current and low energy electron beams formed by a novel electron gun with a permanent magnet system. The results from the numerical experiments indicate the possibility to excite TE₄₁ mode at fourth harmonic of the cyclotron frequency. Simulations predict generation of microwave radiation with frequency 104 GHz and output power near 1 kW.     

A Symmetrically Bridging Triarylsilyl Ligand in a Dinuclear Rhodium Complex: Synthesis and Structure of [LRh(H)(µ-Cl)(µ-SiAr2)(µ-SiAr3)Rh(H)L] (Ar=Ph,p-FC6H4; L=PiPr3)

Simply warming solutions of the dinuclear complexes 1 provides novel complexes 2 [Eq. (a); Ar = Ph, p-FC₆H₄; L = PiPr₃], which contain a bridging triarylsilyl ligand and show unusual thermal stability. Compounds with this type of symmetric structure are of interest as models of the transition state for the migration of tertiary silyl groups in a bimetallic framework.