in this paper, we investigate various kinds of extensions of twin-good rings. moreover, we prove that every element of an abelian neat ring r is twin-good if and only if r has no factor ring isomorphic to z2  or z3. the main result of [24] states some conditions that any right self-injective ring r is twin-good. we extend this result to any regular baer ring r by proving that every element of a...

Coordination of the carbocyclic ring of hydroquinones to electrophilic transition-metal fragments such as Mn(CO)3+ and Rh(COD)+ produces stable pi-bonded eta6-complexes that are activated to facile reversible deprotonation of the -OH groups. The deprotonations are accompanied by electron transfer to the transition metal, which acts as an internal oxidizing agent or electron sink. With manganese...

We present an atomistic simulation of the cobalt hexammine(ii/iii) self-exchange reaction using path integral (PI) methods. We construct a simple force field for the system in its reactant state that includes parameters for both atom-atom interactions, and interactions with an explicit transferring electron represented in the PI framework. We then calculate the outer sphere free energy barrier ...

Research interest in graphene, a two-dimensional crystal consisting of a single atomic plane of carbon atoms, has been driven by its extraordinary properties, including charge carriers that mimic ultra-relativistic elementary particles. Moreover, graphene exhibits ballistic electron transport on the submicrometre scale, even at room temperature, which has allowed the demonstration of graphene-b...

Complexes of PheAla and AlaPhe with alkali metal ions Na(+) and K(+) are generated by electrospray ionization, isolated in the Fourier-transform ion cyclotron resonance (FT-ICR) ion trapping mass spectrometer, and investigated by infrared multiple-photon dissociation (IRMPD) using light from the FELIX free electron laser over the mid-infrared range from 500 to 1900 cm(-1). Insight into structur...

Replacement of halide from N-(haloboryl)formamidines for the weakly coordinating anion [B(C(6)F(5))(4)](-), using [Et(3)Si(toluene)](+)[B(C(6)F(5))(4)](-), induces a ring closure leading to the cationic four-pi-electron four-membered heterocycles [HC(N-2,6-diisopropylphenyl)(2)BR](+) [R = N(i-Pr)(2), Ph]. Subsequent deprotonation of the B-amino derivative affords the corresponding N-heterocycli...

Phosphatidylinositol polyphosphates (PI-PPs) have been shown to mediate a large variety of physiological processes by attracting proteins to specific cellular sites. Such site-specific signaling requires local accumulation of PI-PPs, and in light of the rich headgroup functionality, it is conceivable that hydrogen bond formation between adjacent headgroups is a contributing factor to the format...

A comparison of the (13)C nuclear magnetic resonance chemical shifts of some 15,16-dialkyl-15,16-dihydropyrenes with the corresponding 15,16-dialkyl-2,7,15,16-tetrahydropyrenes provides a measure of the effect of ring current on carbon-13 chemical shifts in which other effects may be expected to be negligibly small. The general conclusion is that the absolute magnitude of the ring-current effec...

Two heterocyclic cyclopentadienyl analogs with a CB2N2 skeleton, 4-methyl-1,2,3,5-tetraphenyl-1,2-diaza-3,5-diborolidine and 4-methyl-3,5-dimethylamino-1,2-diphenyl-1,2-diaza-3,5-diborolidine were prepared through cyclocondensation of the corresponding 1,1-bis(organochloroboryl)ethane with 1,2-diphenylhydrazine. The former diazadiborolidine featured a cyclopentadiene-like structure with short B...

Computations provide insight to the stability and isomeric possibilities of thiotropocin, tropodithietic acid, and troposulfenin. Thiotropocin and tropodithietic acid contain a flat 7-membered ring and delocalized pi-bonds similar to those of tropylium ion (C(7)H(7)(+)). Troposulfenin is far less stable; it contains a puckered tropone ring and localized bonds similar to 1,3,5-cycloheptatriene. ...