Search results for "boori"

Computational thermochemistry: extension of Benson group additivity approach to organoboron compounds and reliable predictions of their thermochemica…

2022

High-level computational data for standard gas phase enthalpies of formation, entropies, and heat capacities are reported for 116 compounds of boron. A comparison of the results with extant experimental and computational benchmark values reveals important trends and clear outliers. Recommendations are made to revise some of the key quantities, such as the enthalpies of formation of orthoboric acid, trimethylthioborate, and triphenylborane, the last of which is found to be considerably in error. The uncertainties associated with the experimental values are found to exceed those of high-level calculations by a clear margin, prompting the redetermination of Benson group additivity contribution…

Neutron halos in the excited states of 12B

2018

The differential cross sections of the 11B(d,p) 12B reaction leading to formation of the 1+ ground state and the 0.95-MeV 2+, 1.67-MeV 2−, 2.62-MeV 1−, 2.72-MeV 0+, and 3.39-MeV 3− excited states of 12B are measured at Ed = 21.5 MeV. The analysis of the data is carried out within the coupled-reaction-channels method for the direct neutron transfer and the Hauser-Feshbach formalism of the statistical compound-nucleus model. The spectroscopic factors, asymptotic normalization coefficients, and rms radii of the last neutron in all states studied are deduced. The existence of the neutron halos in the 1.67-MeV 2− and 2.62-MeV 1− states is found, consistent with the earlier published data. New in…

Boorin määritysmenetelmiä vesistä, kasveista, maaperästä, tuhkista ja lannoitteista

2012

Tutkielmassa on tarkasteltu boorin määritysmenetelmiä vesistä, maaperästä, kasveista, lannoitteista ja tuhkista. Tutkielma on jaettu esikäsittelyyn, erotusmenetelmiin ja määritysmenetelmiin. Esikäsittelyssä on huomioitu maaperän, lannoitteiden ja tuhkien kohdalla biosaatavuus ja kokonaismäärä. Kasvien ja vesien kohdalla on tarkasteltu kokonaismäärää. Boorin eristäminen on voitu tehdä uuttaen orgaaniseen faasiin joko diolien avulla tai orgaanisen kationin avulla tetrafluoroboraattina. Boori tislautuu metyyliboraattina metanolin ja rikkihapon seoksessa. Ioninvaihdossa on boori voitu kvantitaviivisesti eristää ioninvaihtohartsilla emäksisissä olosuhteissa. On myös mahdollista hyödyntää muita h…

Unusual B4N2C2 Ligand in a Ruthenium Pseudo-Triple-Decker Sandwich Complex Displaying Three Reversible Electron-Transfer Steps

2008

Open, sesame: The reaction of a heterobicyclic pentalenediyl-like Me2Ph4B4N2C2 dianion with [{(C5Me5)RuCl}4] cleaves the N[BOND]N bond of the ligand and affords a pseudo-triple-decker sandwich complex containing a B4N2C2 middle deck (see picture). This eight-membered ring features nearly linear B-N-B moieties and brings the ruthenium centers unusually close. Cyclic voltammetry indicates efficient electron delocalization over the framework. peerReviewed

Divergent reactivity of nucleophilic 1-bora-7a-azaindenide anions

2017

The reactions of 1-bora-7a-azaindenide anions, prepared in moderate to excellent yields by reduction of the appropriate 1-bora-7a-azaindenyl chlorides with KC8 in THF, with alkyl halides and carbon dioxide were studied. With alkyl halides (CH2Cl2, CH3I and BrCH(D)CH(D)tBu), the anions behave as boron anions, alkylating the boron centre via a classic SN2 mechanism. This was established with DFT methods and via experiments utilizing the neo-hexyl stereoprobe BrCH(D)CH(D)tBu. These reactions were in part driven by a re-aromatization of the six membered pyridyl ring upon formation of the product. Conversely, in the reaction of the 1-bora-7a-azaindenide anions with CO2, a novel carboxylation of …

Icosahedral carboranes as scaffolds for congested regioselective polyaryl compounds : the distinct distance tuning of C-C and its antipodal B-B

2019

Four-fold aryl substituted o-carborane derivatives with defined patterns of substitution at the antipodal region of the cluster carbon atoms have been achieved. It is proven that this region is congested but lacks steric hindrance. Also, the two antipodal sites Cc-Cc and B9-B12 are affected very distinctly by electron donor substituents. peerReviewed

Cross-coupling reactions of organoborons with organic halides

2011

Cluster rotational bands in 11B

2016

Differential cross-sections of 11B+α inelastic scattering at E(α) = 65 MeV leading to most of the known 11B states at excitation energies up to 14 MeV were measured [1]. The data analysis was done using Modified diffraction model (MDM) [2] allowing determining radii of excited states. Radii of the states with excitation energies less than ∼ 7 MeV coincide with the radius of the ground state with an accuracy not less than 0.1 - 0.15 fm. This result is consistent with traditional view on shell structure of low-lying states in 11B. Most of the observed high-energy excited states are distributed among four rotational bands. Moments of inertia of band states are close to the moment of inertia of…

Assembly of a planar, tricyclic B4N8 framework with s-indacene structure

2007

A neutral, formally 16π-electron, tricyclic tetrahydrazidotetraborane was obtained in a two-step procedure involving self-assembly of a dilithiodiborate with B4N8 framework and subsequent oxidation of the phenylborate moieties to boranes and biphenyl using Fe(II) as an oxidant. peerReviewed

Approaching a “naked” boryl anion: amide metathesis as a route to calcium, strontium, and potassium boryl complexes

2020

Abstract Amide metathesis has been used to generate the first structurally characterized boryl complexes of calcium and strontium, {(Me3Si)2N}M{B(NDippCH)2}(thf)n (M=Ca, n=2; M=Sr, n=3), through the reactions of the corresponding bis(amides), M{N(SiMe3)2}2(thf)2, with (thf)2Li‐ {B(NDippCH)2}. Most notably, this approach can also be applied to the analogous potassium amide K{N(SiMe3)2}, leading to the formation of the solvent‐free borylpotassium dimer [K{B(NDippCH)2}]2, which is stable in the solid state at room temperature for extended periods (48 h). A dimeric structure has been determined crystallographically in which the K+ cations interact weakly with both the ipso‐carbons of the flanki…