Bonds, characterization

Second, the theory of hybrid bond orbitals was utilized recently to discover a new type of chemical bond involving the resonating unshared electron pair.30 31 For example, bis(bistrimethylsilylmethyl) tin(II), (CH3)3 Si 2HCSnCH Si(CH3)3 2, forms dimers in the solid state having a tin-tin bond characterized by resonance of an unshared electron pair or... 

Since mild activation conditions appear to be important, a number of solution activation conditions were tested. PAMAM dendrimers are comprised of amide bonds, so the favorable conditions for refro-Michael addition reactions, (low pH, high temperature and the presence of water) may be able to cleave these bonds. Table 1 shows a series of reaction tests using various acid/solvent combinations to activate the dendrimer amide bonds. Characterization of the solution-activated catalysts with Atomic Absorption spectroscopy, FTIR spectroscopy and FTIR spectroscopy of adsorbed CO indicated that the solution activation generally resulted in Pt loss. Appropriate choice of solvent and acid, particularly EtOH/HOAc, minimized the leaching. FTIR spectra of these samples indicate that a substantial portion of the dendrimer amide bonds was removed by solution activation (note the small y-axis value in Figure 4 relative... 

During conventional polymerizations of both HEMA and DEGDMA, complications resulting from diffusion limitations to termination and propagation are observed. Features such as autoacceleration, autodeceleration and incomplete conversion of double bonds characterize the rate behavior of these polymerizations. As TED is added to the reacting system, the carbon-DTC radical termination reaction is introduced. Diffusion limitations to carbon-DTC radical combination are lower than those to carbon-carbon radical termination as the DTC radical is smaller and much more mobile than a typical polymeric carbon radical. As a result, the cross-... 

A systematic description of bond characteristics in intermetallic phases involves several different approaches. A bond characterization in intermetallics, as related to thermodynamic properties and considerations concerning the stability of intermetallic phases, has been reported by Ellner and Predel (1995). On this subject we observe the peculiar properties of alloys of extraordinary stability formed by... 

Ellner, M. and Predel, B. (1995) Bond characterization from thermodynamic properties. In Intermetallic Compounds. Principles and Practice, eds. Westbrook, J.H. and Fleischer, R.L. (John Wiley Sons Ltd., Chichester), Vol. 1, p. 91. 

Double bonds characterize the basic building blocks of the petrochemical business. Ethylene, for example, is the chemical compound used to make vinyl chloride, ethylene oxide, acetaldehyde, ethyl alcohol, styrene, alpha olefins, and polyethylene, to name only a few. Propylene and benzene, the other big-volume building blocks, also have the characteristic double bonds. 

This chapter shows that the ionic model can not only be presented in terms of chemical bonds characterized by their electrostatic flux, but also that the improbable assumptions of the model are satisfied by the wide range of compounds that conform to the following two conditions ... 

Note that there is nothing wrong widi Eq. (10.45). The entropy of a quantum mechanical harmonic oscillator really does go to infinity as the frequency goes to zero. What is wrong is that one usually should not apply the harmonic oscillator approximation to describe those modes exhibiting the smallest frequencies. More typically than not, such modes are torsions about single bonds characterized by very small or vanishing barriers. Such situations are known as hindered and free rotors, respectively. 

X directions. These directions were chosen because they represent the directions of maximum jt and o bonding. Inspection of this figure shows that the pd-hybridization is strongly localized in the A3 and A2-bands, while the Fermi energy DOS is the result of the bonding characterized by the comparatively flat A4 and A5-bands. 

What kind of carbon-carbon bond characterizes alkanes What kind of carbon-carbon bond characterizes other types of hydrocarbons ... 

R. Binachi et al., Experimental electron density analysis of MN2(CO)10 Metal-metal and metal-ligand bond characterization. Inorg. Chem. 39, 2360-2366 (2000)... 

The complex possesses a novel three-centre two-electron bond, characterized by i.r., H n.m.r., and 11B n.m.r. measurements. The X-ray structure has already been reported.179... 

II) trans-bent conformation (C2V symmetry) —> a double dative bond (characterized by a trans-bent angle k as defined in Scheme 6). 

A cyclic compound containing some number of conjugated double bonds, characterized by an unusually large resonance energy, (pp. 714, 722)... 

Then, analyzing the electron density topology requires the calculation of Vp and of the hessian matrix. After diagonalization one can find the critical points in a covalent bond characterized by a (3, -1) critical point, the positive curvature X3 is associated with the direction joining the two atoms covalently bonded, and the X2, curvatures characterize the ellipticity of the bond by ... 

Hydrogen bonding descriptors, in particular, the ability of an atom in a given environment to be a donor Hd) and acceptor Ha) of a hydrogen bond characterized by the Abraham s constants. " ... 

The cyclic ACN dimer is formed thanks to two weak C—H- -N hydrogen bonds characterized by N- -H bond lengths of 2.633 A and a bond angle of 137.6°. They are manifested spectroscopically by the appearance of two far-IR bands N) and... 

C.-C. Wang, T.-H. Tang, L.-C. Wu, Y. Wang. Topological analyses and bond characterization of 1,3,5,7-tetra-tert-butyl-i-indacene a weak Cj s-H H-Cj 2-type dihydrogen interaction. Acta Cryst. A 60, 488-493 (2004). 

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