Oxygen Bond Breaking Model

III.2b) Oxygen bond breaking model The ionic character of the bond supposedly in-... 

Pietrzyk, P., Zasada, F., Piskorz, W. et al. (2007) Computational spectroscopy and DFT investigations into nitrogen and oxygen bond breaking and bond making processes in model deNOx and deN20 reactions, Catal. Today, 119, 219. 

To estimate the amount of energy absorbed or released in this reaction, we must compile an inventoiy of all the bonds that break and all the bonds that form. A ball-and-stick model shows that propane contains 8 C—H bonds and 2 C—C bonds. These bonds break in each propane molecule, and one ODO bond breaks in each oxygen molecule. Two CDO bonds form in each CO2 molecule, and two O—H bonds form in each H2 O molecule. In summary ... 

On that basis, conformers A and E can break down by the loss of the axial alkoxy group. Conforrner can undergo a cleavage via the fission of the carbon-oxygen bond of the ring but conforrner cannot break down (no primary electronic effect). Conforrner must therefore be unreactive and this prediction was verified experimentally (38, 50) by studying the reactivity of the tricyclic orthoester 62 (54-56) which is a perfect rigid model for conforrner , as shown by X-ray analysis (57). Indeed, compound 6 was found completely stable under the mild acid conditions that are normally used for the hydrolysis of other cyclic orthoesters. Thus, conforrner is a remarkably unreactive conforrner which must be eliminated. 

A model involving discrete bond breaking was proposed for the formation of the (1x3) surface [107,108]. Surfaces were prepared that exhibited both, the (1x1) termination and the ridges typical for the (1x3) surface. STM and non-contact AFM images showed an intermediate phase, which had a (1x3) symmetry, but did not possess the characteristics of the microfaceted structure. Raza et al. [107] suggested that the bonds labeled a in Fig. 15 are broken, which allows the Ti atoms to relax towards the other rows of bridging oxygen atoms. 

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