Terminal oxygen atoms

Figure 14 Mechanism of oxygen elimination from the structure of BajYC Oy 0. (a) As an effect of temperature increase, atom A may jump into position A (b) As a consequence of this shift, atom B may jump into position B, C into C etc., thus causing a correlated motion of the oxygen atoms terminating with the expulsion of half oxygen atom from the structure (c) Atom C now may jump into positions C or C" generating a second cascade...

Phosphorus Pentoxide (P4O10) In this each P atom forms three bonds to the oxygen atoms and also an additional coordinate bond with an oxygen atom. Terminal PO bond is much shorter than PO bond. It shows that there is a considerable pp-dp back bonding because of the lateral overlap of full p-orbitals on oxygen with empty Jp-orbitals on phosphorus. 

Restructuring of a surface may occur as a phase change with a transition temperature as with the Si(OOl) surface [23]. It may occur on chemisorption, as in the case of oxygen atoms on a stepped Cu surface [24]. The reverse effect may occur The surface layer for a Pt(lOO) face is not that of a terminal (100) plane but is reconstructed to hexagonal symmetry. On CO adsorption, the reconstruction is lifted, as shown in Fig. XVI-8. 

O Protonation of the hydroperoxy group on the terminal oxygen atom gives an oxonium ion. . . ... 

Phosphorus(V) oxide, P4 Oio, contains the same triangular arrangement of phosphorus atoms as in P4, but an oxygen atom is inserted into each P—P bond. An additional terminal O atom is double-bonded to each P atom. 

The partial oxidation of propylene occurs via a similar mechanism, although the surface structure of the bismuth-molybdenum oxide is much more complicated than in Fig. 9.17. As Fig. 9.18 shows, crystallographically different oxygen atoms play different roles. Bridging O atoms between Bi and Mo are believed to be responsible for C-H activation and H abstraction from the methyl group, after which the propylene adsorbs in the form of an allyl group (H2C=CH-CH2). This is most likely the rate-determining step of the mechanism. Terminal O atoms bound to Mo are considered to be those that insert in the hydrocarbon. Sites located on bismuth activate and dissociate the O2 which fills the vacancies left in the coordination of molybdenum after acrolein desorption. 

Figure 5. Cartoon models of the reaction of methanol with oxygen on Cu(llO). 1 A methanol molecule arrives from the gas phase onto the surface with islands of p(2xl) CuO (the open circles represent oxygen, cross-hatched are Cu). 2,3 Methanol diffuses on the surface in a weakly bound molecular state and reacts with a terminal oxygen atom, which deprotonates the molecule in 4 to form a terminal hydroxy group and a methoxy group. Another molecule can react with this to produce water, which desorbs (5-7). Panel 8 shows decomposition of the methoxy to produce a hydrogen atom (small filled circle) and formaldehyde (large filled circle), which desorbs in panel 9. The active site lost in panel 6 is proposed to be regenerated by the diffusion of the terminal Cu atom away from the island in panel 7.

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