Some energetic and bonding considerations

Some energetic and bonding considerations significantly stronger than the Cl-Cl bond (242kJmol ) 

The first point is illustrated by considering that although the combustions of CH4 and S1H4 are both thermodynamically favourable, S1H4 is spontaneously inflammable in air, whereas CH4 explodes in air only when a spark provides the energy to overcome the activation barrier. In respect of the second point, consider reaction 14.5. 

Inspection of Table 14.2 shows that (C—H) i (C—Cl), but the fact that the H—Cl bond (431kJmoP ) is 

Catenation is the tendency for covalent bond formation between atoms of a given element, e.g. C—C bonds in hydrocarbons or S—S bonds in polysulfides. 

The particular strength of the C—C bond contributes towards the fact that catenation in carbon compounds is common. However, it must be stressed that kinetic as well as thermodynamic factors may be involved, and any detailed discussion of kinetic factors is subject to complications  

The particular strength of the C—C bond contributes towards the fact that catenation in carbon compounds is 

Hn a second structurally characterized polymorph, the orientations of the mesityl groups differ, see R. Okazaki and R. West (1996) Advances in Organometallic Chemistry, vol. 39, p. 231. 

The possible role of (p-fi )7r-bonding for Si and the later elements in group 14 has been a controversial issue (see Section 5.7) and we return to this in Section 14.6. On the other hand, (p-p)7r-bonding leading to double and triple homonuclear bonds, which is so common in carbon chemistry, is relatively unimportant later in the group. A similar situation is observed in groups 15 and 16. The 

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It is difficult to see how the presence of two double bonds in each polymer molecule (reported by Eley and Richards for the polymerisation of 2-ethyl hexyl vinyl ether) can be explained without assuming that the chain is started by an unsaturated entity, and that the second double bond is formed in the termination process. Since the chain growth is almost certainly a carbonium ion process the initiating entity must be a positive ion of some sort. We assume therefore that the ether is split into two ions under the influence of the catalyst. This may obviously occur in two different ways, but energetic considerations can show which of these will in fact take place. 

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