Single bond, electronic structure length

Single bond, electronic structure of, 14 length of, 14 see also Alkane strength of, 14 Skeletal structure, 23... 

Examine the geometry of porphin. Is the molecule planar Does the molecule incorporate explicit single and double bonds (as in the structure above) or bonds of intermediate length How many % electrons are involved in porphin s central ring Is poiphin aromatic Elaborate. 

When there is electronic resonance, the bond lengths, bond angles, and nuclear positions are intermediate between those corresponding to the individual resonance structures, as found in the crystal structure of the tin dimer.32 This type of bond, that is, a single bond plus a resonating unshared electron pair, was subsequently found to occur on the 100 surfaces of silicon.33... 

There are many other molecules in which some of the electrons are less localized than is implied by a single Lewis structure and can therefore be represented by two or more resonance structures. For example, the three bonds in the carbonate ion all have the same length of 131 pm, which is intermediate between that of the C—O single bond in methanol (143 pm) and that of the C=0 double bond in methanal (acetaldehyde) (121 pm). So the carbonate ion can be conveniently represented by the following three resonance structures ... 

If one rotates about a C-C single bond in a compound of type X-C-C-Y, at each step of this torsional motion there are electron redistributions, and the bond lengths and angles will change. This phenomenon is the basis of the local nature of molecular structure. Several examples are illustrated in Figs. 7.6 and 7.7. 

These dimeric complexes involve, in their neutral state, two metal atoms in the (III) oxidation state. In the vanadium complexes such as [CpV(bdt)]2 and [CpV(tft)]2, the V—V bond length, 2.54 A in [CpV(bdt)]2, are shorter than observed in model complexes with a single V—V bond, indicating a partial double-bond character, also confirmed by a measured magnetic moment of 0.6 fiB in [CpV(tfd)]2, lower than expected if the two remaining unpaired electrons contribute to the magnetic susceptibility [20, 49]. This class of complexes most probably deserves deeper attention in order to understand their exact electronic structure. 

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