Among the resonance structures of SCN-, is it true that the more widely-used structure is considered the "real" structure? Two resonance structures of SCN- are S=C=N and S-C≡N.
When dealing with resonance structures, it is important to understand that they are not actual representations of the molecule, but rather different depictions of its possible electronic configurations. Resonance structures are used to describe the delocalization of electrons within a molecule or ion.
In the case of SCN-, there are two resonance structures: S=C=N and S-C≡N. These structures indicate that the double bond can be found between the sulfur atom and the carbon atom (S=C=N) or the triple bond between the sulfur atom and the nitrogen atom (S-C≡N).
It is not accurate to say that one of these resonance structures is the "real" structure, as that would imply that one is more accurate than the other. In reality, the actual electronic configuration of SCN- is a combination, or hybrid, of these resonance structures. The electrons in the molecule are delocalized, meaning that they are spread out over the entire molecule rather than being confined to a particular bond.
To determine the relative contributions of each resonance structure, we look at the stability of the individual structures. In general, structures with more covalent bonds and fewer formal charges tend to be more stable.
In this case, the S=C=N structure has one double bond and one formal charge, while the S-C≡N structure has one triple bond and no formal charges. By comparing the structures, we can deduce that the S-C≡N structure tends to dominate, as triple bonds are stronger and more stable than double bonds, and the absence of a formal charge contributes to stability.
Therefore, while both resonance structures are important in describing the electronic nature of SCN-, the S-C≡N structure is generally considered to be the more stable and dominant form.