What is the lowest energy alternative resonance structure for this compound:
CH3-CH-N<triple bond>N
There is a negative charge on CH and a positive charge on the central N
To determine the lowest energy alternative resonance structure for the given compound (CH3-CH-N≡N) with a negative charge on CH and a positive charge on the central N, we need to examine the electron distribution in the molecule and identify any possible resonance structures.
Here's how you can approach it:
1. Analyze the electron distribution: The molecule consists of a carbon atom (C) bonded to two hydrogen atoms (H), which is connected to a nitrogen atom (N) via a triple bond (≡) and another nitrogen atom (N). The CH3 group is negatively charged, and the central N atom is positively charged. Each bond consists of two electrons, and each lone pair contributes two electrons.
2. Identify possible resonance structures: To find the alternative resonance structure(s), you need to distribute the charges and electrons differently without breaking any bonds. Start by moving an electron from the multiple bond (≡) to a neighboring atom (either C or N). You can also redraw double bonds or rearrange lone pairs. Keep in mind that the overall charge must remain the same in each resonance structure.
3. Evaluate the stability of the resonance structures: The lowest energy resonance structure will be the one that has the fewest charges, maximizes electron density, and adheres to the octet rule as much as possible.
For the given compound (CH3-CH-N≡N) with a negative charge on CH and a positive charge on the central N, the possible resonance structures could be as follows:
CH3 ← CH = N≡N
or
CH3 → C = N≡N
In the first resonance structure, the negative charge is located on the CH3 group, while the second structure places the positive charge on the carbon atom.
4. Determine the lowest energy resonance structure: To identify the lowest energy resonance structure, compare the stability of the two structures. Generally, a negative charge on a more electronegative atom is more stabilizing, so the first resonance structure (CH3 ⬅ CH = N≡N) is likely to be the lowest energy alternative resonance structure for the given compound.
Remember, this is a general guide, and it's always essential to consider electronegativity, formal charges, and electron distribution while evaluating resonance structures.