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Cyclopropane is a highly strained molecule with bond angle of $60^\circ$. The normal tetrahedral bond angle is $\pu{109^\circ{28}'}$, so we'd expect a ring strain of $49.28^\circ$!

For a cyclopropane C atom, the four hybrid orbitals are not equivalent. The two orbitals directed to the outside bonds have more $\ce{s}$- character than a normal $\ce{sp^3}$ orbital, while the involved in ring bonding have less, because the more $\ce{p}$ like they are, the more they resemble the ordinary $\ce{p}$ orbitals whose ordinary bond angle is $90^\circ$. Since the angle strain is a measure of the difference between the preffered angle and the real angle of $60^\circ$, this additional $\ce{p}$ character relieves the strain. The external bonds have $\sim 33\%$ $\ce{s}$ character, so they are $\sim \ce{sp^2}$ orbitals, while the internal orbitals have $\sim 17\% \ce{~s}$ character so they are $\sim \ce{sp^5}$ orbitals. Thus, each C-C bond is formed by $\ce{sp^5-sp^5}$ verlap.

The bonds in cyclopropane are called bent bonds and they are intermediate in character between $\sigma$ and $\pi$.

Now, coming to the stability of cyclopropyl methyl carbocation, it is symmetrically stabilized by both $\ce{C-C \sigma}$ (2-3 and 2-4) bonds. You may call it bent bond resonance with the vacant $\ce{p}$ orbital of the carbocation.

It is worth mentioning that cyclopropyl group stabilizes an adjacent postive charge even better than a phenyl group.

Source: March's Advanced Organic Chemistry

Cyclopropane is a highly strained molecule with a bond angle of $60^\circ$. The normal tetrahedral bond angle is $\pu{109^\circ{28}'}$, so we'd expect a ring strain of $49.28^\circ$!

For a cyclopropane C atom, the four hybrid orbitals are not equivalent. The two orbitals directed to the outside bonds have more $\ce{s}$- character than a normal $\ce{sp^3}$ orbital, while the involved in ring bonding have less, because the more $\ce{p}$ like they are, the more they resemble the ordinary $\ce{p}$ orbitals whose ordinary bond angle is $90^\circ$. Since the angle strain is a measure of the difference between the preferred angle and the real angle of $60^\circ$, this additional $\ce{p}$ character relieves the strain. The external bonds have $\sim 33\%$ $\ce{s}$ character, so they are $\sim \ce{sp^2}$ orbitals, while the internal orbitals have $\sim 17\% \ce{~s}$ character so they are $\sim \ce{sp^5}$ orbitals. Thus, each C-C bond is formed by $\ce{sp^5-sp^5}$ overlap.

The bonds in cyclopropane are called bent bonds and they are intermediate in character between $\sigma$ and $\pi$.

Now, coming to the stability of cyclopropyl methyl carbocation, it is symmetrically stabilized by both $\ce{C-C \sigma}$ (2-3 and 2-4) bonds. You may call it bent bond resonance with the vacant $\ce{p}$ orbital of the carbocation.

It is worth mentioning that cyclopropyl group stabilizes an adjacent postive charge even better than a phenyl group.

Source: March's Advanced Organic Chemistry

Cyclopropane is a highly strained molecule with bond angle of $60^\circ$. The normal tetrahedral bond angle is $\pu{109^\circ{28}'}$, so we'd expect a ring strain of $49.28^\circ$!

For a cyclopropane C atom, the four hybrid orbitals are not equivalent. The two orbitals directed to the outside bonds have more $\ce{s}$- character than a normal $\ce{sp^3}$ orbital, while the involved in ring bonding have less, because the more $\ce{p}$ like they are, the more they resemble the ordinary $\ce{p}$ orbitals whose ordinary bond angle is $90^\circ$. Since the angle strain is a measure of the difference between the preffered angle and the real angle of $60^\circ$, this additional $\ce{p}$ character relieves the strain. The external bonds have $\sim 33\%$ $\ce{s}$ character, so they are $\sim \ce{sp^2}$ orbitals, while the internal orbitals have $\sim 17\% \ce{~s}$ character so they are $\sim \ce{sp^5}$ orbitals. Thus, each C-C bond is formed by $\ce{sp^5-sp^5}$ verlap.

The bonds in cyclopropane are called bent bonds and they are intermediate in character between $\sigma$ and $\pi$.

Now, coming to the stability of cyclopropyl methyl carbocation, it is symmetrically stabilized by both $\ce{C-C \sigma}$ (2-3 and 2-4) bonds. You may call it bent bond resonance with the vacant $\ce{p}$ orbital of the carbocation.

[![enter image description here][1]][1]

It is worth mentioning that cyclopropyl group stabilizes an adjacent postive charge even better than a phenyl group.

Source: March's Advanced Organic Chemistry [1]: https://i.sstatic.net/eqbIs.png

Cyclopropane is a highly strained molecule with bond angle of $60^\circ$. The normal tetrahedral bond angle is $\pu{109^\circ{28}'}$, so we'd expect a ring strain of $49.28^\circ$!

For a cyclopropane C atom, the four hybrid orbitals are not equivalent. The two orbitals directed to the outside bonds have more $\ce{s}$- character than a normal $\ce{sp^3}$ orbital, while the involved in ring bonding have less, because the more $\ce{p}$ like they are, the more they resemble the ordinary $\ce{p}$ orbitals whose ordinary bond angle is $90^\circ$. Since the angle strain is a measure of the difference between the preffered angle and the real angle of $60^\circ$, this additional $\ce{p}$ character relieves the strain. The external bonds have $\sim 33\%$ $\ce{s}$ character, so they are $\sim \ce{sp^2}$ orbitals, while the internal orbitals have $\sim 17\% \ce{~s}$ character so they are $\sim \ce{sp^5}$ orbitals. Thus, each C-C bond is formed by $\ce{sp^5-sp^5}$ verlap.

The bonds in cyclopropane are called bent bonds and they are intermediate in character between $\sigma$ and $\pi$.

Now, coming to the stability of cyclopropyl methyl carbocation, it is symmetrically stabilized by both $\ce{C-C \sigma}$ (2-3 and 2-4) bonds. You may call it bent bond resonance with the vacant $\ce{p}$ orbital of the carbocation.

It is worth mentioning that cyclopropyl group stabilizes an adjacent postive charge even better than a phenyl group.

Source: March's Advanced Organic Chemistry

Cyclopropane is a highly strained molecule with bond angle of $60^\circ$. The normal tetrahedral bond angle is $\pu{109^\circ{28}'}$, so we'd expect a ring strain of $49.28^\circ$!

For a cyclopropane C atom, the four hybrid orbitals are not equivalent. The two orbitals directed to the outside bonds have more $\ce{s}$- character than a normal $\ce{sp^3}$ orbital, while the involved in ring bonding have less, because the more $\ce{p}$ like they are, the more they resemble the ordinary $\ce{p}$ orbitals whose ordinary bond angle is $90^\circ$. Since the angle strain is a measure of the difference between the preffered angle and the real angle of $60^\circ$, this additional $\ce{p}$ character relieves the strain. The external bonds have $\sim 33\%$ $\ce{s}$ character, so they are $\sim \ce{sp^2}$ orbitals, while the internal orbitals have $\sim 17\% \ce{~s}$ character so they are $\sim \ce{sp^5}$ orbitals. Thus, each C-C bond is formed by $\ce{sp^5-sp^5}$ verlap.

The bonds in cyclopropane are called bent bonds and they are intermediate in character between $\sigma$ and $\pi$.

Now, coming to the stability of cyclopropyl methyl carbocation, it is symmetrically stabilized by both $\ce{C-C \sigma}$ (2-3 and 2-4) bonds. You may call it bent bond resonance with the vacant $\ce{p}$ orbital of the carbocation.

[![enter image description here][1]][1]

It is worth mentioning that cyclopropyl group stabilizes an adjacent postive charge even better than a phenyl group.

Reference: March's Advanced Organic Chemistry [1]: https://i.sstatic.net/eqbIs.png

Cyclopropane is a highly strained molecule with bond angle of $60^\circ$. The normal tetrahedral bond angle is $\pu{109^\circ{28}'}$, so we'd expect a ring strain of $49.28^\circ$!

For a cyclopropane C atom, the four hybrid orbitals are not equivalent. The two orbitals directed to the outside bonds have more $\ce{s}$- character than a normal $\ce{sp^3}$ orbital, while the involved in ring bonding have less, because the more $\ce{p}$ like they are, the more they resemble the ordinary $\ce{p}$ orbitals whose ordinary bond angle is $90^\circ$. Since the angle strain is a measure of the difference between the preffered angle and the real angle of $60^\circ$, this additional $\ce{p}$ character relieves the strain. The external bonds have $\sim 33\%$ $\ce{s}$ character, so they are $\sim \ce{sp^2}$ orbitals, while the internal orbitals have $\sim 17\% \ce{~s}$ character so they are $\sim \ce{sp^5}$ orbitals. Thus, each C-C bond is formed by $\ce{sp^5-sp^5}$ verlap.

The bonds in cyclopropane are called bent bonds and they are intermediate in character between $\sigma$ and $\pi$.

Now, coming to the stability of cyclopropyl methyl carbocation, it is symmetrically stabilized by both $\ce{C-C \sigma}$ (2-3 and 2-4) bonds. You may call it bent bond resonance with the vacant $\ce{p}$ orbital of the carbocation.

[![enter image description here][1]][1]

It is worth mentioning that cyclopropyl group stabilizes an adjacent postive charge even better than a phenyl group.

Source: March's Advanced Organic Chemistry [1]: https://i.sstatic.net/eqbIs.png