Name: frost circle for pi orbital energies
Uploaded: 2023-04-30T10:31:15.000Z
Duration: 1 min 8 s
Channel: JoVE

Don çemberi veya yazılı çokgen yöntemi, düzlemsel, monosiklik ve konjuge sistemlerin π moleküler orbitallerinin sayısını ve bağıl enerjilerini belirlemek için Hückel kuralına dayanan grafiksel bir yöntemdir.
Bir Frost çemberi, döngüsel bileşiği temsil eden bir çokgenin, köşelerinden biri aşağıyı gösterecek şekilde bir dairenin içine yazılmasıyla çizilir.
Dairenin çokgene değdiği kesişimler, π moleküler orbitallerin sayısını ve bağıl enerjilerini temsil eden kısa yatay çizgilerle işaretlenir.
Daha sonra, çokgeni ikiye bölerek dairenin merkezinden kesikli bir yatay çizgi çizilir. Bu çizgi, katılan p orbitallerinin enerjisini temsil eder.
Bu çizginin altındaki enerjilere sahip tüm moleküler orbitaller bağdır, çizginin üzerindekiler antibonddur ve çizgidekiler bağ yapmayan moleküler orbitallerdir.
Son olarak, π elektronlar, Hund kuralına ve Pauli'nin dışlama ilkesine göre enerji seviyelerine eklenir.

hückel'in π mo'ların kural diyagramı: frost Çemberi

H&uuml;ckel's Rule Diagram of &pi; MOs: Frost Circle

Frost çemberi veya yazılı çokgen yöntemi, düzlemsel, tamamen konjuge ve monosiklik bileşikler için π moleküler yörüngelerin (MO'lar) bağıl enerjilerini belirlemek için kullanılan grafiksel bir yöntemdir. Bu yöntem ilk olarak 1953 yılında A. A. Frost ve Boris Musulin tarafından tarif edilmiştir.

Bir Frost çemberi, köşelerinden biri aşağıya bakacak şekilde, kenar sayısı verilen siklik sistemin karbon sayısına eşit olan bir çokgen çizilerek oluşturulur. Daha sonra, çokgenin tüm köşeleri çembere değecek şekilde çokgeni çevreleyen bir çember çizilir. Çemberin çokgene dokunduğu noktalar, π moleküler yörüngelerin enerji seviyelerini temsil eden kısa yatay çizgilerle işaretlenmiştir.

<img alt="Figure1" src="/files/ftp_upload/12454/12454_PT-Figure_1.png" style="text-align: center; height: 250px;">

Daha sonra çemberin ortasından çokgeni ikiye bölen kesikli yatay bir çizgi çizilir. Bu çizginin altındaki enerji seviyeleri, bağ moleküler yörüngelerini temsil eder ve bu çizginin üzerindeki enerji seviyeleri, bağönler moleküler yörüngelerini temsil eder. Çizgideki enerji seviyeleri, moleküler yörüngelerin oluşturulduğu p yörüngelerine eşit enerji ile bağlanmayan moleküler yörüngeleri temsil eder.

Son olarak π elektronları en düşükten başlayarak yukarıya doğru enerji seviyelerine eklenir. Dejenere yörüngeler önce tek bir elektronla doldurulur ve ardından Pauli'nin dışlama ilkesi ve Hund'un kurallarına uygun olarak varsa başka bir elektronla eşleştirilir.

Hückel'in π MO'ların Kural Diyagramı: Frost Çemberi

Don çemberi veya yazılı çokgen yöntemi, π moleküler orbitallerin (MO'lar) bağıl enerjilerini belirlemek için grafiksel bir yöntemdir.

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frost circle for pi orbital energies

The Frost circle is a graphical method for showing the relative energies of pi molecular orbitals in planar, fully conjugated, monocyclic compounds. It is also called the inscribed polygon method. A. A. Frost and Boris Musulin first described this method in 1953.

To build a Frost circle, draw a polygon with the same number of edges as the number of carbons in the cyclic system. Place one vertex pointing downward. Then draw a circle around the polygon so that every vertex touches the circle. Mark the touch points with short horizontal lines. These lines show the energy levels of the pi molecular orbitals.

Next, draw a dashed horizontal line through the center of the circle. This line divides the energy levels into bonding, non-bonding, and antibonding orbitals. Levels below the line are bonding molecular orbitals. Levels above the line are antibonding molecular orbitals. The levels on the line are non-bonding molecular orbitals, and they have the same energy as the p orbitals that form them.

Finally, place the pi electrons into the energy levels from lowest to highest. If two orbitals have the same energy, they are degenerate orbitals. Fill each degenerate orbital with one electron first, then pair the electrons if more are available. This follows Pauli’s exclusion principle and Hund’s rules.

Frost Circle for Pi Orbital Energies

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h&uuml;ckel's rule diagram of &pi; mos: frost circle

The Frost circle is a graphical method for showing the relative energies of pi molecular orbitals in planar, fully conjugated, monocyclic compounds. It is also called the inscribed polygon method. A. A. Frost and Boris Musulin first described this method in 1953. To build a Frost circle, draw a polygon with the same number of edges as the number of carbons in the cyclic system. Place one vertex pointing downward. Then draw a circle around the polygon so that every vertex touches the circle.

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Learn how the Frost circle maps pi molecular orbital energies in planar conjugated rings, from drawing the polygon to filling bonding, non-bonding, and antibonding levels.

Frost Circle for Pi Orbital Energies | JoVE K12

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Frost Circle for Pi Orbital Energies

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