sp2

Examples of sp2 in the following topics:

• sp2 Hybridization

  • sp2 Hybridization in Ethene and the Formation of a Double Bond
  • In this case, carbon will sp2 hybridize; in sp2 hybridization, the 2s orbital mixes with only two of the three available 2p orbitals, forming a total of three sp hybrid orbitals with one p-orbital remaining.
  • The two carbon atoms form a sigma bond in the molecule by overlapping two sp2 orbitals.
  • The carbon atoms are sp2 hybridized.
  • Recognize the role of sp2 hybridized atoms in sigma and pi bonding.

• Hybridization in Molecules Containing Double and Triple Bonds

  • sp2, sp hybridizations, and pi-bonding can be used to describe the chemical bonding in molecules with double and triple bonds.
  • For this molecule, carbon will sp2 hybridize.
  • In sp2 hybridization, the 2s orbital mixes with only two of the three available 2p orbitals, forming a total of 3 sp2 orbitals with one p-orbital remaining.
  • In ethylene (ethene), the two carbon atoms form a sigma bond by overlapping two sp2 orbitals; each carbon atom forms two covalent bonds with hydrogen by s–sp2 overlapping all with 120° angles.
  • In ethene, carbon sp2 hybridizes, because one π (pi) bond is required for the double bond between the carbons, and only three σ bonds form per carbon atom.

• Group Frequencies

  • Since most organic compounds have C-H bonds, a useful rule is that absorption in the 2850 to 3000 cm-1 is due to sp3 C-H stretching; whereas, absorption above 3000 cm-1 is from sp2 C-H stretching or sp2 C-H stretching if it is near 3300 cm-1.

• Stereogenic Nitrogen

  • It rapidly inverts its configuration (equilibrium arrows) by passing through a planar, sp2-hybridized transition state, leading to a mixture of interconverting R and S configurations.

• Configurational Stereoisomers of Alkenes

  • The carbon-carbon double bond is formed between two sp2 hybridized carbons, and consists of two occupied molecular orbitals, a sigma orbital and a pi orbital.

• Other Aromatic Compounds

  • A planar (or near planar) cycle of sp2 hybridized atoms, the p-orbitals of which are oriented parallel to each other.
  • Cyclooctatetraene fails both requirements, although it has a ring of sp2 hybridized atoms.
  • It is planar, bond angles=120º, all carbon atoms in the ring are sp2 hybridized, and the pi-orbitals are occupied by 6 electrons.
  • By hybridizing this heteroatom to a sp2 state, a p-orbital occupied by a pair of electrons and oriented parallel to the carbon p-orbitals is created.
  • The sp2 hybridized ring atoms are connected by brown bonds, the π-electron pairs and bonds that constitute the aromatic ring are colored blue.

• Allotropes of Carbon

  • It is an allotrope of carbon whose structure is a single planar sheet of sp2 bonded carbon atoms that are densely packed in a honeycomb crystal lattice.
  • The properties of amorphous carbon depend on the ratio of sp2 to sp3 hybridized bonds present in the material.
  • Graphite consists purely of sp2 hybridized bonds, whereas diamond consists purely of sp3 hybridized bonds.

• Properties of Alkenes

  • The carbon atoms in the double bond are sp2 hybridized, forming a planar structure.

• Nucleophilic Addition Reactions & Reduction

  • Isolated carbon double-bonds are not reduced by sodium in liquid ammonia, confirming the electronegativity difference between sp and sp2 hybridized carbons.

• Substitution

  • Such addition-elimination processes generally occur at sp2 or sp hybridized carbon atoms, in contrast to SN1 and SN2 reactions.