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In Gomberg's dimer, one C-C bond is rather long at 159.7 picometers. It is this bond that reversibly and readily breaks at room temperature in solution: [ 6 ] In the even more congested molecule hexakis(3,5-di- tert -butylphenyl)ethane , the bond dissociation energy to form the stabilized triarylmethyl radical is only 8 kcal/mol.
Unusually long bond lengths do exist. Current record holder for the longest C-C bond with a length of 186.2 pm is 1,8-Bis(5-hydroxydibenzo[a,d]cycloheptatrien-5-yl)naphthalene, [2] one of many molecules within a category of hexaaryl ethanes, which are derivatives based on hexaphenylethane skeleton. Bond is located between carbons C1 and C2 as ...
The bond parameters of ethane have been measured to high precision by microwave spectroscopy and electron diffraction: r C−C = 1.528(3) Å, r C−H = 1.088(5) Å, and ∠CCH = 111.6(5)° by microwave and r C−C = 1.524(3) Å, r C−H = 1.089(5) Å, and ∠CCH = 111.9(5)° by electron diffraction (the numbers in parentheses represents the ...
The textbook explanation for the existence of the energy maximum for an eclipsed conformation in ethane is steric hindrance, but, with a C-C bond length of 154 pm and a Van der Waals radius for hydrogen of 120 pm, the hydrogen atoms in ethane are never in each other's way. The question of whether steric hindrance is responsible for the eclipsed ...
The term bond-dissociation energy is similar to the related notion of bond-dissociation enthalpy (or bond enthalpy), which is sometimes used interchangeably.However, some authors make the distinction that the bond-dissociation energy (D 0) refers to the enthalpy change at 0 K, while the term bond-dissociation enthalpy is used for the enthalpy change at 298 K (unambiguously denoted DH° 298).
An alkane has only C–H and C–C single bonds. The former result from the overlap of an sp 3 orbital of carbon with the 1s orbital of a hydrogen; the latter by the overlap of two sp 3 orbitals on adjacent carbon atoms. The bond lengths amount to 1.09 × 10 −10 m for a C–H bond and 1.54 × 10 −10 m for a C–C bond.
A substituted derivative of hexaphenylethane, hexakis(3,5-di-t-butylphenyl)ethane, has however been prepared. It features a very long central C–C bond at 167 pm (compared to the typical bond length of 154 pm).
The strength of a bond can be estimated by comparing the atomic radii of the atoms that form the bond to the length of bond itself. For example, the atomic radius of boron is estimated at 85 pm, [10] while the length of the B–B bond in B 2 Cl 4 is 175 pm. [11] Dividing the length of this bond by the sum of each boron atom's radius gives a ratio of