Orbital hybridization allenes

What kind of hybridization must the central carbon have Sketch the bonding it orbitals in allene. What shape do you predict for allene ... 

Element Pauling 4 Sanderson X Allred- Rochow Xttv1 Allen X p Orbital hybrid Pauling scale Volts b Volfs/ electron... 

Element Pauling Sandersan x% Allred-Rachow v d Allen p Orbital hybrid Pauling Volts b Volts/ electron... 

The hybridization concept indicates some additional aspects of molecular stmcture. The tetrahedral, trigonal, and digonal natures of sp, sp, and sp carbon atoms provide an approximation of bond angles. The idea that tt bonds are formed by the overlap of p orbitals puts some geometrical constraints on structure. Ethene, for example, is planar to maximize p-orbital overlap. Allene, on the other hand, must have the terminal CH2 groups rotated by 90° to accommodate two tt bonds at the central sp carbon. 

State the orbital hybridization of each carbon in allene. 

Allerie, P12C — C = CH2> is somewhat unusual in that it has two adjacent double bonds. Draw a picture showing the orbitals involved in the u and -n- bonds of allene. Is the central carbon atom sp2- or sp-hybridized What about the hybridization of the terminal carbons What shape do you predict for allene ... 

Reed and Allen, using their bond polarity index, have assigned values of 0.000, 0.027, and 0.050, respectively (compared to H —0.032 and F 0.189) [108]. Without attempting to be too quantitative, convenient values of the core energies of hybrid atomic orbitals, in units, recognizing that changes in coordination number also occur, are approximately... 

Describe the hybridization of the carbon atoms in allene, H2C=C=CH2, and make a rough sketch of the molecule showing its hybrid orbitals. 

Because the central carbon atom in allene has two charge clouds (two double bonds), it has a linear geometry and is sp-hybridized. Because the two terminal carbon atoms have three charge clouds each (one double bond and two C-H bonds), they have trigonal planar geometry and are sp2-hybridized. The central carbon uses its sp orbitals to form two cr bonds at 180° angles and uses its two unhybridized p orbitals to form... 

Allene has two adjacent carbon-carbon double bonds. Its geometry is not planar like a normal alkene. The central carbon is sp hybridized and has linear geometry. The two p orbitals that it uses for the two double bonds are perpendicular, so the planes of the two double bonds are perpendicular. The two hydrogens on one end of allene lie in a plane perpendicular to the two hydrogens on the other end. 

In allene, the central carbon atom is sp hybridized and linear (Section 2-4), and the two outer carbon atoms are sp2 hybridized and trigonal. We might imagine that the whole molecule lies in a plane, but this is not correct. The central sp hybrid carbon atom must use different p orbitals to form the pi bonds with the two outer carbon atoms. The two unhybridized p orbitals on the sp hybrid carbon atom are perpendicular, so the two pi bonds must also be perpendicular. Figure 5-19 shows the bonding and three-dimensional structure of allene. Allene itself is achiral. If you make a model of its mirror image, you will find it identical with the original molecule. If we add some substituents to allene, however, the molecule may be chiral. 

Allene (see Problem 1.46) is related structurally to carbon dio.xide, CO2. Draw a picture showing the orbitals involved in the [Pg.33]

Element Pauling Sanderson Af5 Allred- Rochow Allen spec Orbital or hybrid a b... 

Note that the procedure described here can be extended without difficulty to atoms P which contribute severed orbitals and several p electrons of different symmetries carbon atoms in the sp hybridization state of acetylene and allene-type compounds 28>, heteroatoms with one n electron and a lone pair, like oxygen in the carbonyl group or nitrogen in pyridine 20,21). 

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