Tetrahedral hybrids

The classification can be illustrated with a few examples. All of the nucleophilic substitutions shown in Scheme 3.4 are of the exo-tet classification. The reacting atom is of sp hybridization (tetrahedral = tet), and the reacting bond, that is, the bond to the leaving grov, is exocyclic to the forming ring ... 

Potential functions based on the sp3-hybrid tetrahedral structure model of water molecules in which two positive and two negative charges are placed at the tetrahedral positions in the molecule have been proposed by Bjerrum 1), Ben-Naim and Stillinger (BNS model) (2), and Stillinger-Rahman (ST2) (3). 

You remember that the aromatic carbons of toluene (Section 5.4) appear far downfield of the methyl carbon. Just as with vinyl and aromatic hydrogens (Sections 6.3 and 6.5), sp2 hybridized vinyl and aromatic carbons are deshielded in comparison to their sp3 hybridized tetrahedral counterparts. For this reason, their signals usually fall in the region of 8 100-165. 

Fig. 17 Multiple hybrid-(tetrahedral) jzation schemes in zinc compounds...

When an sp3 hybridized tetrahedral carbon is attached to four different groups, as in 1 (see below), the molecule cannot be superimposed on its mirror image. This is the same property that a right hand, say, placed in front of a plane mirror possesses. Molecules such as 1 are said to be chiral (or handed), from the Greek word cheir for hand. 

The hybridization of the nitrogen and the triple-bonded carbon are sp, giving linear geometry (C—C—N are linear) and a bond angle around the triple-bonded carbon of 180°. The CH3 carbon is sp hybridized, tetrahedral, with bond angles about 109°... 

A carbon with four bonded atoms is sp3-hybridized, tetrahedral, and has approximately 109° bond angles. The four atomic orbitals on carbon (an s and three p s) combine, through a process called hybridization, to form new orbitals with different geometric orientations. The four new sp3-orbitals are raindrop shaped and are oriented to the corners of a tetrahedron. All bonds to the carbon are sigma bonds. 

The two carbons involved in the triple bond are both sp-hybridized, display linear geometry, and have bond angles of 180°. The other carbon is sp3-hybridized, tetrahedral, and has 109° bond angles. 

Problem 1.29 The carbons involved only in single bonds have four bonded groups and are sp3 hybridized, tetrahedral, and have 109° bond angles. The carbons that have one double bond have three bonded groups and are sp2 hybridized, trigonal, and have 120° bond angles. The carbons involved in triple bonds or two double bonds are sp hybridized, linear, and have 180° bond angles. 

The carbons and nitrogen are sp3-hybridized, tetrahedral, and have bond angles tlhat are approximately 109°. 

The carbons and oxygen each have four space-occupying groups four bonded atoms for each carbon and two bonded atoms and two non-bonding electron pairs for the oxygen. Tlhese atoms are all sp3-hybridized, tetrahedral, and have approximate bond angles of 109°. 

A carbon which is sp hybridized (tetrahedral structure) with four different substituents is called a chiral carbon. If the carbon doesn t have four different substituents or say at least the carbon has two of the same substituents, then it is an achiral carbon. 

O Driscoll, Yonezawa, and Higashimura proposed a mechanism for steric control. In isoprene polymerization the terminal charges are complexed with the metal cations. These cations are close to the active centers through the occupied zr-orbitals of the chain ends and the unoccupied p-orbitals of the lithium ions, hi the transition state the monomers are conqilexed with the cations in die same way. The lithium cations are assumed to be in hybridized tetrahedral sp configurations with four vacant orbitals. The chain ends are presumed to be allylic and the diene monomers are bidentate. During the propagation steps both the monomers and chain ends complex with the same counterions ... 

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