Atoms Bearing Certain Functional Groups

Other types of reactions often have functional groups that show a special relationship in a particular reaction. The disconnection 109 =s 110 suggests a relationship between the tertiary amine in 109 and the dienyl azide moieties in 110.99 when 110 was heated in toluene, a [3-i-2]-cycloaddition occurred to give a 

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Disconnect appendages attached to atoms bearing certain functional groups such as OH or C=0. 

Translation of the PtClJ- ion in the x and y directions can be represented by the two vectors shown on the platinum atom (Fig. 3.19). fn contrast to all of the cases we have so far considered, certain operations of the Du group lead to new orientations for both vectors that do not bear a simple +1 or — I relationship to the original positions. For example, under a clockwise C4 operation, the x vector is rotated to the + y direction, and the y vector is rotated to a -x position. The character for this operation is zero. (This arises because the diagonal elements of the matrix for this operation are all zero other elements in the matrix are nonzero but do not contribute to the character.) The S4 and operations lead to a similar muting of tbe x and y functions and also have characters of zero. Because of this mixing, the x and y functions are inseparable within the />4k symmetry group and arc said to transform as a doubly degenerate or two-dimensional representation. 

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