Octahedral wedge

TABLE 8.3 Ligand (Crystal) Field Contributions to the Activation Energy for Exchange Reactions of Transition Metal Ions Assuming Square Pyramid and Octahedral Wedge Transition States to Represent Dissociative and Associative Activation, Respectively"... 

For an octahedral wedge transition state, except as indicated. cFor a square pyramidal transition state. 

Such calculations are shown in Table 3.IS for the square pyramid and octahedral wedge intermediates. If one disregards differences in Dq for different metal ions, these calculations predict the order of reactivity for a square pyramid transition state as (d, (d, (d d ) > (d , d )... 

Figure 2.4.2. Structure of the heptacoordinated octahedral wedge . X is the leaving ligand and Y is the entering ligand.

Wedged octahedral structure for 1 1 adduct of tristdi-pivalomethanato)-europium(III) and 3,3-dimethyl-thietane- 1-oxide... 

The first example represents a tetrahedral arrangement, because the sofid defined by the four chlorine atoms at its apices is a tetrahedron. The second is octahedral, and the third represents two edge-fused tetrahedra. The wedge bonds are pointing in front of or behind the plane of the paper the thin lines designate bonds in the plane of the paper. 

With [Eu(dpm)3], 3,3-dimethylthietane 1 -oxide and DMSO gave 1 1 adducts, which had near perfect wedged octahedral structures, the Lewis bases occupying one of four equivalent positions of lowest symmetry. The species [M(dpm)3] (M = La, Pr, Eu, Er, Ho, or Lu) were monomeric in dry CCI4, and 1 1 adducts were formed with pyridine, borneol, and neopentanol. However, lanthanide shift reagents (L) could react with substrates (S) by a two-step mechanism, viz. 

Figure 22.11 Optical isomerism in an octahedral complex ion. A, Structrre I and its mirror image, structure II, are optical isomers of C(s-[Co(en)2Cl2] . Rotating structure I gives structure III, which is not the same as structure II. (The curved wedges represent the bidentate...

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