Trigonal planar arrangement defined

The configuration of most R2P-NR2 compounds is represented by F2P-NMe2, which features a short P-N distance (162.8 pm) and trigonal planar arrangement (sp2 hybridization) at the N atom. The plane defined by the C2N unit bisects the F-P-F angle. This configuration minimizes steric repulsion between the substituents on P and N and also orients the lone pairs on the P and N atoms at a dihedral angle of about 90°, as shown in Fig. 15.5.1(a). 

To ensure that the arrangement of four atoms in a trigonal planar environment (e.g., a sp -hybridized carbon atom) remains essentially planar, a quadratic term like V(0) = (fe/2) is used to achieve the desired geometry. By calculating the angle 9 between a bond from the central atom and the plane defined by the central... 

The trigonal planar zinc phenoxide complex [K(THF)6][Zn(0-2,6-tBu2C6H3)3] is formed by the reaction of a zinc amide complex, via a bis phenoxide, which is then further reacted with potassium phenoxide. TheoX-ray structure shows a nearly perfect planar arrangement of the three ligands with zinc only 0.04 A out of the least squares plane defined by the three oxygen atoms.15 Unlike the bisphenoxide complexes of zinc with coordinated THF molecules, these complexes are not cataly-tically active in the copolymerization of epoxides with C02. The bisphenoxide complex has also been structurally characterized and shown to be an effective polymerization catalyst. 43... 

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