Evaluation of the Stereoelectronic Parameters of Fluorinated Phosphorus(III) Ligands. The Quantitative Analysis of Ligand Effects (QALE)

Document Type

Article - Merrimack Access Only

Publication Title

Organometallics

Publisher

American Chemical Society

Publication Date

6-2001

Abstract/ Summary

Using the QALE model, we determined the QALE stereoelectronic parameters for the following ligands: P(CF3)3 (χd = 33 ± 2, θ = 137 ± 13°, Ear = 0, πp = 11.1 ± 0.6), P(CH2- CH2C6F13)3 (χd = 9 ± 3, θ ) 137 ( 2°, Ear = 0, πp = 2.5 ± 0.4), P[p-(F13C6)C6H4]3 (χd = 23 ± 1, θ = 145°, Ear = 2.7, πp = 0), and P(C6F5)3 (χd ) 34 ± 2, θ = 191 ± 13°, Ear = 4.3 ± 0.5, πp = 0). In addition, we evaluated the parameters for P[Pyr-3,4-(CO2Et)2]3 (Pyr ) pyrrolyl; χd ) 43 ± 2, θ = 145°, Ear ) 3.3, πp = 2 ± 1). Revised parameters for PF3 are also presented: χd = 33 ± 2, θ = 110 ± 24°, Ear = 0, πp = 13.2 ± 0.5. The absence of an indicated error means that these values were assigned initially to the particular parameters in the analyses or that the parameters are statistically indistinguishable from zero. Where a comparison can be made, we find that our calculated values of θ are indistinguishable from those of Tolman; therefore, we suggest the continued use of Tolman’s values. It is observed that the perfluoroalkyl groups are highly π acidifying and that this effect is transmitted through intervening CH2 groups.

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