| Autor: |
Burgoyne MM; Department of Chemistry, University of New Brunswick, Fredericton, New Brunswick E3B 5A3, Canada. cadyker@unb.ca., MacDougall TM; Department of Chemistry, University of New Brunswick, Fredericton, New Brunswick E3B 5A3, Canada. cadyker@unb.ca., Haines ZN; Department of Chemistry, University of New Brunswick, Fredericton, New Brunswick E3B 5A3, Canada. cadyker@unb.ca., Conrad JW; Department of Chemistry, University of New Brunswick, Fredericton, New Brunswick E3B 5A3, Canada. cadyker@unb.ca., Calhoun LA; Department of Chemistry, University of New Brunswick, Fredericton, New Brunswick E3B 5A3, Canada. cadyker@unb.ca., Decken A; Department of Chemistry, University of New Brunswick, Fredericton, New Brunswick E3B 5A3, Canada. cadyker@unb.ca., Dyker CA; Department of Chemistry, University of New Brunswick, Fredericton, New Brunswick E3B 5A3, Canada. cadyker@unb.ca. |
| Abstrakt: |
The π-electron donor strength of a triphenylphosphonium ylidyl group (Ph 3 P[double bond, length as m-dash]CH-) was explored through its substitution onto a bispyridinylidene (BPY) scaffold. Electrochemical studies revealed that the new triphenylphosphonium ylidyl-substituted BPY is the most reducing di-substituted derivative reported to date (E 1/2 = -1.55 V vs. SCE). By using a previously established correlation between the redox potential of the substituted BPYs and the corresponding substituent, a Hammett constant for the Ph 3 P[double bond, length as m-dash]CH- group was determined (σ p + = -2.33), establishing it as the most donating neutral substituent currently quantified. The BPY is readily oxidized by hexachloroethane to produce the corresponding dicationic bipyridinium salt as a mixture of isomers owing to hindered C ylidyl -C pyridyl bond rotation. In preliminary tests of the BPY as a reductant, dichlorotricyclohexylphosphorane and chlorodiphenylphosphine were reduced to the corresponding phosphine and diphosphine, respectively. |
