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Effective Control of the Electron‐donating Ability of Phosphines by using Phosphazenyl and Phosphoniumylidyl Substituents
Author(s) -
Werra Janina A.,
Wünsche Marius A.,
Rathmann Patrick,
Mehlmann Paul,
Löwe Pawel,
Dielmann Fabian
Publication year - 2020
Publication title -
zeitschrift für anorganische und allgemeine chemie
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.354
H-Index - 66
eISSN - 1521-3749
pISSN - 0044-2313
DOI - 10.1002/zaac.202000028
Subject(s) - steric effects , phosphine , substituent , chemistry , protonation , phosphonium , isopropyl , electronic effect , carbon atom , medicinal chemistry , crystallography , stereochemistry , organic chemistry , alkyl , ion , catalysis
Phosphoniumylidyl and phosphazenyl groups are effective substituents to increase the electron‐donating ability of tertiary phosphines. However, the influence of structural variations among those substituents on the electronic properties of the phosphines is little explored. Herein, we show that protonation of the ylidic carbon atom of phosphoniumylidyl phosphines increases the Tolman electronic parameter (TEP) by ΔTEP = 16.0–18.8 cm –1 . Furthermore, phosphazenyl phosphines were synthesized with isopropyl groups (NP{ i Pr} 3 ) and tetramethylguanidino groups (NP{tmg} 3 ) at the phosphonium center. Determination of their TEP values reveals a remarkable low substituent parameter of χ = –18.5 cm –1 for the NP(tmg) 3 group. In addition, we prepared the corresponding gold(I) complexes and determined their solid‐state structures using single‐crystal X‐ray diffraction studies to analyze the steric profile of the new phosphine ligands.