Syntheses, Structures, Bonding and Photoelectron Spectra of “Push‐Pull”‐Substituted P‐[2,6‐Bis(trifluoromethyl)phenyl]‐σ²λ³‐iminophosphanes

Abstract

Abstractσ2λ3‐“Push‐pull” iminophosphanes Arf−P=N−R, bearing an electron‐acceptor substituent at phosphorus [Arf = 2,6‐bis(trifluoromethyl)phenyl] and a donor group at nitrogen (R = tBu, NMe2), have been synthesized and characterized by NMR spectroscopy and X‐ray analysis. Density functional calculations [B3LYP/6‐311G(d,p)] have been carried out on different iminophosphanes: HP=NH (1), ArfP=NH (2), ArfP=NSiMe3 (3), ArfP=NtBu (4), HP=NNMe2 (5) and ArfP=NNMe2 (6) in order to determine the electronic effect of the Arf substituent and the influence of the donor group R on the stability of the monomeric species. A comparison of the theoretical results and UV photoelectron spectroscopy data for the iminophosphanes 4 and 6 is presented. Theoretical and experimental data suggest that for all iminophosphanes under investigation the π‐system of the Arf group is almost orthogonal to the πP=N system, preventing any stabilizing interaction between the πP=N and the π*b1(aryl) orbitals previously observed for the ArfPH− anion. Here, the Arf substituent effect is mainly steric. (© Wiley‐VCH Verlag GmbH & Co. KGaA, 69451 Weinheim, Germany, 2004)

A fluoroaryl substituent with spectator function: Reactivity and structures of cyclic and acyclic HF4C6-substituted phosphanes

“…Further attempts to induce HCl elimination of 10 with Wannagat's base or LDA did not give any satisfactory results. Reaction of 10 with DBU gave so far unidentified products, but formation of the iminophosphane or the corresponding 2 + 2 cycloaddition product can be excluded by comparison of 31 P NMR shifts with literature data [26].…”

2,3,5,6‐Tetrafluoro‐p‐phenylenebis(phosphanes) – Preparation and Structure of an Electron‐Poor P–RF–P Linker

“…[7] Until now only little is known about electron-deficient bis(phosphaalkenes), [8][9][10] although many electron-rich low-coordinated phosphanes have been reported in the last decades. [11][12][13] A special focus of experimental and theoretical work was set on push-pull-substituted low-coordinated phosphanes, especially iminophosphanes, [14,15] diphosphenes, [16,17] and phosphaalkenes. [9] Recently, the twist angle of diphosphenes was studied theoretically, but a detailed explanation highlighting the influence of the electron-accepting groups remains still elusive.…”

Phosphines and Related Tervalent Phosphorus Systems

“…The data suggest that in these molecules, the aryl group at phosphorus is almost orthogonal to the p(P¼N) system, and hence its substituent effect is mainly steric. 732 Conjugation effects in less sterically crowded systems have also been considered by theoretical methods. 733 Evidence has been provided of a reversible iminophosphene-diazadiphosphetidine, monomer-dimer equilibrium involving the iminophosphene (254).…”