Facile Synthesis of Phosphaamidines and Phosphaamidinates using Nitrilium Ions as an Imine Synthon

Abstract

Readily accessible nitrilium triflates are convenient imine building blocks for the expedient synthesis of a novel class of 1,3‐P,N ligands as demonstrated for the reaction with primary phosphanes. This procedure allows variation of all substituents. X‐ray crystal structures are reported for nitrilium ions, phosphaamidines, and three phosphaamidinate complexes. The lithium phosphaamidinate is N coordinated and its reaction with [AuCl(tht)] (tht=tetrahydrothiophene) gives a unique P‐bridged gold trimer, while a P,N‐bidentate complex results from [{RhCl(cod)}2]. The nitrilium ion methodology allows extension of the 1,3‐P,N motive to bis(imino)phosphanes, which are the neutral phosphorus analogues of the valuable β‐diketiminate ligand.

(NHC)Si═C═N–R: A Two-Coordinated Si0-Isocyanide Compound as Si(NHC) Transfer Reagent

“…The 1 H and 13 C NMR spectra of 2 [B­(Ar F ) 4 ] in D 5 -chlorobenzene unequivocally indicate the presence of a configurationally stable, stereogenic Si center in the trigonal pyramidal cations and a fast rotation of the Ar Mes NC and NHC ligands about the respective Si–C bonds at room temperature. The 13 C NMR spectrum of 2 [B­(Ar F ) 4 ] displays a distinctive C carbene signal at δ = 183.7, which appears at higher field than that of SiBr 2 (SIDipp) (δ = 188.7 ppm in D 6 -benzene) and of 1 (δ = 210.8 ppm in D 6 -benzene), and also a distinctive C isocyanide signal at δ = 167.7 ppm, which is upfield shifted of that of free Ar Mes NC (δ C N = 169.6 ppm in D 5 -chlorobenzene) and of 1 (δ C N = 197.9 ppm in D 6 -benzene), indicating the pronounced σ-acceptor character of the fragment [SiBr­(NHC)] + in 2 + the high-field shift being typical for trigonal pyramidal NHC-stabilized silyliumylidenes .…”

Synthesis of Nitrogen‐Containing Polyaromatics by Aza‐Annulative π‐Extension of Unfunctionalized Aromatics

“…Following this work, computational investigations were carried out on the reaction mechanism of the current aza-APEX reaction of 1a with 2a and AgPF 6 .B ased on the literature [12] and our hypothesis that N-phenyl benzonitrilium hexafluorophosphate (5)o ri ts equivalent imidoyl fluoride-PF 5 complex 5' ' would be initially formed by the reaction of 2a with AgPF 6 (Figure 2a), computations were performed using Gaussian 16, revision C.01, [13] with the M06-2X [14] density function. According to the literature, [15] geometry optimizations and frequency calculations of the all minima and transition states using the 6-31 + G(d) level of theory,i nt he gas phase at 353.15 K, were calculated by single-point calculations of optimized geometries with the 6-311 ++G-(d,p) level of theory at 353.15 Ki n1 ,2-dichloroethane (IEF-PCM [16] ).…”

Multinuclear Cu(I) Clusters Featuring a New Triply Bridging Coordination Mode of Phosphaamidinate Ligands

“…The phosphabenzamidine 1 was synthesized by adopting the synthetic routes reported in the literature, , utilizing N -benzylidyne-2,4,6-trimethyl­benzen­aminium triflate ( C ) and mesityl­phosphane ( D ) (Scheme ). The reaction conditions drive a 1,3 hydrogen shift to afford 1a (∼80%) and 1b (∼20%).…”

“…However, phosphaamidinates do not coordinate to Au­(I) in a similar fashion. The Lammertsma group reported two coordination complexes of phosphaamidinates with Rh­(I) and Au­(I) . In the Rh­(I) complex, the phosphaamidinate ligand chelates to a single Rh­(I) center, whereas the Au­(I) complex displays μ 2 -P, bridging without any N-coordination (Chart (ii), (iv)).…”

“…In contrast, the coordination chemistry of phosphaamidinate analogues, [RNC­(R′)­PR] − , is less well-known since the initial discovery of phosphorus–carbon multiple bond chemistry by Issleib et al in 1978, and only a few examples of metal phosphaamidinate complexes are reported, including Pt­(II) and Rh­(I) examples with N,P-chelation, , a Tl­(I) complex with P,π-aryl-chelation, and a trinuclear-Au­(I) complex with μ 2 -P bridging . (Chart ).…”