Search

Dichlorophosphoranides featuring N,N-dimethyl-N′-arylformamidine substituents were isolated as individual compounds. Dichlorophosphoranide 9 was prepared by the multicomponent reaction of C-trimethylsilyl-N,N-dimethyl-N′-phenylformamidine and N,N-dimethyl-N′-phenylformamidine with phosphorus trichloride. Its molecular structure derived from a single-crystal X-ray diffraction was compared to the analogous dibromophosphoranide prepared previously by us by the reaction of phosphorus tribromide with N,N-dimethyl-N′-phenylformamidine. It was shown that a chlorophosphine featuring two N,N-dimethyl-N′-mesitylformamidine substituents reacted with hydrogen chloride to form dichlorophosphoranide 11. Its molecular structure was also determined by X-ray analysis and compared with that of closely related dichlorophosphoranide C.

A small library of dinuclear gold(I) complexes with the title ligands has been prepared, encompassing neutral, mono- and dicationic complexes. The luminescence properties of the complexes in the solid state have been evaluated, and it turns out that neutral and monocationic complexes not presenting a rigid metallamacrocyclic structure can exhibit rather strong emissions that extend towards the red region of the visible spectrum. The in vitro anticancer activity of the complexes has been also preliminarly evaluated; cytotoxicity seems to correlate with complex lipophilicity, whereas selectivity towards cancer cells can be apparently enhanced upon a judicious choice of the ligands.

Two novel gold(I) complexes with a phosphoguanidine ligand and with a novel cationic phosphane ligand have been prepared and structurally characterized. The phosphoguanidine ligand supports oxidative addition of biphenylene to the gold(I) centre, though the yield of the reaction is low. The phopshoguanidine gold(I) complexes is also able to efficiently catalyze the hydroamination of phenylacetylene with mesitylamine, whereas the gold(I) complex with the cationic phosphane ligand, due to its more electron-poor character, promotes the hydroarylation of ethyl propiolate with mesitylene.

A method for the synthesis of new C-silyl-N,N-dialkyl-N′-arylformamidines was developed. These derivatives were formed by the deprotonation of N-(trimethylsilyl)formamidinium salts to give the corresponding N-trimethylsilyl carbenes followed by a 1,2-migration of the silyl group. The reactions of C-silylformamidines with phosphorus(III) chlorides were then studied. The reactions between chlorodiphenylphosphane and the C-silylformamidines readily afforded C-phosphanylformamidines in high yields. The reactions of dichlorophosphanes and C-silylformamidines yielded previously unknown phosphanes that feature two formamidine substituents. In the reaction with phosphorus trichloride, the sterically least encumbered formamidine gave a stable two-coordinate compound through the formation of an intermediate tris(phosphane). The reactions of the sterically more encumbered formamidines led to the substitution of only two chlorine atoms to give a chlorophosphane or benzazaphosphole. The structures of key compounds were proven by X-ray crystal structure analyses.

N-Phosphanyl-N-heterocyclic carbenes (NHCPs) featuring a saturated imidazolin-2-ylidene or tetrahydropyrimid-2-ylidene ring have been synthesized and characterized. The free carbenes exhibit good stability and can be stored in the solid state for months at ambient temperature without decomposition. Contrary to imidazoline-based NHCPs, which decompose by ring opening, N-phosphanyltetrahydropyrimid-2-ylidenes isomerize to 2-phosphanyl tetrahydropyrimidines upon heating. The free carbenes are capable of acting as chelating ligands toward palladium(II), forming very stable mononuclear complexes that have been structurally characterized. The catalytic potential of the complexes has been preliminarily assessed in cross-coupling reactions, most notably in the Suzuki coupling of aryl chlorides, where these complexes display promising activity, and in the copper- and amine-free Sonogashira coupling of aryl bromides.

International audience; Herein we report on the synthesis of a set of transient N-(PIII)-phosphanyl and N-(PV)-phosphoroselenoyl acyclic diaminocarbenes by deprotonation of the corresponding formamidinium salts. It is shown that N-(PV)-substituted acyclic diaminocarbenes undergo 1,2-phosphorus shift. Transformations of N-(PIII)-substituted acyclic diaminocarbenes result in tetrahydroquinazolines as final products. The proposed mechanism includes the isomerization of the carbenes into transient azomethine ylides followed by their cyclization via electrophilic aromatic substitution. Introduction of the electron-donating dimetylamino group into the phenyl substituent markedly enhances the rate of the reaction and the yield of the final product. In the case of the morpholine derivative, the corresponding azomethine ylide undergoes opening the morpholine ring giving vinyloxazolidin-2-amine. The results are corroborated by DFT calculations.

The deprotonation of N-di-tert-butylphosphanyl-N-aryl-N′-diisopropylformamidinium salts led to a new type of stable acyclic N-phosphanyl-diaminocarbene (PADC). Carbenes 8a–8d were separated as single compounds. The molecular structure of 8c was determined by X-ray diffraction analysis. The PADC 8 possess an optimal substitution pattern at the nitrogen atoms, and the N–Ccarbene–N bond angle is 120.7°. Structural changes near the carbenic carbon atom, such as substitution of phenyl with mesityl, phosphanyl with selenophosphoryl, or the diisopropylamino group with 2,2,6,6-tetramethylpiperidino, rendered them unstable. The PADCs underwent N,C-phosphorus shifts to afford new C-phosphanylformamidines.

The reactions of (di-tert-butylphosphanyl)amines and P,P-di-tert-butylphosphinoselenoic amides with Alder's dimer were studied. For di-tert-butylphosphanylamines, the reaction proceeds by primary electrophilic attack of Alder's dimer at the phosphorus atom to afford a dicationic salt 3. The deprotonation of 3 led to N-phosphanylformamidine 5 (“phosfam”). Alkyl(di-tert-butylphosphanyl)amines reacted with Alder's dimer in a 2:1 molar ratio to give N-phosphanylformamidinium salts; the second equivalent of (alkylamino)phosphane acts as a base. (Arylamino)phosphanes reacted with Alder's dimer to give benzazaphospholium derivatives. To direct the electrophilic attack of Alder's dimer at the nitrogen atom, phosphinoselenoic amides were used. They reacted with Alder's dimer at the selenium atom followed by a selenium–phosphorus shift to give N-(di-tert-butylphosphoroselenoyl)formamidinium salts. The phosphinoselenoic amides with bulky substituents (adamantyl, tBu) underwent cleavage of the N–alkyl bond to afford phosfams. Various key intermediates such as 3 and 22b were isolated and characterized. A convenient method for the synthesis of carbene precursor PIII and PV N-substituted formamidinium salts was developed.

Neutral dinuclear gold(I) complexes having general formula [Au2Cl2(NHCP)] (NHCP = N-phosphanyl N-heterocyclic carbene) have been synthesized by two different synthetic procedures: i) transmetalation of the NHCP ligand from the corresponding dinuclear silver(I) complex; ii) deprotonation of the corresponding N-phosphanyl azolium/tetrahydropyrimidinium salt in the presence of the gold(I) precursor. Interestingly, although the silver complexes are invariably dinuclear dicationic species of formula [Ag2(NHCP)2](OTf)2, both stoichiometries [Au2(NHCP)2](OTf)2 and [Au2Cl2(NHCP)] are potentially accessible with gold. Preference for either stoichiometry is dictated by the steric properties of the NHCP ligand as well as by a proper choice of the experimental conditions. On the other hand, preparation of copper(I) compounds with [Cu2Cl2(NHCP)] stoichiometry leads to product mixtures and has not led up to now to pure neutral compounds. Both the silver(I) and gold(I) complexes have been structurally characterized.

Complexes of palladium(II) with newly disclosed, N-phosphanyl acyclic diaminocarbene ligands are synthesized for the first time and structurally characterized. The ligands coordinate palladium(II) in a chelating fashion, yielding remarkably stable complexes which can be stored without special precautions in the solid state. Related palladium(II) complexes with an isomerized chelating ligand, formed upon 1,2-migration of the phosphanyl group from the nitrogen to the adjacent carbon atom, have also been isolated in some instances and structurally characterized. The complexes efficiently act as precatalysts for Suzuki coupling reactions of aryl chlorides, where their productivity compares favourably with that of related palladium complexes with acyclic diaminocarbene ligands. In addition, the complexes show a distinct tendency to form as the byproduct the reductive homocoupling product of aryl chloride. This observation, together with ad hoc performed control tests, suggests that Pd colloids are involved in the formation of catalytically competent species.

Correction for ‘Palladium(ii) complexes with chelating N-phosphanyl acyclic diaminocarbenes: synthesis, characterization and catalytic performance in Suzuki couplings’ by Anatoliy Marchenko et al., Dalton Trans., 2016, DOI: 10.1039/c5dt02250a.

The halophilic reactions of the derivatives of PIII R3 P (R = R2N, Alk, Ar) with CCl4, having preparative signifi-cance, are studied thoroughly. As far as the compounds of R2PHlg type are concerned, at the beginning of our re-searches there was was an opinion that the interaction of R2PHlg with CC14 cannot be possible because of the low nucleophility of phosphorus. We determined for the first time that diamidochlorophosphites 1 react with CC14 at the temperature 20°C and form the compounds 2, 3.1

The authors have established that hexaalkyltriamidophosphazo groups are unusually strong electron-donor substituents at P /SUP III/ , causing the extremely high basicity of such compounds. This paper performs methylation of tris (tris (N,N-dimethylamido) phosphazo) phosphate and tris (tris (N,N-dimethylamido) phosphazo) methoxyphosphonium iodide (I) using methyl oxide. The NMR spectra were recorded on a Bruker WP-20 spectrometer, and hexamethyldisiloxane and 85% H/sub 3/PO/sub 4/ were used as the standard.