The First Six-Membered “True” Heterocycle – Hydrogen-Bond-Assisted Ladder Formation in a KOCNPS Ring System

A ladder of alternating K₂S₂ and K₂O₂ rings exists in K[Ph₂P(S)NC(O)Ph]⋅MeOH, the first six-membered “true” heterocycle, in the solid state (see picture). A simple P–N bond-forming reaction between benzamide and Ph₂PCl gives the precursor Ph₂P(S)NHC(O)Ph, from which the potassium salt can be generated by reaction with KOtBu.     

Reduction of Phosphine Oxide by Using Chlorination Reagents and Dihydrogen: DFT Mechanistic Insights

Extensive DFT calculations provide detailed mechanistic insights into the metal-free reduction of phosphine oxide Ph₃P=O by using chlorination reagents O=CClX (X=COCl, Cl, OCCl₃ and Ph) and H₂. Fast electrophilic attack to the P=O group oxygen atom is favored by exergonic CO₂ release to form phosphonium Ph₃PCl⁺ and chloride Cl⁻, which may slowly cleave H₂ by an unstable HPh₃PCl complex yielding Ph₃PH⁺ and Cl⁻ ions in solution. Moderate heating is required to accelerate the slow H₂-activation step and to eliminate HCl to form phosphine Ph₃P instead of Ph₃PH⁺Cl⁻ salt as the desired product. Though partially quenched by Ph₃P (and reactant Ph₃P=O if present), borane B(2,6-F₂C₆H₃)₃ can be still combined with Cl⁻ and Ph₃P as reactive frustrated Lewis pair (FLP) catalysts.     

Interaction of PH3 with acetaldehyde in aqueous media and chemistry of [HO(Me)CH]4PCl

The known phosphonium chloride [HO(Me)CH]₄PCl was prepared at ambient conditions from PH₃ and acetaldehyde in aqueous HCl, and characterized by elemental analysis and ¹H and ³¹{¹H} NMR spectroscopy. Attempts to obtain the tertiary phosphine [HO(Me)CH]₃P via reaction of [HO(Me)CH]₄PCl with Na₂SO₃ or Et₃N in aqueous media under Ar revealed that [HO(Me)CH]₃P is unstable and equilibrates with the secondary phosphine [HO(Me)CH]₂PH and acetaldehyde. A 1:4 reaction of [HO(Me)CH]₄PCl with NaHSO₃ at room temperature under Ar affords first the oxide [HO(Me)CH]₂P(O)H and then the phosphinic acid [HO(Me)CH]₂P(O)OH. A 1:1 reaction of [HO(Me)CH]₄PCl with Na₂S₂O₃ affords the sulfide [HO(Me)CH]₃PS. ³¹{¹H} and ¹H NMR data for all the (α-hydroxyethyl)phosphorus species are reported for the first time.     

Tris(tetramethylguanidinyl)phosphine: The Simplest Non-ionic Phosphorus Superbase and Strongly Donating Phosphine Ligand

We report the synthesis and properties of the much sought-after tris(1,1,3,3-tetramethylguanidinyl) phosphine P(tmg)₃, a crystalline, superbasic phosphine accessible through a short and scalable procedure from the cheap and commercially available bulk chemicals 1,1,3,3-tetramethylguanidine, tris(dimethylamino)-phosphine and phosphorus trichloride. The new phosphine exhibits exceptional electron donor properties and readily forms transition metal complexes with gold(I), palladium(II) and rhodium(I) precursors. The formation of zwitterionic Lewis base adducts with carbon dioxide and sulfur dioxide was explored. In addition, the complete series of phosphine chalcogenides was prepared from the reaction of P(tmg)₃ with N₂O and the elemental chalcogens.     

Phosphine-substituted diiron 1,2-dithiolate complexes as the models for the active site of [FeFe]-hydrogenases

Abstract

In this article, five diiron 1,2-dithiolate complexes containing phosphine ligands are reported. Treatment of complex [Fe₂(CO)₆(μ-SCH₂CH₂S)] (1) with the phosphine ligands tris(4-methylphenyl)phosphine, tris(4-methoxyphenyl)phosphine, tris(3-chlorophenyl)phosphine, tris(3-methylphenyl)phosphine, or 2-(diphenylphosphino)biphenyl in the presence of Me₃NO·2H₂O as the decarbonylating agent afforded the target products [Fe₂(CO)₅(L)(μ-SCH₂CH₂S)] [L?=?P(4-C₆H₄CH₃)₃, 2; P(4-C₆H₄OCH₃)₃, 3; P(3-C₆H₄Cl)₃, 4; P(3-C₆H₄CH₃)₃, 5; Ph₂P(2-C₆H₄Ph), 6] in 80–93% yields. Complexes 2–6 have been characterized by elemental analysis, spectroscopy, and X-ray crystallography. Additionally, the electrochemical properties were studied by cyclic voltammetry.     

Synthese und Struktur der ersten sechsgliedrigen Selena- und Platinatriazaphosphorine

Synthesis and Strukture of the First Six-membered Selena- and Platinatriazaphosphorines The reaction of PhCN with Li[N(SiMe₃)₂], Ph₂PCl and Me₃SiN₃ leads to the starting material (Me₃Si)₂NC(Ph)NP(Ph)₂N(SiMe₃) 1 . 1-Chloro-3,3,5-triphenyl-1λ⁴, 2,4,6,3λ⁵-selenatriazaphosphorine 2 is formed when 1 is treated with SeCl₄. (Ph₃P)₂Pt(C₂H₄) as well as (Ph₃P)₄Pt react with 1 to yield the six-membered platinum containing heterocycles 2 and 4 . The six-membered rings 2 and 4 were characterized by and X-ray single crystal structure analysis.     

The Synthesis,Characterisation, and Reactivity of Some Polydentate Phosphinoamine Ligands with Benzene‐1,3‐diyl and Pyridine‐2,6‐diyl Backbones

The polydentate phosphinoamines 1,3‐{(Ph₂P)₂N}₂C₆H₄ and 2,6‐{(Ph₂P)₂N}₂C₅H₃N have been prepared in a single step from the reaction of the amines 1,3‐(NH₂)₂C₆H₄ or 2,6‐(NH₂)₂C₅H₃N with Ph₂PCl in presence of Et₃N (1 : 4 : 4 molar ratio) in CH₂Cl₂. Reaction of 1,3‐{(Ph₂P)₂N}₂C₆H₄ or 2,6‐{(Ph₂P)₂N}₂C₅H₃N with elemental sulfur or selenium in CH₂Cl₂ affords the corresponding tetrasulfide or tetraselenide, respectively, in good yield. The complexes [1,3‐{Mo(CO)₄(Ph₂P)₂N}₂(C₆H₄)] and [2,6‐{Mo(CO)₄(Ph₂P)₂N}₂(C₅H₃N)] were prepared from the reaction of these phosphinoamines with [Mo(CO)₄(nbd)] (nbd=norbornadiene) in toluene, and the structure of the latter complex has been determined by single‐crystal X‐ray diffraction analysis.     

Synthesis,characterization, and electrochemistry of monophosphine‐containing diiron propane‐1,2‐dithiolate complexes related to the active site of [FeFe]‐hydrogenases

Five monophosphine‐substituted diiron propane‐1,2‐dithiolate complexes as the active site models of [FeFe]‐hydrogenases have been synthesized and characterized. Reactions of complex [Fe₂(CO)₆{μ‐SCH₂CH(CH₃)S}] ( 1 ) with a monophosphine ligand tris(4‐methylphenyl)phosphine, diphenyl‐2‐pyridylphosphine, tris(4‐chlorophenyl)phosphine, triphenylphosphine, or tris(4‐fluorophenyl)phosphine in the presence of the oxidative agent Me₃NO·2H₂O gave the monophosphine‐substituted diiron complexes [Fe₂(CO)₅(L){μ‐SCH₂CH(CH₃)S}] [L = P(4‐C₆H₄CH₃)₃, 2 ; Ph₂P(2‐C₅H₄N), 3 ; P(4‐C₆H₄Cl)₃, 4 ; PPh₃, 5 ; P(4‐C₆H₄F)₃, 6 ] in 81%–94% yields. Complexes 2 – 6 have been characterized by elemental analysis, spectroscopy, and X‐ray crystallography. In addition, electrochemical studies revealed that these complexes can catalyze the reduction of protons to H₂ in the presence of HOAc.     

Synthesis,characterization, and electrochemistry of phosphine-substituted diiron butane-1,2-dithiolate complexes

Abstract

The reactions of the starting complex, [Fe₂(CO)₆{μ-SCH₂CH (CH₂CH₃)S}] (1), with the phosphine ligands tris(4-methylphenyl)phosphine, diphenyl-2-pyridylphosphine, tris(4-fluorophenyl)phosphine, 2-(diphenylphosphino)benzaldehyde, or benzyldiphenylphosphine in the presence of the decarbonylating agent Me₃NO·2H₂O yielded the corresponding phosphine-substituted diiron butane-1,2-dithiolate complexes [Fe₂(CO)₅(L){μ-SCH₂CH(CH₂CH₃)S}] (L?=?P(4-C₆H₄CH₃)₃, 2; Ph₂P(2-C₅H₄N), 3; P(4-C₆H₄F)₃, 4; Ph₂P(2-C₆H₄CHO), 5; Ph₂PCH₂Ph, 6) in 75%–87% yields. The complexes have been characterized by elemental analysis, IR, ¹H, and ³¹P{¹H} NMR spectroscopy, as well as by single-crystal X-ray diffraction analysis. Moreover, the electrochemistry of 2–4 was studied by cyclic voltammetry, suggesting that they can catalyze the reduction of protons to H₂ in the presence of HOAc.     

Zur Reaktion von Triphenylphosphan mit Thionylchlorid

Triphenylphosphine reacts with thionyl chloride to give [Ph₃PCl]Cl, Ph₃PO and Ph₃PS the formation of the anions S(O)Cl and SCl being discussed; the crystal structure of [Ph₃PCl]Cl · S(O)Cl₂ is reported.     

Substitutions- und Oxydationsreaktionen des N-Dichlorphosphanyl-triphenylphosphazens,Ph3PN?PCl2

Replacement and Oxidation Reactions of N-Dichlorophosphanyl Triphenylphosphazene, Ph₃P?N? PCl₂ The title compound ( 1 ) reacts with MeOH, EtOH, PhOH, EtSH, and water forming N-phosphanyl or N-phosphinoyl phosphazenes, resp., Ph₃P?N? PX₂ (X ? OPh( 8 ), SEt( 9 )) or Ph₃P?N? PH(O)X (X ? Cl( 3 ), OH( 4 ), OMe( 5 ), OEt( 7 )). The reaction of 1 with P(NEt₂)₃ yields Ph₃P?N? P(NEt₂)₂ ( 10 ). Ph₃P?N? PF₂( 11 ) and Ph₃P?N? PH(O)F ( 12 ) are obtained by chlorine-fluorine exchange. The N-phosphanyl compounds 1 , 8 , 9 and 11 are oxidized by NO₂ yielding the corresponding N-phosphoryl derivatives, Ph₃P?N? P(O)X₂ (X ? Cl( 2 ), OPh( 13 ), SEt ( 14 ), F( 15 )). The thiophosphoryl compounds, (Ph₃P?N? P(S)X₂ (X ? Cl( 16 ), OPh( 17 ), F( 18 )) are obtained by oxidizing 1 , 8 , and 11 with sulfur.     

Unusual nitrogen based heterocycles via allenic intermediates from the reaction of propargyl alcohols with P(III) substrates

The apparently simple reaction of the P(III) precursors [(RNH)P(μ-N-t-Bu)₂PY] (Y=NH-t-Bu, Cl), (OCH₂CMe₂CH₂O)PCl, and Ph₂PCl with functionalized propargyl alcohols is examined. In most cases, the final products are not the expected allenes but several previously unpredicted structural motifs, such as substituted oxazabenzocycloheptenones, indolinones, and fused heterocycles as revealed by X-ray crystallography. Mechanistic aspects of these novel reactions, as well as possible utility and the structural chemistry of the products are also discussed. The P–C or P–N bond cleavage of many of these compounds led to phosphorus-free 2-substituted indoles, quinolinones, and tetrahydroacridine.     

2-Cyanoacrylates as reagents in heteroatomic synthesis (a review)

Several types of addition reactions to the CC bond of alkyl 2-cyanoacrylates, CH₂C(CN)COOR ( 1 ), are considered. The first examples deal with addition of CH-Acids (p K _a less than 13) and of H₂S in the presence of catalytic amounts of strong amines, also of mercaptans, thiocarboxylic, and thiophosphoric acids. P-Sulfenylchlorides and acidic phosphites add irreversibly at 20°C to form addition products in accordance with the distribution of charges in 1 . HCl reversibly adds to 1 and to the acid chloride CH₂C(CN)COCl ( 2 ). Alcohols and H₂O also add reversibly to the acid CH₂C(CN)COOH ( 3 ) and to esters of 1 to transform 1 and 3 into polymers. Triethylsilane in the presence of CF₃COOH ( 4 ) reduces the CC bond of 1 and 3 to the corresponding saturated derivatives. The second set of examples involves reactions of 1 with P-III compounds in the presence or absence of 4 . Ph₃P as well as other weak nucleophiles reversibly add to 1 in the absence of 4 to cause instant polymerization. However, 4 protonates an initially formed zwitter-ion in the reaction of 1 with Ph₃P,(EtO)₂PCl,Ph₂PCl and thiourea to afford stable addition products. IR spectroscopy reveals the formation of H-complexes of 4 with the CN and COOR groups of 1 , which stimulates the addition of the weak nucleophile (o-C₆H₄O₂)PCl to the CC bond of 1 . This reagent does not react with 1 in the absence of 4 . Strong nucleophiles, Alk₃P, and (Et₂N)₃P in excess irreversibly add at 20°C to 1 to form zwitterions, which specifically react with PhNCO to give stable products. 1,3,2-Dioxaphospholes react with 1 either to form spirophosphoranes or 2-cyano-3-phosphoranylpropionates.     

Tetracarbonylwolfram-komplexe mit zwei unterschiedlichen donorliganden : I. Darstellung und mechanismus der thermischen isomerisierung

cis- and trans-tetracarbonyltungsten complexes (R₃P)(R′₃E)W(CO)₄ (R₃P,R′₃E = i-Pr₃P, Ph₂-i-PrP, Ph₃P, Ph₂HP, (Me₂n)₃P, Ph(i-PrO)₂P, (i-PrO)₃P, (PhO)₃P, Ph₃As, Ph₃Sb) are obtained from the chlortetracarbonyltungstates [(R₃P)W-(CO)₄Cl]^- by several different routes. a cis—trans equilibrium is attained at 20–30°C with the trans isomer being thermodynamically more stable in nearly all cases. The cis-trans isomerisation of the phosphine—arsine and phosphine—stibine complexes is shown by ligand exchange experiments to occur via dissociation of the arsine and stibine ligand, respectively. The bis(phosphine) complexes, however, isomerise intramolecularly without bond cleavage.     

Tetracarbonylwolfram-komplexe mit zwei unterschiedlichen donorliganden : II. Photochemische ligandensubstitution an trans-bis(phosphin)-komplexen

Tungsten (0) complexes trans-LL′W(CO)₄ (L ≠ L′: i-Pr₃P, Ph₃P, (Me₂N)₃P, (i-PrO)₃P (PhO)₃P) fall into two categories with respect to their photochemistry. Compounds of type A, which contain at least one strongly donating phosphine ligand, lose one of the axial phosphines upon irradiation. Of the two different phosphines, one is always lost preferentially, with the photochemical lability increasing in the series (Me₂N)₃P < (i-PrO)₃P₃P < (PhO)₃P < Ph₃P. Compounds of type B, which contain weakly donating phosphine ligands only, lose one of the radial carbonyl groups upon irradiation. These results are explained in terms of ligand field theory and Vanquickenborne's labilisation model.     

Aminophosphines Derived From 1-Amino-4-Methylpiperazine: Synthesis,Oxidation and Complexation Reactions

Abstract

Functionalized mono(amino)phosphines of the type Ph₂PNHR (1) and bis (amino)phosphine of the type PhP(NHR)₂ (2) have been synthesized by treating Ph₂PCl or PhPCl₂ with 1-amino-4-methylpiperazine. Ligands react with aqueous hydrogen peroxide, elemental sulfur, or selenium to give the corresponding chalcogenides in good yields. The molybdenum complexes of the aminophosphines have been obtained. All of the new compounds were characterized by IR, ¹H, and ³¹P-NMR spectroscopy and elemental analysis.     

Tris(2‐pyridyl)­phosphine oxide: how C—H⃛O and C—H⃛N interactions can affect crystal packing efficiency

Tris(2‐pyridyl)­phosphine oxide, (I), C₁₅H₁₂N₃OP, is isomorphous with tris(2‐pyridyl)­phosphine. Because of a combination of C—H⋯O and C—H⋯N interactions, the crystal packing is denser in the title compound than in the related compounds tri­phenyl­phosphine oxide and tris(2‐pyridyl)­phosphine.     

Symmetrische,phosphorsubstituierte Carbodiimide

Ph ₂PCl,Ph ₂(O)Cl andPh ₂(S)Cl react with Ag₂CN₂ to give symmetric, phosphorus substituted carbodiimides. N,N′-Bis-(diphenylphosphine)carbodiimide is stable only as its AgX-complex. Reaction with water yields the corresponding ureas.     

2-Cyanoacrylates in the conjugate addition of trifluoroacetic acid and nucleophilic reagents

In the presence of trifluoroacetic acid, ethyl 2-cyanoacrylate readily reacts with nucleophilic reagents, such as 2-chloro-1,3,2-benzodioxaphosphole, (EtO)₃P, (EtO)₂PCl, Ph₂PCl, Ph₃P, and thiourea. In these reactions the acid proton enters position 2 of the cyanoacrylate, whereas the nucleophilic component enters position 3, in accordance with the electron density distribution in the acrylate. In the absence of trifluoroacetic acid the above reagents, except 2-chloro-1,3,2-benzodioxaphosphole, cause ethyl 2-cyanoacrylate polymerization. The interaction of ethyl 2-cyanoacrylate with 2-chloro-1,3,2-benzodioxaphosphole and trifluoroacetic acid is the first example of a 2-cyanoacrylate taking part in the acid-initiated electrophilic conjugate addition of a weak nucleophile.Translated fromIzvestiya Akademii Nauk. Seriya Khimicheskaya, No. 7, pp. 1245–1247, July, 1993.     

Ligating characteristic of an unstable phosphorus(III) derivative diphenylisothiocyanatophosphine; Synthesis and characterization of its chelates with transition metal ions

Summary Diphenylisothiocyanatophosphine prepared in CHCl₃ solution from Ph₂PCl and AgSCN yields stable complexes with MCl₂, Cu₂Cl₂, [Ni(Ph₃P)₂Cl₂] or [Cu(Ph₃P)₃Cl] which have the stoichiometry [MLCl₂], [M=Ni(1) or Cu(2)], [CuLCl](3), [Ni(Ph₃P)-(Ph₂PNCS)Cl₂](4) and [Cu(Ph₃P)(Ph₂PNCS)Cl](5) respectively characterized by physicochemical methods. The>PNCS moiety retains its entity in the complexes providing both P and S as chelating centres. The geometry of the complexes has been determined from magnetic susceptibility and electronic spectral measurements.