Reactions of trans-Carbonyl(Chloro)-[Bis(Triphenylphosphine)]Rhodium(I) with Substituted Cyclopentadienyl Tricarbonyl Molybdenum Anions

Reactions of trans-carbonyl(chloro)[bis(triphenylphosphine)]rhodium(I): trans-ClRh(CO)(PPh₃)₂ with substituted cyclopentadienyl tricarbonyl molybdenum anions, [Mo(CO)₃(η ⁵ -C₅H₄R)]^? (R=H; COCH₃) in tetrahydrofuran (THF) at 55°C for 24 h yielded two monometallic complexes as by-products: [Rh(CO)(PPh₃)(η⁵-C₅H₄R)] (R = H (1a); COCH₃ (2a)) and two main heterobimetallic compounds: [RhMo(CO)₄(PPh₃)₂(η⁵-C₅H₄R)] (R = H (1b); COCH₃ (2b)). These compounds were characterized by elemental analysis, IR and ¹H NMR spectra. The molecular structure of (2a) was determined by X-ray diffraction.     

Phosphorus Centers of Different Hybridization in Phosphaalkene‐Substituted Phospholes

Phosphole‐substituted phosphaalkenes (PPAs) of the general formula Mes*P?C(CH₃)?(C₄H₂P(Ph))?R 5 a – c (Mes*=2,4,6‐tBu₃Ph; R=2‐pyridyl ( a ), 2‐thienyl ( b ), phenyl ( c )) have been prepared from octa‐1,7‐diyne‐substituted phosphaalkenes by utilizing the Fagan–Nugent route. The presence of two differently hybridized phosphorus centers (σ²,λ³ and σ³,λ³) in 5 offers the possibility to selectively tune the HOMO–LUMO gap of the compounds by utilizing the different reactivity of the two phosphorus heteroatoms. Oxidation of 5 a – c by sulfur proceeds exclusively at the σ³,λ³‐phosphorus atom, thus giving rise to the corresponding thioxophospholes 6 a – c . Similarly, 5 a is selectively coordinated by AuCl at the σ³,λ³‐phosphorus atom. Subsequent second AuCl coordination at the σ²,λ³‐phosphorus heteroatom results in a dimetallic species that is characterized by a gold–gold interaction that provokes a change in π conjugation. Spectroscopic, electrochemical, and theoretical investigations show that the phosphaalkene and the phosphole both have a sizable impact on the electronic properties of the compounds. The presence of the phosphaalkene unit induces a decrease of the HOMO–LUMO gap relative to reference phosphole‐containing π systems that lack a P?C substituent.     

Phosphites and Hexafluoroacetone-Hexafluoroacetylacetones: a Comparison

Abstract

Selected acyclic and cyclic phosphites (RO)₂PX (1-5) were reacted with activated ketones (CF₃)₂CO (6) and Z-CF₃C(O)CH=C(OH)CF₃ (7a) / E-CF₃C(O)CH=C(OSiMe₃)CF₃ (7b) in order to study the influence of R and X on the product formation. A new type of insertion, a 1,4 group shift and cyclo-addition reactions yielding five membered rings and bicyclic fused systems were observed. In most cases phosphonates and their λ⁵[sgrave]⁵ P derivatives were obtained. The ketones in question can be considered versatile reactants in phosphorus chemistry.     

Conformational Behaviour of Substituted 2-Methoxy-2-Oxo-1,2-Oxaphospholan-3-Ols

Abstract

Conformational behaviour of about 30 2-methoxy-2-oxo-1,2- oxaphospho l an-3-0 1 s containing various substituents was examined by ¹H and ¹³C NMR. Vicinal coupling constants J(HCCH), J(HCCP), J(HCOP), J(CCOP) and J(CCCP) were employed in this study. Conformation of the 1,2-oxaphospholane ring is governed almost exclusively by substituents at C-3, C-4 and C-5, as we l l as by their orientation. The configuration of the P atom has little or no influence on conformation of the ring in diastsreomeric pairs. Strong preference of phenyl, methyl and substituted methyl groups to occupy the equatorial or pseudoequatoria l positions was observed for all but one compounds studied. In the cis-fused bicyclic syst ems conformat ionally rigid 6-membered rings forced the 1,2-oxaphospholane rings to adopt an enve l ope-l ike (E₄) conformation. No influence of the p=o……HO-C-3 hydrogen bond on conformation of the 1,2-oxaphospholane ring was found. Preferred conformations for (2R, 3R, 4R)-3-(hydroxymethyI)-2-methoxy-2-oxo-1,2-oxaphospho lane-3,4-diol and its triacetate are shown below.     

Reactivity of ortho‐Substituted Aryl–Palladium Complexes towards Carbodiimides,Isothiocyanates, Nitriles,and Cyanamides

Complexes [Pd(C₆H₃XH‐2‐R′‐5)Y(N^N)] (X=O, NH; Y=Br, I; R′=H, NO₂; N^N=N,N,N′,N′‐tetramethylethylenediamine (tmeda), 2,2′‐bipyridine (bpy), 4,4′‐di‐tert‐butyl‐2,2′‐bipyridine (dtbbpy)) react with RN?C?E (E=NR, S) or RC≡N (R=alkyl, aryl, NR′′₂) and TlOTf (OTf=CF₃SO₃) to give, respectively, 1) products of the insertion of the C?E group into the C? Pd bond, protonation of the N atom, and coordination of X to Pd, [Pd{κ²‐X,E‐(XC₆H₃{EC(NHR)}‐2‐R′‐4)}(N^N)]OTf or [Pd(κ²‐X,N‐{ZC₆H₃(NH?CR)‐2‐R′‐4})(N^N)]OTf, or products of the coordination of carbodiimides and OH addition, [Pd{κ²‐C,N‐(C₆H₄{OC(NR)}NHR‐2)}(bpy)]OTf; or 2) products of the insertion of the C≡N group to Pd and N‐protonation, [Pd(κ²‐X,N‐{XC₆H₃(NH?CR)‐2‐R′‐4})(N^N)]OTf.     

Synthesis and Reactions of the Novel Diphosphine,iPrN = C[CH2P(NiPr2)2]2

Abstract

The aldimine nBuN=CHiPr and phosphorus trichloride react to give phosphorus(III) amides in a 1:1 and 2:1 molar ratio. An imine-enamine tautomerism is proposed. In a [4+1] cycloaddition reaction diacetyl-(N-n-butyl)diimine and λ³σ³P-species, RPCl₂ or EtOPCl₂, form 1,2,3λ⁵σ⁴ -diazaphospholenes¹. The same diimine and (Et₂N)₂ PCl is furnishing annellated azaphospholenes¹. A 1,3,4λ⁵ σ⁴ -diazaphospholanium is formed from a λ³σ³ -phosphenium and iPrN=CMe₂ ². Phosphorus(III) amides P(NR₂)₃ (R= Me, Et) and O-trimethylsilylated diacetyldioxime give rise to yield the first monocyclic pentaazaphosphoranes.     

Preferred Conformations of Stabilized Phosphorus Ylides

The stabilized phosphorus ylides, Ph₃P=C(CO.R′)CO.OR; 1, R=Et, R′=CH₂P⁺Ph₃; 2, R=R′=Me; 3, R=Et, R′=Me; 4, R=Prⁱ; R′=Me; 5, R=Bu^t; R′=Me, adopt a near planar conformation in the crystal which allows extensive electronic delocalization. The keto and alkoxylic oxygens are oriented and align favorably with the cationoid phosphorus. These conformations bring methyl hydrogens in the ester residue into proximity with the face of a phenyl group and lead to π-shielding and upfield shifts of the ¹HNMR signals of 3 over a wide temperature range (-50–95°C) in (CD₃)₂CO, CDCl₃ and DMSO_d-6. Geometries of 2 and 3, optimized by using the HF 3-21 (G^*) or 6-31 (G^*) basis sets, are very similar to those in the crystal, but semiempirical treatments generate structures in which either the ester or keto moiety is twisted out of plane.

     

Syntheses and crystal structures of Dimolybdenum complexes containing P2 and functionalized Cyclopentadienyl ligands

The dimolybdenum complex [(η⁵-RC₅H₄)₂Mo₂(CO)₆] (1, R = CH₃CO; II, R = CH₃O₂C) reacts with an equimolar amount of white phosphorus P₄ to yield the corresponding dimolybdenum complex containing the P₂ ligand [(η⁵-RC₅H₄)₂Mo₂(CO)₄(μ,η²-P₂)] (1, R = CH₃CO; 2, R = CH₃O₂C) in moderate yield. The two new compounds have been characterized by elemental analyses, ¹H?NMR, ¹³C?NMR, ³¹ P?NMR and IR spectroscopies and their crystal structures have been determined by X-ray diffraction methods.     

Imides of 2-Trifluoroacetylphenol and other Trifluoracetic acid Esters: Novel Reactions with Phosphorus(III) Derivates

Abstract

The imido derivates of 2-trifluoroacetylphenol, 1 (R¹=H, Me, iPr) react with the isocyanatophosphites (R²O)₂PNCO, 2 (R²[dbnd]Et, R²-R²[dbnd]CMe₂-CMe₂) to yield the bicyclic compounds 3, wheras in case of 1 (R¹[dbnd](CH₂)₂NMe2) the λ³σ³P compounds 4 are found. The phosphorus(III) chlorides R3PC12 (R³[dbnd]Ph, OEt) and 1 (R¹[dbnd]H, Me) give rise to furnish the tricyclic phosphoranes 5. However with 1 (R¹[dbnd]iPr) phosphite 6 is obtained, which adds hexafluoracetone to give the 1,3,2λ⁵σ⁵-dioxaphospholane 7. 2-(Trifluoracetoxy)pyridine 8. reacts with Tris(trimethylsily1)phosphite to yield the bis(phosph0nate) 10. Some molecular structures are discussed on the basis of x-ray diffraction results.     

New Look into the Synthesis of Polyhalogenoarylphosphanes

The present study shows new aspects of the synthesis of polyhalogenoarylphosphanes. The sterically hindered anions Ph(R)P-Y^? (1a–c, Y = O, lone pair; R = Ph, Bu^t) have been used to show the complexity of the reaction between phosphorus nucleophiles and hexahalogenobenzenes or 9-bromofluorene (E3). The Ph(Bu^t)P-O^? (1a) anion reacts with hexachlorobenzene (E1), hexafluorobenzene (E2), or E3 to give Ph(R)P(O)X (4a–c, X = F, Cl, Br) with the release of the corresponding carbanion as a nucleofuge, followed by side reactions. In contrast, the lithium phosphides Ph(R)PLi (1b,c) react with hexahalogenobenzenes to give the corresponding diphosphanes 5a,b as the main product and traces of P-arylated products, i.e., Ph(R)P-C₆X₅ (10a,b, X = Cl, F). Unexpectedly, Ph(Bu^t)PLi (1b) reacts with an excess of 9-bromofluorene to give only halogenophosphane Ph(Bu^t)P-X.     

Substituted 1,3,2,4‐benzodithiadiazines and related compounds

Despite some limitations, the 1:1 condensation of n‐RC₆H₄‐N=S=N‐SiMe₃ (n = 2, 3, 4; R = CH₃, OCH₃, F, Cl, CF₃) with SCl₂, followed by intramolecular electrophilic ortho‐cyclization, was found to be a general synthetic approach to the corresponding 5‐R, 6‐R, and 7‐R–substituted 1,3,2,4‐benzodithiadiazines, formally antiaromatic 12π‐electron compounds. For precursors with n = 3, the high regioselectivity of the cyclization resulted in exclusive (R = OCH₃, F) or predominant (R = CH₃, Cl) formation of 6‐R isomers; the ratio of the major 6‐R isomer to the minor 8‐R one was found to be 72:28 (R = CH₃) or 78:22 (R = Cl). The preferred direction of cyclization is consistent with thermodynamics of the corresponding intermediate σ‐complexes as well as factors of kinetic control for an orbital‐controlled El‐Nu reaction. According to the X‐ray diffraction data, the molecules of 5‐CF₃ (15) and 6‐F (12) derivatives are nearly planar, while the molecules of 5‐OCH₃ (7) and 6‐CH₃ (4) derivatives are bent along the S¹ … N⁴ line by ∼11° (7) or 7° (4). An attempt to adopt CsF‐induced intramolecular nucleophilic ortho‐cyclization of Ar_F‐S‐N=S=N‐SiMe₃ into polyfluorinated 1,3,2,4‐benzodithiadiazines for polyfluoropyridine derivatives resulted in formation of polyfluorinated aminopyridines. Data obtained are consistent with a previously suggested scheme of sulfur–nitrogen chain shortening during cyclization. Mild acid hydrolysis of the title compounds was shown to be a convenient synthetic route to substituted 2,2′‐diaminodiphenyl disulfides (including polyfluorinated ones) via the corresponding 2‐aminobenzenethiols. © 1999 John Wiley & Sons, Inc. Heteroatom Chem 10: 113–124, 1999     

Structural Analysis of Zincocenes with Substituted Cyclopentadienyl Rings

New zincocenes [ZnCp′₂] ( 2 – 5 ) with substituted cyclopentadienyl ligands C₅Me₄H, C₅Me₄tBu, C₅Me₄SiMe₂tBu and C₅Me₄SiMe₃, respectively, have been prepared by the reaction of ZnCl₂ with the appropriate Cp′‐transfer reagent. For a comparative structural study, the known [Zn(C₅H₄SiMe₃)₂] ( 1 ), has also been investigated, along with the mixed‐ring zincocenes [Zn(C₅Me₅)(C₅Me₄SiMe₃)] ( 6 ) and [Zn(C₅Me₅)(C₅H₄SiMe₃)] ( 7 ), the last two obtained by conproportionation of [Zn(C₅Me₅)₂] with 5 or 1 , as appropriate. All new compounds were characterised by NMR spectroscopy, and by X‐ray methods, with the exception of 7 , which yields a side‐product ( C ) upon attempted crystallisation. Compounds 5 and 6 were also investigated by ¹³C CPMAS NMR spectroscopy. Zincocenes 1 and 2 have infinite chain structures with bridging Cp′ ligands, while 3 and 4 exhibit slipped‐sandwich geometries. Compounds 5 and 6 have rigid, η⁵/η¹(σ) structures, in which the monohapto C₅Me₄SiMe₃ ligand is bound to zinc through the silyl‐bearing carbon atom, forming a Zn? C bond of comparable strength to the Zn? Me bond in ZnMe₂. Zincocene 5 has dynamic behaviour in solution, but a rigid η⁵/η¹(σ) structure in the solid state, as revealed by ¹³C CPMAS NMR studies, whereas for 6 the different nature of the Cp′ ligands and of the ring substituents of the η¹‐Cp′ group (Me and SiMe₃) have permitted observation for the first time of the rigid η⁵/η¹ solution structure. Iminoacyl compounds of composition [Zn(η⁵‐C₅Me₄R)(η¹‐C(NXyl)C₅Me₄R)] resulting from the reactions of some of the above zincocenes and CNXyl (Xyl=2,6‐dimethylphenylisocyanide) have also been obtained and characterised.     

Diastereoselective Synthesis of Phosphines and Phosphoranes using Fluorinated Acetylacetones

Abstract

A two step formal insertion of 1,1,1,5,5,5-hexafluoro- (1) and l,l,l - trifluoropentane-2,4-dione (2) into the P-H bonds of phosphane gave the primary a-hydroxyphosphanes. precursors for 2-phospha-6-oxa-9- oxabicyclo[3.3.1]-nonane and 2,4,8-trioxa-6-phospha-adamantane, both formed diastereospecifically. The molecular structures of the two latter compounds were established by single-crystal X-ray structure analysis. Compound 1 reacted diastereospecifically with phosphonous acid dichlorides, RPCl₂ (R = Me, Et, iPr, tBu, Me₃SiCH₂, PhCH₂, Ph) to give in a concerted mechanism thermally stable tricyclicλ⁵σ⁵ P phosphoranes containing two five- and one six-membered ring. In one case hydrolysis gave 3,5-dihydroxy-2-oxo-1,2λ⁵σ⁴-oxaphospholane, whereas methanol added to the double bond in the six-membered ring furnishing two isomeric phosphoranes. When 2 was reacted withRPCl₂ (R = Et, Me₃SiCH₂, PhCH₂. Ph), diastereomerically pure regioisomeric phosphoranes were obtained. The solid state molecular structures of three λ⁵σ⁵P species exhibited two oxygen atoms in the axial position of a slightly distorted trigonal-bipyramidal geometry at phosphorus.     

Study on synthesis of lanthanide chelates of fluorochloroalkyl β-diketones useful as shift reagents

Several lanthanide chelates of the fluorochloroalkyl β-diketones Ln(CF₂ClCOCHCOR)₃ ·nH₂O were prepared (2, Ln=Eu; 2a, R=C(CH₃)₃, n=0; 2b, R=C₆F₅, n=0; 2c, R=CF₂Cl, n=2. 3, Ln=Pr; 3a, R=C (CH₃)₃, n=0; 3b, R=C₆F₅, n=l; 3c, R=CF₂Cl, n=2. 4, Ln=La, R=C₆H₅, n=0) and the NMR shift data of compounds 2 and 3 had been determined using alcohols, ether, ketones and amine as substrates. With alcohol, ether and ketone, compounds 2 induces shifts similar to that induced by Eu (fod)₃. However due to the high solubility of the chelates in non-polar organic solvents such as CHCl₃ and CCl₄ and the absence of ¹H signal from compounds 2b and 2c, their application as a series of new ¹H NMR shift reagents seems promising.     

Phosphorus heterocycles: synthesis,spectroscopic study and X-ray crystallography of some new diazaphosphorinanes

New diazaphosphorinanes with formula R=C₆H₅O (2), 4-CH₃-C₆H₄NH (3), 4-NO₂-C₆H₄NH (4), R=Cl (5), 4-CH₃-C₆H₄O (6), and C₆H₅NH (7) were synthesized and characterized by ¹H, ¹³C, ³¹P NMR and IR spectroscopy and elemental analysis. The crystal structures of compounds 1 and (8) were determined using X-ray crystallography. In these structures, the P=O bond is placed in an equatorial position and the aliphatic six-membered rings show chair conformations. These compounds form two-dimensional polymeric chains via intermolecular P=O…H–N hydrogen bonds. ¹H NMR spectrum of compound 1 shows a ddd splitting pattern for the coupling of H_equatorial proton with phosphorus atom, H_axial atom, and NH proton with a high-value ³ J(PNCH) coupling constant = 26.1 Hz. But, H_axial indicates a dd splitting pattern because of the coupling with H_equatorial and NH protons. ¹³C NMR spectra of compounds 5–7, indicated high values for ³ J(P,C)_aromatic = 11.9, 11.3 and 10.2 Hz due to the coupling of the aromatic carbon atom of naphthalene moiety with the phosphorus atom. ³¹P NMR spectra indicate that the δ(³¹P) of compounds 1–4 and 8 containing NH groups connected to the aliphatic carbon atoms appear downfield relative to those of compounds 5–7 that containing NH groups connected to the aromatic naphthalene group.

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Graphical abstract

     

PIV-PV Coordination Isomerism of Cyclic Phosphorus P-Chloro Imines

The structure of 5-chloromethyl-substituted 1,3,2⁵-diazaphosphorines Cl₂P(NCR)₂CC(Cl)R'₂ (R = H, Cl; R' = Cl, F, CN) and their 1 : 2 solvates with chloroform, and alternative chlorotropy pathways in these compounds with variation of the phosphorus coordination number P^{I V}-P^V were studied by semiempirical MNDO-PM3 calculations in the supermolecular approximation. A possibility for isolating metastable P^V isomers Cl₃P(N = CR)₂C = CR'₂ containing two imine nitrogen atoms in the equatorial positions of the trigonal bipyramid of phosphorus was demonstrated. The models of limited specific solvation of sigmatropic transition states of P-chlorodiazaphosphorines and related bipolar phosphorus halides were examined. Specific solvation levels out the preferableness of the 1,5-sigmatropic transformation of 5-chloromethyl-1,3,2⁵-diazaphosphorines via unstable intermediate [NC(Cl)R]C = CR'₂ over the direct P,C migration of chlorine.     

The Phenylphosphinidene C6H5P is Stable Under Unimolecular Conditions - A Theoretical Prediction

Abstract

As members of the family of low-coordinated phosphorus compounds, the phosphinidenes (RP) containing subvalent phosphorus (σ¹,λ¹-P) are of current interest. Until now, no Organophosphiaidene RP (R=Alkyl, Aryl) is known to be stable in the condensed phase. As the results of trapping experiments are questioned, the formation of RP as intermediates is still doubtful [1]. The mass spectrometric decay of some organophosphorus compounds yields radical cations [C₆,H₅,P]^+? m/z 108. For these species structures 1 and 2 are conceivable:     

PREPARATION AND REACTIONS OF METHYLTHIOMETHYL-SUBSTITUTED PHOSPHORUS HALIDES1

Abstract

Methylthiomethylphosphonous dichloride, MeSCH₂PCI₂ (1), is synthezised by the reaction of MeSCH₂SnBuⁿ, with phosphorus trichloride. Substitution reactions to give MeSCH₂PX₂ (X=NEt₂, OPrⁱ, F, Ph) are described. The phosphorus(III) compounds are readily converted to the corresponding phosphonyl and thiophosphonyl derivatives, MeSCH₂P(Z)X₂ (Z=O, S), and the phosphorane, MeSCH₂PF₄, respectively. Chlorination of the methylene group to give compounds of the type MeSCHCIP(O)X₂ and MeSCCI₂P(O)X₂ is reported.     

üBER DIE INSERTION VON RPS2 IN DIE PN-BINDUNG VON AMINOPHOSPHINEN

Abstract

Aminophosphine des Typs R_n P(NR′₂)_3-n (n= 2, 1, 0; R = Ph, c-Hex, (-)Men, t-Bu; R′= Me, Et, n-Bu) reagieren mit 2, 4-Bis(aryl)-1, 3, 2, 4-dithiadiphosphetan-2, 4-disulfiden (ArPS₂)₂(Ar: Ph, 4-Methoxyphenyl = An, Naphthyl, Thienyl) unter formaler Insertion monomerer {ArPS₂)-Einheiten in eine oder in zwei der λ³-P—N-Bindung zu chiralen Organophosphorverbindungen Ar(R′₂N)P(S)—S—PR_n (NR′₂)_2-n(n = 2, 1, 0) und [Ar(R′₂N)P(S)—]₂PR₂(NR′₂)_1-n (n = 1.0). In diesen werden bei Raumtemperatur bevorzugt die λ³—P—N—und λ³—P—S-Bindungen durch H₂O oder Methanol unter Bildung von Produktgemischen solvolysiert. Mit Chlorwasserstoff bildet sich aus An(Et₂N)P(S)—S—PPh(NEt₂) das An(Et₂ N)P(S)—S—PPh(C1). Addition von Schwefel führt zu Ar(R′₂N)P(S)—S—P(S)R_n (NR′)_2-n (n=2, 1). Die Stereoisomerenbildung der neuen Verbindungen wird besprochen und ihre Struktur sowie die Zusammensetzung der Reaktionsmischungen aus den ³¹P-Spektren hergeleitet.

Aminophosphines R_n P(NR′₂)_3-n (n = 2, 1, 0; R = Ph. c-Hex, (-)Men, t-Bu; R′= Me, Et, n-Bu) react with 2, 4-Bis(aryl)-1, 3, 2, 4-dithiadiphosphetane-2, 4-disulfides (ArPS₂)₂ (Ar: Ph, 4-Methoxyphenyl = An, Naphthyl, Thienyl) under formal insertion of monomeric {ArPS₂)-units in one or in two of the λ³-P—N-bonds to yield chiral organophosphorus compounds Ar(R′₂N)P(S)—S—]₂PR_n (NR′₂)₂ (n = 2, 1, 0) and [Ar(R′₂N)P(S)—S—]₂ PR₂ (NR′₂)_2-n (n = 1, 0). At room temperature chiefly the A—P—N and A³—P—S-bonds in these products are solvolyzed by H, O or methanol with formation of mixtures of compounds. With hydrogen chloride An(Et₂N)P(S)—S—PPh(NEt₂) is converted into An(Et₂N)P(S)—S—PPh(Cl). Addition of sulfur yields Ar(R′₂N)P(S)—S P(S)R_n (NR′₂)_2-n (n = 2, 1). Stereoisomerism of the new compounds is discussed and their structures as well as the composition of reaction mixtures are deduced from “P-NMR-spectra”.