Diphosphine Disulfides Research Articles

Rhodium-catalyzed P-P bond exchange reaction of diphosphine disulfides.

A rhodium-catalyzed exchange reaction of diphosphine disulfides, a diphosphine oxide, and a diphosphine is developed. Various symmetric diphosphine disulfides containing alkyl and phenyl groups are exchanged, giving equilibrium mixtures, from which unsymmetric diphosphine disulfides are readily separated by silica gel chromatography. The resulting unsymmetric diphosphine disulfide is regioselectively added to an aldehyde.

Crystal structure of bis-(1,1,2,2-tetra-methyl-diphosphane-1,2-di-thione-κ(2) S,S')copper(I) tetra-fluorido-borate.

In the title compound, [Cu(C4H12P2S2)2]BF4, both diphosphine di-sulfide mol-ecules bind to the Cu(I) atom, as chelating ligands via the S atoms, forming a monovalent cation with a slightly distorted tetra-hedral coordination around the Cu(I) atom. The average Cu-S distance is 2.350 (15) Å, with small but possibly significant differences within each chelate ring. Ligand P=S distances average 1.964 (3) Å, and the P-P distances are 2.2262 (13) and 2.2166 (14) Å. The ligand chelate rings are twisted in opposite directions, with one in the λ and one in the δ configuration. Although the anisotropic displacement parameters of the F atoms of the anion are quite large compared to that of the B atom, difference Fourier syntheses indicate only one set of sites for the F atoms. In the crystal, possible C-H⋯F hydrogen bonds may stabilize the orientation. The B-F distances, uncorrected for libration, average 1.359 (6) Å.

Syntheses, characterization, and electrochemistry of compounds containing 1-diphenylphosphino-1′-(di-tert-butylphosphino)ferrocene (dppdtbpf)

The reaction of copper(I) salts CuX (X = Cl, Br, I, CN, SCN), [Cu(CH3CN)4]PF6 with 1-diphenylphosphino-1′-di-tert-butylphosphinoferrocene (dppdtbpf) in 1:1 M ratio in DCM–MeOH (50:50 V/V) at room temperature afforded mono and binuclear compounds having formula [Cu2(μ-Cl)2(κ2-P,P-dppdtbpf)2] (1), [Cu2(μ-Br)2(κ2-P,P-dppdtbpf)2] (2) [Cu2(μ-I)2(κ2-P,P-dppdtbpf)2] (3), [Cu2(μ-CN)2(κ2-P,P-dppdtbpf)2] (4), [Cu2(μ2-SCN)2(κ2-P,P-dppdtbpf)2] (5), and [Cu(κ2-P,P-dppdtbpf)(CH3CN)2]PF6 (6). Reacting palladium(II) complex [Pd(C6H5CN)2Cl2] with dppdtbpf gave mononuclear compound [Pd(κ2-P,P-dppdtbpf)Cl2] (7). The reaction of dppdtbpf with sulfur powder under reflux in chloroform afforded a ferrocene diphosphine disulfide dppSdtbpSf (8). All of the synthesized compounds were characterized by elemental analyses, IR, 1H and 31P NMR, ESI-MS and electronic absorption spectroscopy. Molecular structures for the compounds 5, 6, 7 and 8 were determined crystallographically. Compound 5 exists as centrosymmetric dimer in which the two copper atoms are bonded to two dppdtbpf ligands and two bridging thiocyanate groups in μ2-manner. In cationic compound 6, the copper atom is coordinated to one dppdtbpf ligand in κ2-manner and two acetonitrile molecules, whereas in 7, the palladium(II) adopted cis square-planar geometry by coordinating to one dppdtbpf ligand in κ2-manner and two chlorine atoms. Compound 8 revealed a sandwiched structure with both phosphine groups sulfurized. The electrochemical properties of 1–6 were studied by cyclic voltammetry. Compounds 1–6 exhibited moderately weak to strong luminescence properties, however compounds 7 and 8 are non-emissive in the solution state.

Synthesis and structural characterization of a sterically encumbered ferrocenecarboxamido diphosphine and its platinum(II) complex

{[Bis(2-(diphenylphosphino)ethyl)amino]carbonyl}ferrocene (3), a bulky ferrocenecarboxamido-diphosphine, was prepared in a good yield by the reaction of pentafluorophenyl ferrocenecarboxylate (2) with bis[2-(diphenylphosphino)ethyl]amine. The NMR data (1H VT NMR study in particular) indicated a limited molecular mobility of amide 3 that presumably results from a hindered rotation around the amide C–N bond leading to a non-equivalency of the substituents attached to the amide nitrogen. Compound 3 was further converted to the corresponding diphosphine disulfide 4 and reacted with [PtCl2(cod)] (cod = η2:η2-cycloocta-1,5-diene) to give the symmetric, ligand-bridged diplatinum complex [(μ-3)PtCl2]2 (5) having cis square-planar geometry around the Pt(II) centers. The molecular structures of 4 and 5 were determined by single-crystal X-ray diffraction analysis.

Equilibrium shift in the rhodium-catalyzed acyl transfer reactions

Rhodium/phosphine complexes catalyze equilibrium acyl transfer reactions between acid fluorides, aryl esters, acylphosphine sulfides, and thioesters. The use of appropriate co-substrates to accept heteroatom groups shifted the equilibrium to desired products. Acylphosphine sulfides and aryl esters were converted to acid fluorides using benzoylpentafluorobenzene as the fluoride donor, and the fluorination reaction of thioesters employed (4-tolylthio)pentafluorobenzene. Acid fluorides were converted into acylphosphine sulfides and thioesters using diphosphine disulfides and disulfides/triphenylphosphine, respectively. Aryl esters were obtained from acid fluorides and phenols in the presence of triphenylsilane. Aryl esters, acylphosphine sulfides, and thioesters were also interconverted in the presence of rhodium complexes. These rhodium-catalyzed acyl transfer reactions proceeded under neutral conditions without using acid or base. The involvement of acyl rhodium intermediates in these reactions was suggested by the carbothiolation reaction of thioesters and alkynes.

ChemInform Abstract: Synthesis of Acylphosphine Sulfides by Rhodium‐Catalyzed Reaction of Acid Fluorides and Diphosphine Disulfides.

AbstractThe optimized conditions render possible the preparation of various target compounds as synthetic analogues of carboxylic amides.

Metal-catalyzed phosphinyl ester forming reaction of alcohols and phenols with diphosphine disulfides and a dioxide

Transition metal complexes catalyzed the dialkylphosphinothioation reaction of alcohols and phenols with tetraalkyldiphosphine disulfides in high yields. Phenols were reacted in the presence of RhH(PPh 3) 4 and 1,2-bis(dimethylphosphino)ethane under THF reflux, and alcohols with Pd(OAc) 2 and 1,2-bis(diphenylphosphino)benzene under chlorobenzene reflux. Primary alcohols reacted faster than secondary alcohols under these conditions, and protected tyrosine and serine were phosphinothioated with minimal racemization. Tetraphenyldiphosphine dioxide also underwent the P–O bond formation reaction.

Synthesis of acylphosphine sulfides by rhodium-catalyzed reaction of acid fluorides and diphosphine disulfides

A rhodium complex catalyzed the reaction of acid fluorides and tetraethyldiphosphine disulfide giving acylphosphine sulfides. Aromatic acid fluorides with electron donating p-groups reacted smoothly giving the products in high yields. Aliphatic acid fluorides with secondary and tertiary α-carbons were also converted to alkanoylphosphine sulfides, whereas the reaction of a substrate with an α-methylene carbon was accompanied by enol ester formation.

Atom-sparing synthesis of tertiary diphosphine dichalcogenides from acetylenes and secondary phosphine chalcogenides

Secondary phosphine oxides and phosphine sulfides react with acetylene, methylacetylene, and phenylacetylene in the presence of strong bases (KOH-DMSO, KOH-THF) by the mechanism of double nucleophilic α,β-addition to form tertiary diphosphine dioxides and diphosphine disulfides in high yield (up to 97%).

ChemInform Abstract: Rhodium‐Catalyzed Addition Reaction of Diphosphine Disulfide to Aldehydes and Ketones.

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Rhodium-catalyzed addition reaction of diphosphine disulfide to aldehydes and ketones

In the presence of RhH(PPh 3) 4 and 1,2-bis(diphenylphosphino)ethane, tetramethyldiphosphine disulfide and aldehydes were added producing [1-(dimethylthiophosphinoyloxy)alkyl]dimethylphosphine sulfides in high yields. Acetophenones with electron-withdrawing p-groups also yielded 1,2-adducts.

Rhodium-catalyzed thiophosphinoylation reaction of 1,2-dienes with diphosphine disulfides

In the presence of RhH(PPh 3) 4, the reaction of 1,2-alkadienes, tetramethyldiphosphine disulfide, and camphorsulfonic acid gave ( E)-2-dimethylthiophosphinoyl-2-alkenes. The reaction involved the P–P cleavage and the transfer of the thiophosphinoyl group to 1,2-alkadienes with concomitant formation of thiophosphinic anhydride.

Preparation of complexes formed in the reaction between diironnanocarbonyl and tetraalkyl(phenyl)diphosphine disulfides, R2P(S)P(S)R2 (R=Et, n -Pr, n -Bu, Ph)

Fe2(CO)9 and R2P(S)P(S)R2 (R = Et, n-Pr, n-Bu, Ph) react to form two types of cluster complexes Fe3(CO)9(μ3-S)2 (1), Fe2(CO)6(μ-SPR2)2 (2A)–(2D), [2A, R = Et; 2B, R = n-Pr; 2C, R = n-Bu; 2D, R = Ph]. The complexes result from phosphorus–phosphorus bond scission; in the former sulfur abstraction has also occurred. The complexes have been characterized by elemental analyses, FT-IR and 31P-[1H]-NMR spectroscopy and mass spectrometry.

Synthesis of novel paracyclophanes with linear P,N-containing spacers

Condensation of bis(hydroxymethyl)mesityl-and bis(hydroxymethyl)phenylphosphines with N,N′-disubstituted bis(4-aminophenyl)methanes and bis(4-amino-3-carboxyphenyl)methane occurred as covalent self-assembly spontaneously giving a mixture of trans-and cis-diastereomers of 1,5,19,23-tetra-R′-3,21-di-R-1,5,19,23-tetraaza-3,21-diphospha[5.1.5.1]paracyclophanes as the major products. The trans-isomer (R is mesityl; R′ is methyl) was isolated in the individual state and structurally characterized by X-ray diffraction analysis. Sulfurization of macrocyclic diphosphines (R = Ph; R′ is 3-pyridylmethyl or 4-pyridylmethyl) gave the corresponding diphosphine disulfides, the trans-stereoisomer being isolated in the individual state.

Copper‐Catalyzed anti‐Hydrophosphination Reaction of 1‐Alkynylphosphines with Diphenylphosphine Providing (Z)‐1,2‐Diphosphino‐1‐alkenes.

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Copper-Catalyzed anti-Hydrophosphination Reaction of 1-Alkynylphosphines with Diphenylphosphine Providing (Z)-1,2-Diphosphino-1-alkenes

Hydrophosphination of 1-alkynylphosphines with diphenylphosphine proceeds in an anti fashion under copper catalysis, providing an easy and efficient access to a variety of (Z)-1,2-diphosphino-1-alkenes and their sulfides. The reaction is highly chemoselective and can be performed even in an aqueous medium. The reaction is reliable enough to realize a gram-scale synthesis of (Z)-1,2-diphosphino-1-alkene. Radical reduction of the diphosphine disulfides with tris(trimethylsilyl)silane yields the parent trivalent diphosphines without suffering from the isomerization of the olefinic geometry. Enantioselective hydrogenation of (Z)-3,3-dimethyl-1,2-bis(diphenylthiophosphinyl)-1-butene followed by desulfidation leads to a new chiral bidentate phosphine ligand.

Binuclear complexes of 4-methoxyphenyltellurium trichloride with variably linked diphosphine disulfide ligands

Four neutral ligands of the diphosphine disulfide type with different central linking groups [(CH2)4, (CH2)6, (C6H4)2, and HN-(C6H4)-NH] were reacted with 4-methoxyphenyltellurium trichloride in dichloromethane. The crystallization of products afforded crystals consisting of binuclear addition complexes of 4-MeOC6H4TeCl3 with corresponding ligands. The ligands are coordinated to Te(IV) centres through weak Te–S bonds. The coordination of both tellurium atoms in each complex is pseudo-octahedral, built of the TeCl3S tetragonal basis and the aryl group and the lone pair of electrons in axial positions. The weak donating properties of sulfur atoms are reflected in shortening of the trans-positioned Te–Cl bonds.

Complexes of an azine diphosphine with Group 6 metal carbonyls: crystal structures of Z,Z-PPh2CH2C(But)N–NC(But)CH2PPh2and [Mo(CO)3(E,Z-PPh2CH2C(But)N–N(But)CCH2PPh2)

Treatment of the azine MeC(But)NNC(But)Me with 2 equivalents of LiBun, followed by 2 equivalents of PPh2Cl, gives the azine diphosphine Z,Z-PPh2CH2C(But)N–N(But)CCH2PPh21. This new diphosphine was treated with H2O2 to give the corresponding diphosphine dioxide 2a and with monoclinic sulfur to give the diphosphine disulfide 2b. Treatment of [M(CO)3(η6-cht)](cht = cyclohepta-2,4,6-triene) with 1 gave the metal tricarbonyl fac-[[graphic omitted]Ph2}](M = Mo, 3a; W, 3b; or Cr, 3c) in which the azine diphosphine is bonded in the E,Z configuration. Complexes 3a and 3b were also made by treating the corresponding metal hexacarbonyls with the azine diphosphine 1. Treatment of [M(CO)4(nbd)](M = Mo, W, or Cr; nbd = norbornadiene) with 1 gave the tetracarbonyl complexes [[graphic omitted]Ph2}]4 with the E,Z-azine diphosphine acting as a bidentate ligand. On heating, these tetracarbonyl complexes 4 were converted into the tricarbonyl complexes 3. Treatment of either 3a or 4a with 1 mol equivalent of bromine gave the neutral molybdenum(II) complex [[graphic omitted]Ph2}]5, whereas the tungsten complexes 3b and 4b with bromine gave the cation [[graphic omitted]Ph2}]+ isolated as its BPh4– salt 6. Proton, 13C-{1H} and 31P-{1H} NMR and infrared data are given. Crystals of 1 are monoclinic, space group P21/n, with a= 1667.2(2), b= 572.85(6), c= 1811.0(2) pm, β= 111.595(8)° and Z= 2; final R factor 0.0519 for 2049 observed reflections. Crystals of 3a are monoclinic, space group P21/n, with a= 985.7(1), b= 1870.2(2), c= 2220.8(2) pm, β= 93.71(1)° and Z= 4, final R factor 0.0354 for 5219 observed reflections.

Intermolecular-directed reactivity in solid media. Radiogenic formation of phosphorus-centered radicals in chiral diphosphine disulfides studied by ESR

AWct Singlecrystal, powder, and frozen-matrix ESR experiments have been performed to study the radiogenic electron-capture properties of several diastereoisomeric and asymmetric diphosphine disulfides (R,RzP(S)P(S)R3R4). The principal values of the hyperfine couplings of several phosphorus-centered radical configurations are determined and related to the spin density distribution. Attention is focused on the strong differences in radiogenic properties, observed between the meso and racemic forms of phenyl- and tolyl-substituted diphosphine disulfides. The most striking result is that X irradiation of the crystalline meso compounds MePhP(S)P(S)MePh, Me@-Tol)P(S)P(S)Me@-Tol), and Ph(PhCHz)P(S)P(S)Ph(CH2Ph) does not lead to the formation of a three-electron bond PAP u* radical but invariably results in configurations in which the unpaired electron is primarily localized on one half of the molecule. X irradiation of the corresponding racemic forms, on the other hand, gives rise to PLP u* configurations. The observed discrimination between symmetric and asymmetric configurations is explained in terms of intermolecular steric interactions affecting the geometry relaxation of the precursor molecule after initial electron addition. For a quantitative assessment, the change in van der Waals energy resulting from elongation of the P-P bond of the molecules in their respective crystal lattices was calculated with X-ray crystallographic data. The calculations reveal significantly stronger steric interactions for the aromatic meso compounds than for their racemic forms, in agreement with the absence of PAP u* configurations in the first. X irradiation of diphosphine disulfides in a frozen THF matrix almost invariably results in a single radical product, being the PAP u* configuration, and differences between meso and racemic isomers disappear. This is a consequence of the fact that in a randomly oriented solid matrix the molecular packing is less tight than in a molecular crystal, making more space available to the precursor molecule. It is concluded that in case stabilization of the initial electron adduct via P-P bond length elongation is unfavorable because of steric interactions, other relaxation pathways become accessible, resulting in alternative phosphoranyl radical configurations. In recent years the radiochemistry of organophosphorus compounds has received considerable attention. The phosphoruscentered radicals, formed in the radiation process, are of special interest because of their diverse structural and dynamical prop erties and their possible relevance to radiation damage in biochemical systems.’” It has been shown from a number of single-crystal ESR studies that the precise nature of the configuration of a phosphoranyl radical depends on the type of ligands surrounding the central phosphorus nucleus. Only recently have effects other than the nature of the substituents been envisaged as being essential to the formation of radiogenic phosphoruscentered radicals. In this respect, aspects of conformation and configuration of the precursor molecules and the involvement of the precursor environment in the electron-capture process have been studied.4d Substituted diphosphine disulfides (R,R,P(S)P(S)R,R,) can serve as good probes to study phosphoranyl radical formation because of their intrinsic ability to adopt various radical configurations from a single molecule (Figure l).’ X irradiation of a diphosphine disulfide almost invariably results in the formation of an electron-capture radical in which the unpaired electron is accommodated in the antibonding u* orbital of the inter-phosphorus bond. As a consequence, the electron is symmetrically distributed over the two phosphorus nuclei. Complementary to this symmetrical PAP u* configuration, several radical structures with an asymmetrical spin density distribution have been established. One of the asymmetric structures frequently observed is a radical in which the odd electron is located in the vacant equatorial position of a trigonal-bipyramidal configuration (TBP-e). Another asymmetric structure has been identified as a phosphoranyl radical in which the unpaired electron resides in an antibonding u* orbital of the phosphorussulfur bond (PS U’).

Single Crystal ESR Study of Phosphoranyl Radicals Obtained by Electron Capture of Four-Coordinated Phosphorus Compounds

Abstract x-Irradiation of four-coordinated phosphorus compounds at low temperature yields phosphoranyl radicals formed by electron capture. The structure of these radicals is elucidated at low temperature via single crystal ESR. Analysis of the isotropic and anisotropic contributions to the phosphorus and substituent hyperfine couplings gives an accurate description of the populations (ps and pp) and the directions of the atomic orbitals participating in the single occupied molecular orbital. It is found that radical 1 possesses a deformed trigonal bipyramidal structure with the unpaired electron in an equatorial position (TBP-e) whereas in 2 the unpaired electron resides in an antibonding σ orbital between P and Cl (σ*). For tetrasubstituted diphosphine disulfides (methyl, ethyl and phenyl) a variety of coexisting configurations is established. Structure 3a possesses a symmetrical distribution of the unpaired electron over the two phosphorus atoms (P1 and P2 both 43%). In contrast, an asymmetric spin density distribution is found for radical 3b (P1 49% and P2 29%) and for radical 3c in which the extra electron is found in a σ* P-S orbital.