Phosphane Selenides Research Articles

Synthesis, Coordination and Electrochemistry of a Ferrocenyl‐Tagged Aminobisphosphane Ligand

AbstractIntroducing a ferrocene moiety into a molecule results in the incorporation of a metal center and a redox active moiety. This contribution describes the synthesis of FcN(CH2PPh2)2 (1; Fc=ferrocenyl), a ferrocene analog of the widely studied bis‐phosphane pincer ligands, RN(CH2PPh2)2. Compound 1 was studied as a ligand in complexes of Group 10 and 11 metal ions. The following compounds were synthesized and characterized using a combination of spectroscopic methods and single‐crystal X‐ray diffraction analysis: the square planar complexes [MX2(1‐κ2P,P’)] (M/X=Ni/Cl, Pd/Cl, Pd/Br, Pd/I and Pt/Cl) and the tetrahedral complexes [M(1‐κ2P,P’)2]X (M/X=Cu/PF6, Ag/SbF6 and Au/SbF6). Furthermore, a pair of open and cyclic digold(I) complexes containing bis‐phosphane 1 as a P,P‐bridging ligand, viz. [(μ(P,P’)‐1)(AuCl)2] and [(μ(P,P’)‐1)2Au2][SbF6]2, were isolated. Ligand 1, the corresponding phosphane selenide 1‐Se and all complexes (except for the poorly soluble [(μ(P,P’)‐1)2Au2][SbF6] and unstable [Ag(1‐κ2P,P’)2][SbF6]) were further analyzed by cyclic voltammetry.

Steric and electronic evaluations of P(o-tol)R2, where R is phenyl or cyclohexyl: crystal structures of SeP(o-tol)R2.

The crystal structures of SeP(o-tol)R2, where o-tol is ortho-tolyl (2-methylphenyl) and R is Ph (phenyl), namely (2-methylphenyl)diphenylphosphane selenide, C19H17PSe, or Cy (cyclohexyl), namely dicyclohexyl(2-methylphenyl)phosphane selenide, C19H29PSe, were determined to aid in the evaluation of the steric and electronic behaviour of these analogous phosphane compounds. The compounds crystallized in similar monoclinic crystal systems, but are differentiated in their unit cells by a doubling of the number of independent molecules for R= Cy (Z'= 2) and the choice of glide plane by convention. The preferred orientation for the o-tolyl substituent obtained from the X-ray structural analysis is gauche for R= Ph and anti for R= Cy (using the Se-P-Cipso-Cortho torsion angles as reference). Density functional theory (DFT) calculations showed both conformations to be equally probable and indicate that the preferred solid-state conformer is probably due to the minimization of repulsion energies, resulting in a packing arrangement primarily featuring weak C-H...Se interactions and additional C-H...π interactions in the R= Ph structure. A detailed electronic and steric analysis was conducted on both phosphanes using Se-P bond lengths, multinuclear NMR 1JSe-P coupling constants, theoretical topological evaluation and crystallographic and solid-angle calculations, and compared to selected literature examples. The results indicate that the use of the o-tolyl substituent increases both the electron-donating capability and the steric size, but is also dependent on whether the o-tolyl group adopts a gauche or anti conformation. The single-crystal geometrical data are unable to detect electronic differences between these two structures due to the somewhat large displacement parameters observed for the Se atom in the R= Cy structure.

Highly Functionalized Brønsted Acidic/Lewis Basic Hybrid Ferrocene Ligands: Synthesis and Coordination Chemistry

A general challenging issue in the synthesis of hemilabile ferrocene ligands is the access to highly functionalized ferrocene starting materials. These can bear donor/acceptor atoms, additional functional and structuring spectator substituents, but the preparation of such species poses general synthetic difficulties. We report herein alternative synthetic routes to hybrid ferrocene donors such as tert‐butylated phosphanylcarboxylic acids and their corresponding aldehydes. These hybrid ambiphilic species that combine Brønsted‐acidic and Lewis‐basic functional moieties in their structure were characterized by multinuclear NMR and single‐crystal X‐ray diffraction analysis. In the solid state, the mutual arrangement of functional groups at the ferrocene unit is highly dependent on hydrogen bonding interactions despite the structural hindering effect of the tert‐butyl groups introduced. The ligands were converted to gold(I) complexes and phosphane selenides to further monitor the properties and mutual influence of the functional groups in the prepared compounds.

Chlorination of Phosphane Selenides

AbstractChlorination of the phosphane selenide iPrtBu2PSe with PhICl2 leads to the compound iPrtBu2PSe2Cl2, which contains a P–Se–SeCl2 moiety and is formally a phosphane selenide complex of selenium dichloride. Two polymorphs of the product were identified by X‐ray structure analysis. The analogous reaction with tBu3PSe gave an oil, presumably tBu3PSe2Cl2, from which small quantities of tBu3PSe3Cl2 were obtained and characterized by X‐ray structure analysis.

A Simple Approach to Vicinal Pyrrolylphosphane Aldehydes

ABSTRACTA simple approach to vicinal pyrrolylphosphane aldehydes was developed. The reaction of Alder's dimer 1 with a set of pyrrolylphosphane derivatives—its oxides, sulfides, and selenides—was studied in detail. While Alder's dimer reacted with phosphane oxides and sulfides at the O and S atoms, phosphane selenides 4a–c were found to be suitable for the introduction of the formyl group into the pyrrole ring. The reaction of highly electrophilic Alder's dimer with pyrrolylphosphane selenides proceeded predominantly at the pyrrolyl nuclei, affording the corresponding aldehydes. The phosphoroselenoyl groups of aldehydes 11 were reduced either with Raney Ni or hexamethylphosphorustriamide under mild conditions, affording pyrrolylphosphane aldehydes 12.

Facile Synthesis of Hyper‐Branched Tetraphosphanes and Tetraphosphane Chalcogenides

AbstractNovel families of hyper‐branched tertiary tetraphosphanes, tetraphosphane sulfides, and tetraphosphane selenides were synthesized in 72–97 % yield by treating secondary phosphanes, phosphane sulfides, and phosphane selenides with the tetravinyl ether of pentaerythritol (UV irradiation, room temp. or AIBN, 65 °C). (© Wiley‐VCH Verlag GmbH & Co. KGaA, 69451 Weinheim, Germany, 2009)

Palladiumdichloride (ferrocenylethynyl)phosphanes and their use in Pd-catalyzed Heck–Mizoroki- and Suzuki–Miyaura carbon–carbon cross-coupling reactions

In this work the synthesis of phosphane selenides (FcC C) n Ph 3− n P Se ( 2a, n = 1; 2b, n = 2; 2c, n = 3; Fc = ferrocenyl, (η 5-C 5H 4)(η 5-C 5H 5)Fe) from (FcC C) n Ph 3− n P ( 1a, n = 1; 1b, n = 2; 1c, n = 3) and selenium is described to estimate the σ-donor properties of these systems by 31P{ 1H} NMR spectroscopy. Progressive replacement of phenyl by ferrocenylethynyl causes a shielding of the phosphorus atom with increasing of the 1 J( 31P– 77Se) coupling constants. The palladiumdichloride metal-organic complexes [((FcC C) n Ph 3− n P) 2PdCl 2] ( 3a, n = 1; 3b, n = 2; 3c, n = 3) have been used as (pre)catalysts in the Suzuki–Miyaura (reaction of 2-bromo-toluene ( 4a) and 4-bromo-acetophenone ( 4b), respectively, with phenyl boronic acid ( 5) to give 2-methyl biphenyl ( 6a) and 4-acetyl biphenyl ( 6b)) and in the Heck–Mizoroki reaction (treatment of iodobenzene ( 7) with tert-butyl acrylate ( 8) to give E- tert-butyl cinnamate ( 9)). The structures of molecules 1a, 1c, 2c, and 3c in the solid state were determined by single X-ray structure analysis showing that the structural parameters of these systems are unexceptional and correspond to those of related phosphanes, seleno phosphanes, and palladium dichloride complexes.

Non-Catalyzed, Atom-Economic, High-Yield Synthesis of Tertiary α-Hydroxyphosphane Selenides

First examples of a facile hydroselenophosphorylation of aldehydes are reported. Nucleophilic addition of P,Se-ambident secondary phosphane selenides to a series of aldehydes proceeds under catalyst-free conditions at room temperature to give tertiary α-hydroxyphosphane selenides in high yield.

Synthesis and Characterization of Three Coordinate “T-Shaped” Complexes of Tellurium (II) Incorporating a Naphthyl Tellurium Fragment

Several new three coordinate tellurium(II) complexes have been prepared by the addition of dinaphthyl ditelluride (C10H7)2Te2 and a halogen (Br2 or I2) to various monodentate ligands known to coordinate through their terminal sulfur or selenium atoms to investigate possible electronic and steric effects associated with a large aryl group. Complexes of the type RTeX(L) are described here [R = naphthyl, X = Br, I, L = thiourea (I (X = Br), II (X = I)), tetramethylthiourea (III), selenourea (IV), tris(dimethylamino)phosphane selenide (V) and N-methylbenzothiazol-2(3H)-thione (VI)]. Evidence of the formation of new complexes is presented through microanalytical data and multinuclear NMR spectroscopy in addition to single crystal X-ray diffraction studies of (I) and (III). Structures are described in detail along with a comparison with related Te (II) complexes.

Complexes of Bidentate Phosphane Selenide Ligands with Mesitylenetellurenyl Iodide and with Tellurium Diiodide

AbstractBis(diphenylphosphanyl)methane diselenide (dppmSe2, 1) and bis(diphenylphosphanyl)ethane diselenide (dppeSe2, 2) reacted with 2 equiv. Br2 or I2 to form the insoluble solid products, dppm(SeX2)2 (X = Br, 3; X = I, 4) and dppe(SeX2)2 (X = Br, 5; X = I, 6). However, using the iodine‐like electrophile mesitylenetellurenyl iodide (MesTeI, 7), fairly soluble complexes, dppmSe2[Te(I)Mes]2 (8) and dppeSe2[Te(I)Mes]2 (9), were obtained. Complexes 8 and 9 contain two T‐shaped (10‐Te‐3) Se–Te(Mes)–I moieties bridged by dppm or dppe; solid 9 exhibits intermolecular soft–soft interactions between approximately linear Se–Te–I units. In a side reaction accompanying the crystallisation of complex 8, or by the reaction of 1 with Te and I2, a chelate complex dppmSe2TeI2 (10) was formed. Fortuitously, a crystal of the related compound dppeSe2TeI2 (11) was also obtained. In 10, a square planar cis‐Se2TeI2 group is part of a six‐membered ring, and 11 is a coordination polymer with trans‐Se2TeI2 moieties bridged by dppe. Averaged 31P‐ and 77Se NMR signals including 77Se–31P couplings, together with broad 125Te NMR singlets indicate phosphane selenide ligand exchange in solution, that is, the kinetically labile behaviour of complexes 8 and 9. (© Wiley‐VCH Verlag GmbH & Co. KGaA, 69451 Weinheim, Germany, 2006)

The Bromination of Bulky Trialkylphosphane Selenides R2R′PSe (R, R′ = iPr or tBu) Studied by Physical and Computational Methods

AbstractBulky trialkylphosphane selenides tBu3PSe (1a), iPr3PSe (1b), tBu2(iPr)PSe (1c) and tBu(iPr)2PSe (1d) react with one equiv. of bromine providing “T‐shaped” products R2R′P–SeBr2 (2a–d), which contain three‐coordinate selenium atoms (10‐Se‐3). The solid compounds 2b (bimorphic), 2c and 2d exhibit different extents of distortions of the PSeBr2 moieties and different patterns of intermolecular soft–soft interactions. In mixtures containing 1 and 2, exemplified by the “NMR‐titration” of 1c with molecular bromine, averaged 31P NMR singlets and their 77Se satellites indicate rapid intermolecular bromine exchange reactions (kinetic lability of the Se–Br bonds). Calculations modelling such bromine transfer support nucleophilic attack of R3PSe (Se → Br) on an electrophilic Br atom of R3PSeBr2. Among the phosphane selenides 1a–d, tBu(iPr)2PSe (1d) gives the largest 77Se NMR upfield shift and tBu2(iPr)PSe (1c) the lowest, that is, 77Se NMR shifts do not correlate with increasing numbers of tert‐butyl groups. GIAO‐HF/962+(d) calculations on the 77Se NMR shifts of compounds 1 allow correlation of surprising relative deshielding of 1c, compared with 1b and 1d, with its particular population of rotamers (excluding a rotamer with anti arrangement of the SePCH moiety in 1c). Bromine addition to compounds 1 leads to line broadening and extreme deshielding in the 77Se NMR spectroscopy. Reaction of 2b with bromine leads – inter alia – to P–Se cleavage with P‐bromination. The structures of 1b, 2b–d and tBu2(iPr)PBr2 (3c) were determined by X‐ray crystallography. In compounds 2b–d, intramolecular C–H···Br interactions determine the conformation to a large extent. (© Wiley‐VCH Verlag GmbH & Co. KGaA, 69451 Weinheim, Germany, 2006)

Phosphane‐Substituted Selenido‐(carbonyl)iron and ‐(carbonyl)ruthenium Clusters: Structures, Fluxionality and Reactivity

AbstractFor Abstract see ChemInform Abstract in Full Text.

Phosphane‐Substituted Selenido−(carbonyl)iron and −(carbonyl)ruthenium Clusters: Structures, Fluxionality and Reactivity

AbstractSelenium‐transfer reactions from tertiary phosphane and diphosphane selenides to the carbonyl clusters [M3(CO)12] (M = Fe or Ru) provide a simple, stepwise synthetic route to phosphane‐substituted, mono‐ and diselenido−(carbonyl)iron and −(carbonyl)ruthenium clusters. Four families of clusters are generally obtained: (i) the M2Se2L6 tetrahedral species (only for iron), (ii) the M3SeL10 capped triangular species, (iii) the M3Se2L9 square‐pyramidal nido species (for iron and ruthenium), and (iv) the M4Se2L11 octahedral closo species (only for ruthenium), with L being a phosphane or carbonyl ligand. When the tertiary phosphane selenide contains heterocyclic fragments, the reaction is not only limited to the transfer of the selenium atom, but proceeds by P−C and, sometimes, C−H bond cleavages, affording new selenido‐phosphido carbonyl clusters bearing coordinated heterocyclic fragments. Many clusters show fluxional behaviour in solution because of either ligand mobility or M−M bond migration. Furthermore, dimetallic substituted carbonyl clusters have been prepared by two different synthetic approaches: (1) MM′ + PSe (reactions between preformed dimetallic clusters and tertiary phosphane selenides) and (2) MSeP + M′ [cluster growth reactions from preformed chalcogenido− (carbonyl)metal clusters and suitable organometallic fragments]. In particular, from the tetrahedral clusters [HMCo3(CO)12] (M = Fe or Ru) monoselenido clusters [MCo2(μ3‐Se)] with a tetrahedral core have been obtained. The second type of approach has been applied to the open‐triangular nido clusters [Ru3(μ3‐Se)2(CO)9−nLn] (L = tertiary phosphane, n = 1 or 2), which can add zero‐s.e.p.’s organometallic fragments, such as M(CO)3 (M = Mo or W), giving the corresponding closo clusters [MRu3(µ4‐Se)2(CO)12−nLn]. (© Wiley‐VCH Verlag GmbH & Co. KGaA, 69451 Weinheim, Germany, 2003)

Preparation, Properties, and Reactions of Metal‐Containing Heterocycles, XCV. Transition‐Metal‐Mediated Cyclocotrimerization of Selenophosphinites with Activated Alkynes

AbstractSelenophosphinito complexes (OC)4Mn(η2‐Se\documentclass{article}\usepackage{amsmath}\pagestyle{empty}\begin{document}$ \dddot - $\end{document}PR21) (2a, b) [R1 = cyc‐Hex (a), tBu (b)] are formed by the reaction of BrMn(CO)5 with the phosphane selenides R21HPSe (1a, b) in the presence of the auxiliary base Et(iPr)2N. According to an X‐ray structural analysis, 2a crystallizes in the space group \documentclass{article}\pagestyle{empty}\begin{document}$ P\bar 1 $\end{document} with Z = 2. The dimeric complex [(OC)4Mn(μ‐Se\documentclass{article}\usepackage{amsmath}\pagestyle{empty}\begin{document}$ \dddot - $\end{document}PMe2)]2 (4c) is not obtained in a straightforward way. Compound 4c is only obtained via the intermediate Br(OC)4Mn–Se\documentclass{article}\usepackage{amsmath}\pagestyle{empty}\begin{document}$ \dddot - $\end{document}P(H)Me2 (3c) by HBr elimination with nBuLi. Complex 3c is formed by replacement of carbon monoxide in BrMn(CO)5 by Me2HPSe (1c). A dissociative equilibrium between [(OC)4 Mn(μ‐Se\documentclass{article}\usepackage{amsmath}\pagestyle{empty}\begin{document}$ \dddot - $\end{document}PMe2)]2 (4c) and the monomeric species (OC)4Mn(\documentclass{article}\usepackage{amsmath}\pagestyle{empty}\begin{document}$ \dddot - $\end{document}2‐Se\documentclass{article}\usepackage{amsmath}\pagestyle{empty}\begin{document}$ \dddot - $\end{document}PMe2) was not observed. The cyclocotrimerization of the >P\documentclass{article}\usepackage{amsmath}\pagestyle{empty}\begin{document}$ \dddot - $\end{document}Se function with the activated alkynes ZCCZ [Z = CO2R2; R2 = Me (d), Et (e), iPr (f), cyc‐Hex (g)] was successful only in the case of the cyclohexyl derivative 2a to give the selenaphosphamanganabicycloheptadienes 5d – g. An X‐ray structural analysis proved that 5d crystallizes in the space group \documentclass{article}\pagestyle{empty}\begin{document}$ P\bar 1 $\end{document} with Z = 2. Under CO pressure 5d was degraded to the selenophene 6.

Bismuth(III) complexes with sulfur and selenium donor ligands: synthesis and crystal structures of BiCl3·Prn2P(S)P(S)Prn2and [(Me2N)3PSeSeP(NMe2)3]2+[(BiCl4)2]n2n–

Direct addition of bismuth(III) chloride and tetra-n-propyldiphosphane disulfide gave bright yellow crystals of the 1 : 1 adduct BiCl3·Prn2P(S)P(S)Prn2. An X-ray crystallographic investigation reveals a halide-bridged dimeric structure in which each bismuth atom is surrounded by an essentially octahedral arrangement of four chlorine [two terminal. Bi–Cl 2.500(5), 2.516(5), and two bridging, Bi–Cl 2.653(4). 3.015(5)Å] and two sulfur atoms [Bi–S 2.857(4), 2.973(4)Å]. Each of the two ligand molecules is involved in bidentate (S,S′) chelation to a bismuth atom to form a five-membered ring. Crystals are monoclinic, space group P21n, with a= 10.127(6), b= 16.057(6), c= 13.843(6)Å, β= 93.3(1)°, Z= 4. The reaction of BiCl3and tris(dimethylamino)phosphane selenide in acetonitrile gave the yellow crystalline salt [(Me2N)3PSeSeP(NMe2)3]2+[(BiCl4)2]n2n– as identified by a crystal structure determination. Formation of the unusual cation follows from air oxidation of the organophosphine selenide in the presence of BiCl3. The Se–Se bond distance is 2.309(5)Å and the torsion angle P–Se–Se–P is –112.4(4)°. For the anion, linkage of dimeric (BiCl4)2 units via further halide bridging results in an infinite chain structure of edge-shared octahedra. Crystals are triclinic, space group P with a= 7.386(6), b= 12.813(8), c = 18.919(8)Å, α= 76.0(1 ), β= 78.9(1 ), γ= 73.2(1)° and Z= 2.

31P solid state nuclear magnetic resonance principal values of the chemical shift tensors of phosphane oxides, phosphane sulphides and phosphane selenides

The principal components of the 31P chemical shift tensor of sixteen phosphane oxides (O=PR 3), phosphane sulphides (S=PR 3) and phosphane selenides (Se=PR 3) have been determined for powder samples using the proton enhanced nuclear induction technique. The chemical shift anisotropy is comparable or larger than the 31P chemical shift difference observed in the liquid state by change of coordination or functionality around the phosphorus. For a given group R, the chemical shift anisotropy is larger for the oxide than for the sulphide or selenide. The electronic distribution around the phosphorus parallels the 31P chemical shift anisotropy. A linear variation of the asymmetry parameter with the departure from C 3 symmetry around the phosphorus is observed.