Bis phosphino ethane

Submitted by R. CRAIG TAYLOR and DOUGLAS B. WALTERS Checked by E. R. WONCHOBA and G. W. PARSUALLJ 

Although the starting material, tetraethylethylenebis (phospho-nate) is commercially available, its synthesis is reported here. It is possible to prepare this intermediate by a number of different methods 3 5 however, the Arbusov type of rearrangement5 is less time-consuming than the others which have been reported. 

A mixture of 314 g, (1.89 moles) of triethyl phosphitef and 200 g. (1.05 moles) of 1,2-dibromoethane is placed in a two-necked, 500-ml., round-bottomed flask equipped with a thermometer well. The flask is attached to a Nester-Faust 24-in. intermediate-model spinning-band distillation column with a column bore of 8 mm.J The pot temperature is maintained at 145-150°C. After its contents are heated at this temperature for lj-2 hours, ethyl bromide commences to distill. Approximately 130 ml. (180-190 g., 1.6-1.7 moles) of ethyl bromide is collected. After the removal of ethyl bromide is completed, the reaction mixture is cooled to ambient temperature and subsequently fractionated under reduced pressure. The following fractions are obtained  

The product obtained in this fashion is suitable for the next step in the synthesis. 

The following reaction must be carried out under a nitrogen atmosphere. Extreme caution should be exercised during the collection of the product because of its toxic and flammable nature. 

---

Caution. The lithium aluminum hydride reduction step must be carried out in a good hood because of the extreme toxic nature of l,2-bis(phosphino)ethane. The product is spontaneously... 

The synthesis of polyphosphines containing combinations of primary, secondary, and tertiary phosphorus atoms by the base-catalysed addition of P—H across the carbon-carbon double bond of vinyl phosphonates, followed by reduetion with lithium aluminium hydride, has again been described. The preparation of I,2-bis(phosphino)ethane from the bis-phosphonate (17) by reduction with lithium aluminium hydride has been reported in detail. ... 

Preparation of Phosphines by Addition of P-H to Unsaturated Compounds. -This route has not received much attention over the past year. A stereoselective synthesis of tris(Z-styryl)phosphine is offered by the addition of phosphine to phenylacetylene in a superbasic system (HMPA-H20-K0H)." In a similar vein, the reaction of phosphine with styrene and a-methylstyrene in a superbasic medium (DMSO-KOH) provides a route to the primary phosphines, (2-phenylethyl)phosphine and (2-methyl-2-phenylethyl)phosphine, respectively. 7 Transition metal phosphine complexes have been shown to catalyse the a-hydroxylation, P-cyanoethylation, and P-alkoxycarbonylethylation of phosphine. 71 Addition of primary phosphines to acrylic esters has been used for the synthesis of the phosphines (80).7 A similar addition of diphenylphosphine to acrylic esters and amides has given a series of hydrophilic phosphines (81). 72 The bis(phosphorinanyl)ethane (82) is formed in the photochemical addition of l,2-bis(phosphino)ethane to 1,4-pentadiene. ... 

Bisphosphine chiral auxiliaries have been prepared by stereoselective double displacement of a seven-membered cyclic sulfate with 1,2-bis(phosphino)ethane in the presence of n-BuLi (91JA8518) (Scheme 73). Similarly, l,2-bis(phosphino)benzene gave bisphosphine 290 (Scheme 73). These chiral auxiliaries have proved to be powerful ligands in a stereoselective hydrogenation reaction (95JA4423). 

The reaction of the cyclic sulfates 44 of symmetrical anti-l,3-diols and 1,2-bis-(phosphino)ethane yielded 1,2-bis(phosphetano)ethane 45 <01JOM162>. 

Water-soluble iron carbonyl complexes with hydroxyalkyl bis(phosphino)ethane ligands HO(CH2) 2PCH2CFl2-P (CFl2) OH 2 ( = 3, 4) were prepared by addition of CO to the iron(ii) precursor complexes (Equations (73) and (74)). ... 

Technetium-99m tetrafosmin ( Tc-(V)02 (l,2-bis(bis(2-ethoxyethyl)phosphino)ethane) (see Fig. 3d)) is a myocardial perfusion agent. It is used as an adjunct in the diagnosis and localization of myocardial ischemia and/or infarction. 

Abbreviations acac, acetylacetonate Aik, alkyl AN, acetonitrile bpy, 2,2 -bipyridine Bu, butyl cod, 1,5- or 1,4-cyclooctadiene coe, cyclooctene cot, cyclooctatetraene Cp, cyclopentadienyl Cp, pentamethylcyclopenladienyl Cy, cyclohexyl dme, 1,2-dimethoxyethane dpe, bis(diphenyl-phosphino)ethane dppen, cis-l,2-bis(di[Atenylphosphino)ethylene dppm, bis(diphenylphosphino) methane dppp, l,3-bis(diphenylphosphino)propane eda,ethylenediamine Et,ethyl Hal,halide Hpz, pyrazole HPz, variously substituted pyrazoles Hpz, 3,5-dimethylpyrazole Me, methyl Mes, mesityl nbd, notboma-2,5-diene OBor, (lS)-endo-(-)-bomoxy Ph, phenyl phen, LlO-phenanthroline Pr, f opyl py, pyridine pz, pyrazolate Pz, variously substituted pyrazolates pz, 3,5-dimethylpyrazolate solv, solvent tfb, tetrafluorobenzo(5,6]bicyclo(2.2.2]octa-2,5,7-triene (tetrafluorobenzobanelene) THE, tetrahydrofuran tht, tetrahydrothicphene Tol, tolyl. 

Rhodium and ruthenium complexes have also been studied as effective catalysts. Rh(diphos)2Cl [diphos = l,2-bis(diphenyl-phosphino)ethane] catalyzed the electroreduction of C02 in acetonitrile solution.146 Formate was produced at current efficiencies of ca. 20-40% in dry acetonitrile at ca. -1.5 V (versus Ag wire). It was suggested that acetonitrile itself was the source of the hydrogen atom and that formation of the hydride HRh(diphos)2 as an active intermediate was involved. Rh(bpy)3Cl3, which had been used as a catalyst for the two-electron reduction of NAD+ (nicotinamide adenine dinucleotide) to NADH by Wienkamp and Steckhan,147 has also acted as a catalyst for C02 reduction in aqueous solutions (0.1 M TEAP) at -1.1 V versus SCE using Hg, Pb, In, graphite, and n-Ti02 electrodes.148 Formate was the main... 

The only Zr(0) carbonyl complex has been prepared by Wreford and co-workers. When ZrCl4 was treated with l,2-bis(dimethyl-phosphino)ethane (dmpe), and then subsequently reduced with sodium amalgam in the presence of 1,3-butadiene, the dmpe bridged dimer, [(t/-C4H6)2Zr(dmpe)]2(dmpe) (65), resulted (114). The brown crystalline dimer 65 was found to be in equilibrium with the 16-e- coordinatively unsaturated complex, (tj-C4H6)2Zr(dmpe) (66), and free dmpe. When toluene solutions of 65 were exposed to CO at —45°C, 1 equivalent of CO per equivalent of Zr was consumed and the CO adduct (r/-C4H6)2Zr-(dmpe)(CO) (67) precipitated as a yellow solid. If these mixtures were allowed to warm above -22°C under vacuum, the precipitate dissolved and the consumed CO evolved (114). Complex 67 could be isolated by... 

Lehnert and Tuczek further studied end-on terminal coordination by density functional theory (DFT) calculations on the compounds [Mo(N2)2(dppe)2], [MoF(NNH)(dppe)2], and [MoF(NNH2)(dppe)2]+, where dppe= 1,2-bis(diphenyl-phosphino)ethane.50 They proposed a reaction scheme, shown in reaction 6.13, for asymmetric dinitrogen reduction and protonation. The end-on model favored by Lehnert in reference 50, as shown in reaction 6.13, appears to be a less thermodynamically unfavorable pathway, at least to reach the M-NNH3 intermediate. Step 1 produces a metal-attached diazenido ion (NNH-), step 2 produces a hydrazido ion (NNH2 ), and step 3 produces a hydrazidium ion (NNHj). 

Further insight into the carbon-oxygen reductive elimination from Pt(IV) and the involvement of five-coordinate Pt(IV) intermediates has been provided recently. The first direct observation of high-yield C-0 reductive elimination from Pt(IV) was described and studied in detail (50,51). Carbon-oxygen coupling to form methyl carboxylates and methyl aryl ethers was observed upon thermolysis of the Pt(IV) complexes ( P2 )PtMe3(OR) ( P2 =bis(diphenylphosphino)ethane or o-bis(diphenyl-phosphino)benzene OR=carboxylate, aryl oxide). As shown in Scheme 47, competitive C-C reductive elimination to form ethane was also observed. 

Contrary to many of the examples quoted so far, the observed volumes of activation may differ significantly from the expected and could lead to the suggestion of an unexpected mechanism. Basallote and co-workers (38) investigated the substitution of coordinated H2 by MeCN in THF in m s-[FeH(H2)(DPPE)2]+ (DPPE = l,2-bis(diphenyl-phosphino)ethane. The volumes of activation were measured under limiting conditions, i.e., where the observed rate constant is indepen-... 

N4Fi2FegPioS4Ci2gHii6- Iron, tetrakis /i-cyano-( ) -cyclopentadienyl)( 1,2-bis(diphenyl-phosphino) ethane)iron tetra(/i3-thio)tetra-, hexafluorophosphate, 34 164 N4Fe402oP2S4W4C72H4o, Iron,... 

P-Diketonesfrom %/i-epoxy ketones. 2 In the presence of this Pd(0) complex a,/ -epoxy ketones isomerize to /3-dikelones. An added ligand is usually necessary to avoid precipitation of palladium. The most satisfactory adjunct is l,2-bis(diphenyl-phosphino)ethane (dpe). The reaction is conducted in toluene at 80-140° for 10 100 hours. The isomerization is facile with strained epoxides it is sluggish with epoxides bearing an a-alkyl group. 

TRICARBONYL(HYDRIDO) [1,2-BIS(DIPHENYL-PHOSPHINO)ETHANE] MANGANESE AS PRECURSOR TO LABILE SITE DERIVATIVES... 

---