Basic Phosphine Research Articles

Electron-rich, hydrocarbon-metal complexes: Synthesis and oxidation properties of bis(η 3-allyl) iron complexes containing basic phosphines

Methallyl chloride FeCl 2(PR 3) react in the presence of magnesium to give Fe(η 3-2-Me-allyl) 2(PR 3) 2 complexes ( 2b) in good yield [ 2a PMe 3 (70%); 2b PMe 2Ph (80%); 2c P(OMe) 3 (51%)]. Reaction of CH 2C(CH 3)Ch 2M (M = Li, K) with FeCl 2(PR 3) 2/PR 3 gives a mixture of 2 and (trimethylenemethane)Fe(PR 3) 3. Cyclic voltammetry of the complexes 2 shows that oxidation occurs at negative potentials (−0.52 ( 2a), −0.37 V vs. SCE ( 2b)), is irreversible at room temperature, and becomes reversible at low temperature. Complexes 2a, 2b react with an excess of NOBF 4 to give the complexes Fe(No) 2(PR 3) 2.

強親核性トリフェニルホスフィン ｛２，６‐（ＭｅＯ）２Ｃ６Ｈ３｝３Ｐおよび｛２，４，６‐（ＭｅＯ）３Ｃ３Ｈ２｝３Ｐ

General properties of highly basic and nucleophilic tertiary phosphines, tris (2, 6-dimethoxyphenyl) phosphine and tris (2, 4, 6-trimethoxyphenyl) phosphine, are discribed.

Photochemistry of metal—metal bonded complexes

Abstract Complexes op the type (CO) 5 MM′(CO) 3 (α-diimme) (M, M′ = Mn, Re) were photolyzed in 2-Me-THF at 293 K in the absence and presence of PR 3 by irradiation in the low energy M′ → α-diimine charge transfer band. In most cases the primary photoprocess appeared to be homolysis of the (M-M′) metal—metal bond. In the absence of PR 3 the radicals formed react with each other to give M 2 (CO) 10 and M′ 2 (CO) 6 (α-diimine) 2 . It is shown that the stabilities of these M′ 2 (CO) 6 (α-diimine) 2 complexes depend on the α-diimine ligand used. In the presence of PR 3 various reactions are observed, depending on the complex and the PR 3 ligand used. Thus, photolysis of (CO) 5 MnRe(CO) 3 (α-diimine) in the presence of PPh3 or P(n-Bu) 3 gives Mn 2 (CO) 10 and a reaction product of Re 2 (CO) 6 (α-diimine) 2 . However, (CO) 5 MnMn(CO) 3 (α-diimine) in the presence of PPh 3 gives Mn 2 (CO) 8 (PPh 3 ) 2 instead of Mn 2 (CO) 10 . A remarkable reaction is observed when a (CO) 5 MnMn(CO) 3 (α-diimine) complex is photolyzed in the presence of the basic phosphine P(n-Bu) 3 the ionic compound [Mn(CO) 3 (α-diimine)(P(n-Bu) 3 )] + [Mn(CO) 5 ] − being formed as the result of electron transfer from the radical Mn(CO) 3 (α-diimine)(P(n-Bu) 3 ) to Mn(CO) 5 and (CO) 5 MnMn(CO) 3 (α-diimine). This reaction is a photocatalyzed chain reaction with φ ∼ 10. All these reactions involve initial homolysis of the metal—metal bond. Only in the case of (CO) 5 ReMn(CO) 3 (R-DAB) in the presence of PR 3 was a carbonyl group of the Mn(CO) 3 (R-DAB) fragment photosubstituted. The mechanisms of the reactions are discussed.

Tetraborane(8) adducts of strongly basic phosphines

Abstract : Four methods were developed for the preparation of B4H8.P(CH3)3. the removal of one of thhe trimethylphosphine ligands from B4H8.2P(CH3)3 by B2H6, the hydride removal from B4H9P(CCH3)3byB2H6, the boron framework expansion of B3H7THF with the use of B2H42P(CH3)3 and the reaction of B3H62P(CH3)3B3H8- with trimethylamine. The yields were better than 90%. The adduct of tris(dimethylamino)phosphine, B4H8.P(N(CH3)2)3 was prepared from the above mono(phoshine)adducts. These were B4H8P(N(CH3)3N(CH3)3N(CH3)3, and B4H8P(CH3) 3P(N(CH3)2)3. The former existed in two isometric forms, each being different from the other in the positions of the two different ligands. These compounds were characterized by their 11B1H, and 31P NMR spectra. Originator-supplied keywords include: Boranes, Phoshines, Lewis Bases.

Zwitterionic adducts from trialkylphosphine and (η-allyl)dicarbonyl-nitrosyliron complexes: structure and reactivity

The reaction between [Fe(η-C3H5)(CO)2(NO)] and strong basic phosphine ligands L [PMe3, PEt3, PBun3, or P(C6H11)3] in organic solvents (benzene or diethyl ether) gives the zwitterionic adducts [Fe(η2-CH2 CHCH2PR3)(CO)2(NO)]. The structure has been assigned on the basis of i.r. and n.m.r. spectra and conductivity measurements. The reactivity and the decomposition mechanism are discussed.

Ethanol from H 2 and CO via homogeneous ruthenium catalysis

Ruthenium carbonyl complexes in the presence of an iodide promoter, an acid, and a phosphine oxide provide an unusually selective catalytic system for the direct conversion of CO and H 2 to ethanol. Reaction conditions studied range from 30 to 87 MPa and 180 to 250 °C (1 MPa = 9.87 atm). Other products include methanol, methane, acetaldehyde, ethylene glycol, and n-propanol. Much of the ethanol may be derived from initially formed methanol, and the acid component appears to be necessary to facilitate this homologation process. The basic phosphine oxide solvent levels the acidity of the solution, preventing a strong acid from protonating and destroying basic metal complexes involved in the CO hydrogenation process.

Co-dimerisation of 1,3-dienes and acrylic esters catalysed by cationic allylpalladium complexes: the role of phosphines

Basic phosphines, especially tributylphosphine, when added in 1 : 1 ratio to cationic allylpalladium complexes, allow the selective co-dimerisation of 1,3-dienes and acrylic esters to linear, unsaturated esters, presumably owing to the inducement of an η3–η1 shift of the allyl ligands by the phosphines.

The basicity of phosphines

The basicities of the triarylphosphines P(4-XC6H4)3 (X = Cl, F, H, CH3, CH3O, (CH3)2N), P(3-CH3C6H4)3, and P(2-CH3C6H7)3 as well as the trialkylphosphines P(t-Bu)3 and PCy3 have been measured by the nitromethane titration method. The range of basicity available by aryl substitution is very large, being pKa = 8.65 for X = (CH3)2N to 1.03 for X = Cl. The most basic phosphine is P(t-Bu)3 whose pKa = 11.40. The measured basicities correlate well with σp, [Formula: see text], and ν as well as with the lone pair ionisation potentials of the triarylphosphines. Generally the 1H, 31P, and 13C nmr spectral parameters of the free and protonated phosphines do not correlate well with pKa.

Ethylene displacement reactions of h 5-indenylbis- (ethylene)rhodium(I)

The barrier to ethylene rotation in h 5-indenylbis(ethylene)rhodium I is lower than that in the analogous h 5-cyclopentadienyl complex and ethylene is readily displaced by carbon monoxide, fluorophosphines and also by more basic phosphines to form Rh(h 5-C 9H 7)L 2 complexes. Unhindered dienes also displace ethylene from I. Several mixed ligand complexes of the type Rh(h 5-C 9H 7)LL′ (L = phosphine or CO) are also reported and possible mechanisms of ethylene displacement are discussed.

Reaction d′homocouplage du type kharasch catalysee par des complexes du fer

The homocoupling reaction between phenylmagnesium bromide and benzyl chloride is selectively catalysed by CpL2FeX (L = PMe2Ph or1/2 DMPE, X = Br or Ph). The selectivity of the reaction is related to the presence of basic phosphines on the transition metal. The reaction does not occur with aromatic halides. We propose a catalytic cycle for this reaction with one-electron transfer processes between iron complexes, containing in some cases an iron—-magnesium bond, and benzyl halide. Les complexes CpL2FeX (L = PMe2Ph ou1/2DMPE, X = Br ou Ph) catalysent sélectivement la réaction d′homocouplage mettant en jeu le bromure de phénylmagnésium et le chlorure de benzyle. La sé1ectivitéde la réaction est liéeála présence de phosphines basiques sur le métal de transition. La réaction n′a pas lieu lorsque le dérivéhalogénéest aromatique. Il est probable que le cycle catalytique de cette réaction d′homocouplage fait intervenir des processus radicalaires par transleft d′unélectron entre des complexes comportant dans certains cas une liaison fer—-magnésium et le dérivéhalogénébenzylique.

Synthesis, characterization and halogenation of some dihydroboron(1+) salts containing phosphine bases

Several dihydroboron(1+) cations of the types LYBH2+ and YY′BH2+ in which L is an amine, Y is a phosphine, and Y′ is a different phosphine were synthesized and characterized. A cyclic dihydroboron(1+) salt containing 1,2-bis(diphenylphosphino)ethane was also prepared and characterized. The PF6− salts and their chlorination products were studied via proton and boron NMR and IR data. Several asymmetric cations of the types LYBHCl+ and YY′BHCl+ are reported. The bound phosphine P(CH3)2C6H5 was found to have nonequivalent methyl resonances in the proton NMR spectra of the cations [(CH3)3NBHClP(CH3)2C6H5]+ and [(C6H5)3PBHClP(CH3)2C6H5]+ which confirms the asymmetric nature of the boron atoms in these two cations.

Metallorganische diazoalkane : XIII. Reaktionen metallorganischer diazoalkane mit P(NMe 2) 3 zu metallorganischen phosphazinen L nM(R)CNNP(NMe 2) 3

Staudinger reactions of 20 organometallic diazoalkanes and of their parent compounds CH 2N 2, HC(N 2)CO 2Et, HC(N 2)C(O)Me and HC(N 2)C(O)Ph with a strong basic phosphine P(NMe 2) 3 are described and were classified into five groups 1–5 of different reactivity. Mono-diazomethanes L n MCHN 2 (for L n M = Me 3Si, Me 2As) react to give ( cis, trans) isomers of the corresponding phosphazines L n MC(H)NNP(NMe 2) 3; a stepwise reaction of functional diazogroups in organometallic bis-diazoalkanes, e.g. Hg[C(N 2)CO 2Et] 2, has been observed. Different reactivity of organometallic diazoalkanes cannot be rationalized by known spectroscopic data but can be interpreted by steric effects. In analogy to reactions of isoelectronic azides a transition state of the Staudinger reaction is suggested with an attack of the basic phosphine at the electrophilic α-nitrogen atom and following rearrangement into the N β-Staudinger adduct. Trimethylgermaniumdiazomethane, Me 3GeCHN 2, was obtained as a novel monosubstituted organometallic diazoalkane and is fully characterized.

The organothio-bridged derivatives of iron carbonyl. II. The dynamic nuclear magnetic resonance study of the anti-syn isomerism in bis(μ-tertiarybutylsulphido)hexacarbonyldiiron and its monosubstituted products with some phosphines and phosphites: an unusually fast interconversion rate

The anti-syn interconversion rate of (μ-Bu tS) 2Fe 2(CO) 6 is about one thousand times faster than that of the other alkyl and aryl derivatives and becomes fast in the NMR time scale at temperatures above 90 °C. The coalescence temperature of the Bu t signals is lowered by substitution of a carbonyl group with a phosphorus ligand and a single sharp resonance is observed at room temperature with the more basic phosphines The mechanism of inversion at sulphur is discussed in connection with related systems. Not all monosubstituted products are stable in solution and their tendency to release the coordinated phosphine increases with the bulkiness of the ligand.

Cyanoalkyl Complexes of Platinum (II). I. Preparation and Spectroscopic Properties

AbstractThe oxidative addition of XRCN to PtL4 yields cis‐and/or trans‐PtX(RCN)L2 (X = Cl, Br; R = (CH2)n, n = 1, 2, 3; L = PPh3, PPh2CH3, AsPh3). L is readily displaced by more basic phosphines or by a diphosphine. In each case the trans complex is the thermodynamically more stable isomer and cis‐trans isomerization catalyzed by free L occurs in dichloromethane. Insertion of CO in the σ PtC bond takes place quantitatively in the case of cyanoethyl and cyanopropyl. Abstraction of X by AgBF4 gives cis or trans cationic complexes with N‐bonded CN group.

74. The stereochemistry of organic derivatives of phosphorus. Part I. The synthesis of acidic and basic dissymmetric tertiary phosphines. The optical resolution of phenyl-p-(carboxymethoxy)phenyl-n-butylphosphine sulphide

74. The stereochemistry of organic derivatives of phosphorus. Part I. The synthesis of acidic and basic dissymmetric tertiary phosphines. The optical resolution of phenyl-p-(carboxymethoxy)phenyl-n-butylphosphine sulphide