Ph2PCH2CH2P Ph Research Articles

Seven-coordinate molybdenum(II) carbonyl complexes containing two different bidentate ligands (2,2′-bipyridyl and Ph 2PCH 2PPh 2 or Ph 2PCH 2CH 2PPh 2)

The complexes MoX 2(CO) 3(bipy) (X=Cl, Br, I) undergo substitution of a single CO ligand by Ph 2PCH 2PPh 2 (dppm) and Ph 2PCH 2CH 2PPh 2 (dppe) to give seven-coordinate complexes MoX 2(CO) 2(bipy)(LL) (X=Cl, Br, I; LL=dppm, dppe). Spontaneous isomerization to [MoX(CO) 2(bipy)(dppm)]X was observed for X=I in dichloromethane at room temperature. However MoCl 2(CO) 2(bipy)(dppm) led to MoCl 2(CO)(bipy)(dppm) by sunlight irradiation. The cationic species [MoX(CO) 2(bipy)(LL)]BPh 4 (X=Cl, Br; LL=dppm and X=Cl, Br, I; LL=dppe) were also prepared by use of NaBPh 4. Reactions of MoX 2(CO) 3(bipy) (X=Cl, Br) with dppe in molar ratios 2/1 (complex/ligand) afforded the slightly soluble compounds formulated as dimers, Mo 2X 4(CO) 4(bipy) 2(μ-dppe). We also report the possibility of preparing MoCl 2(CO) 3(bipy) by direct halogenation of Mo(CO) 4(bipy) at room temperature in dichloromethane.

A direct and specific sonochemically assisted preparation of Fe(C 5Me 5)(dppe)X (X = Cl, H)

New Fe(C 5Me 5)L 2X where L 2 = Ph 2PCH 2CH 2PPh 2 (dppe), X = Cl, H, have been prepared by a one-pot reaction from Fe(dppe)Cl 2, C 5Me 5H, and K with activation by 20 kHz ultrasonic radiation. These electron-rich complexes were found to undergo ready one-electron oxidation to give the stable 17-electron species.

Rapid binding and activation of small molecules by [MoH 4(Ph 2PCH 2CH 2PPh 2) 2] in the presence of HBF 4 · OEt 2. Crystal structure of the product obtained with phenylacetylene trans-[MoF(η 2-PhCCH)(Ph 2PCH 2CH 2PPh 2) 2]BF 4

In the presence of HBF 4 · OEt 2, [MoH 4(Ph 2PCH 2CH 2PPh 2) 2] exhibits a remarkably rapid and diverse range of reactions with a variety of small molecules. The crystal structure of the product obtained in the presence of phenylacetylene, trans-[MoF(η 2-PhCCH)(Ph 2PCH 2CH 2PPh 2) 2]BF 4 is reported.

The seven-coordinate hydrido-tantalum complexes [Ta(H)(CO) 6− n(oligophos)]: preparation and dynamics

The hydrido complexes cis-[HTa(CO) 4P 2] (P 2  Ph 2PCH 2CH 2PPh 2), HTa-(CO) 3P m (P m  P 3: PhP(CH 2CH 2PPh 2) 2, P 4: [Ph 2PCH 2CH 2PPhCH 2] 2, PP 3: P(CH 2CH 2PPh 2) 3) have been obtained from the photo-chemically produced complexes [Et 4N][Ta(CO) 4P m ] by ion-exchange chromatography on silica gel. The anionic and neutral complexes have been characterized by IR and 31P and 1H NMR spectroscopy. The temperature-dependent 1H(hydride)- 31P NMR coupling patterns are interpreted in terms of a hydride-capped octahedral structure with restricted migration of the H − ligand between the octahedral faces.

The crystal and molecular structure of [bis(diphenylphosphino)ethane]tricarbonyliron(0)

[Bis(diphenylphosphino)ethane]tricarbonyliron(0), Fe9(CO) 3-(Ph 2PCH 2CH 2-PPh 2), has been prepared by reducing FeCl 2 with metallic manganese under an atmosphere of CO in the presence of the diphosphine at room temperature in THF. The results of an X-ray diffraction study (room temperature, Mo- K α) are: P2 1/ n, a 12.260(6), b 15.890(7), c 14.227(6) Å, β 110.57(3)°, Z = 4, D c 1.378, D m 1.40 Mg m −3, R f ( 2957 413 ) = 0.0393. The iron is pentacoordinate, with a geometry intermediate between trigonal bipyramidal, with a phosphorus and a carbonyl apical, and square pyramidal with a carbonyl alpical. No significant differerences are observed between the FeP distances (av.2.224(2) Å) or between the FeCO distances (av. 1.770(5) Å). Comparison with the analogous bis(diphenylphosphino)methane derivative shows that the main differences in the coordination polyhedra arise from the difference in the P⋯P bite distance, which is 2.981(2) Å in the ethane derivative but only 2.650(3) Å in the methane derivative. The five-membered FePCCP chelate ring shows an unsymmetrical conformation, with one carbon atom tending to lie in the PFeP plane, the corresponding torsion about the FeP bond being almost zero (1.3(2)°). This kind of conformation is common for bis(diphenylphosphino)ethane chelating rings, suggesting a limited flexibility of that ring. The orientations of the phenyl groups are somewhat different from those in the corresponding bis(diphenylphosphino)methane complex.

The formation of alkyne and alkynyl complexes by reaction of 1-alkynes with trans-[M(N 2) 2(PH 2PCH 2CH 2PPh 2) 2] (M  Mo OR W) and with [Mo(Ph 2PCH 2PPh 2) 3]: X-ray structure of trans-[Mo(CCPh) 2(PH 2PCH 2CH 2PPh 2) 2

Reaction of RCCH (R  Ph, CO 2Meor CO 2Et) with trans-[M(N 2) 2(dppe) 2] (M  Mo or W; dppe  Ph 2PCH 2CH 2PPh 2) or [Mo(dppm) 3] (dppm  Ph 2PCH 2PPh 2) gives the alkyne complexes [M(RCCH) 2(diphos) 2] (diphos  dppe, M  Mo, R = Ph; dihpos  dppm, M  Mo, R  Ph or CO 2Me) and the alkynyl complexes trans-[M(cCR) 2(dppe) 2], [MH 2(CCR) 2 (dppe) 2] (M  Mo or W. R  Ph, CO 2Me or CO 2Et) and cis-[WH(CCCO 2Me)(dppe) 2]: the X-ray structure of trans-[Mo(CCPh) 2(dppe) 2] is reported.

31P and 195Pt NMR characteristics of new binuclear complexes of [Pt 2X 4](PR 3) 2] cis/trans isomers and of mononuclear analogs

The 31P and 195Pt chemical shifts are reported for the first time for complexes of binuclear platinum(II) of the type [Pt 2(μ-X) 2(X) 2(PR 3) 2]. These were identified as intermediate from the reaction of the [PtX 2COD)] complex with different tertiary phosphines (where X may be Cl or I and PR 3 may be PBz 3, PCy 3, PCyPh 2, PCy 2Ph or PPh 2C 6F 5). In addition, cis and trans-[PtX 2(PR 3) 2] were produced in the final step, and their 31P and 195Pt are also described (X = Cl or I; PR 3 = PBz 3, PCy 3, PPhCy 2, PPh 2Cy, PPh 2 iPr, PPh 2C 6F 5, PPh 3, P( m-tolyl) 3, P( p-tolyl) 3, PBu 3, PPhMe 2, PPh 2Me, (bis-1,2-Ph 2P)- C 6H 4, Ph 2PCH 2PPh 2 or Ph 2PCH 2CH 2PPh 2). The platinum-195 chemical shift is shown to be relatively sensitive to the nature of complex geometry. The unsymmetrical (unsym.) cis isomer absorbs at a lower frequency (upfield) than the symmetrical (sym.) trans isomer and in a somewhat higher platinum chemical shift than in the equivalent terminal complexes [PtX 2(PR 3) 2], The 1 J(Pt-P) couplings are consistent and related to the cone-angle data of the ligand and the 1 J value of sym. trans form is 1.26 times that for the unsym, cis form and shows some solvent dependency. Interestingly, two isomers of the unsym. cis dimer were identified, and then one of the isomers isomerized to the sym. trans dimer. The nature of the reaction intermediate and products was found to be very dependent on both the reactants and conditions.

Aryl radicals from organometallic sources. Preferential attack on the side chain of toluenes by the o-tolyl radical

The o-tolyl radicals, formed by the reaction of o-chlorotoluene with [Mo(N 2) 2-(dppe) 2] (dppe = Ph 2PCH 2CH 2PPh 2) or by the decomposition of o-toluoyl peroxide, preferentially attack the methyl group of toluenes giving rise to bibenzyls. In contrast the m- and p-tolyl radicals preferentially attack the aromatic nucleus.

Homogeneous reduction of carbon monoxide

Hydride additions to eighteen electron iron cations containing both cyclopentadienyl and carbonyl Ligands occur regioselectively onto coordinated carbon monoxide to generate formyls which undergo further reduction or disproportionate to iron methyls. Alternatively Ligand loss converts the iron formyls to carbonyl hydrides. The carbonyl hydride [(η 5-C 5H 5)Fe(Ph 2PCH 2CH 2PPh 2)(CO)H] exists in equilibrium with the corresponding formyl complex which in polar solvents disproportionates to the methyl complex [(η 5-C 5H 5)Fe(Ph 2PCH 2CH 2PPh 2)CH 3] but in non polar solvents rearranges to the cyclopentadiene complex [(η 4-C 5H 6)Fe(Ph 2PCH 2CH 2PPh 2)CO]. Deuterium labelling studies have shown this latter migration to be an intramolecular transfer of hydride from the iron to the endo-position of the cyclopentadiene. Hydride reduction of the cation [(η 5-C 5H 5)Fe(PMe 3)(CO) 2] +PF 6 − generates via the formyl [(η 5-C 5H 5)Fe(PMe 3)(CO)CHO] the methyl complex [(η 5-C 5H 5)Fe(PMe 3)(CO)CH 3]. Carbon monoxide insertion into this iron methyl generates the corresponding acetyl complex [(η 5-C 5H 5)Fe(PMe 3)(CO)COCH 3] which is reduced by BH 3.THF to the ethyl complex [(η 5-C 5H 5)Fe(PMe 3)(CO)CH 2CH 3]. Successive clean homologations by treatment with CO and BH 3.THF gives after four carbonylations [(η 5-C 5H 5)Fe(PMe 3)(CO)COCH 2CH 2CH 2CH 3] which on oxidation yields entirely CO-derived pentanoic acid. The carbonyl hydride [(η 5-C 5H 5)Fe(PMe 3)(CO)H] in the presence of carbon monoxide produces the cyclopentadiene complex [(η 4-C 5H 6)Fe(PMe 3)(CO) 2] via an intermolecular hydride transfer from an intermediate formyl which is catalysed by [(η 5-C 5H 5)Fe(PMe 3)(CO) 2] +PF 6 −.

(η 5-C 5H 5)(Ph 2PCH 2CH 2PPH 2)RuCH 2+ AsF 6−. Spectral Characterization and measurement of the barrier to methylene rotation

The electrophilic methylene complex (η 5-C 5H 5)(Ph 2PCH 2CH 2PPh 2)RuCH 2 + ( 1) has been characterized by 13C and variable-temperature 1H NMR spectroscopy and exhibits a vertical orientation of the methylene group with a barrier for rotation about the rutheniumcarbon double bond of 10.9 kcal/mol.

The reaction of Co 4(CO) 12 with Ph 2PCH 2CH 2PPh 2. Spectroscopic identification of polymeric products

Co 4(CO) 12 readily undergoes replacement of CO by 1,1-bis(diphenylphosphino)ethane (DPPE) and several derivatives have been characterized. In addition to {[Co 4(CO) 11] 2(μ-DPPE)} (I) and [Co 4(CO) 10(DPPE)] (II), two polymeric products have been identified by IR and 31P NMR spectroscopy. The 13C and 31P variable temperature NMR spectra of I and II are reported.

Untersuchungen zur oxidation des dischwefel-liganden in (η 5-C 5Me 5)M(CO) 2S 2 (M = Mn, Re)

The halfsandwich compounds (Cp *M(CO) 2S 2 (M = Mn or Re) are oxidized by 3-chloro-perbenzoic acid at the disulfur ligand to give disulfur monoxide complexes, Cp *M(CO) 2S 2O 1 1 Abkürzungen: Cp = η 5-cyclopentadienyl, η 5-C 5H 5; Cp * = η 5-pentamethylcyclopentadienyl, η 5-C 5Me 5; diphos = 1,2-Bis(diphenylphosphino)ethan, Ph 2PCH 2CH 2PPh 2. Further oxidation leads to Cp *M(CO) 2S 2O 2. A comparison of the carbonyl stretching frequencies, ν(CO), and derived force constants, k(CO), indicates that sulfur-containing ligands (S 2, SO, SO 2, S 2O, S 2O 2) are stronger electron-withdrawing groups than the ligand cation monoxide, CO. The acceptor capacity increases in the order S 2 < S 2O < S 2O 2.

Preparation of a tetrahydroborate comnplex of rhenium(I), cis-[Re(η 2-BH 4)(Ph 2PCH 2CH 2PPh 2) 2

Dechlorination reactions of the dinitrogen and the isocyanide complexes trans-[ReClL(dppe) 2] (I: L = N 2; II: L = CNMe; dppe = Ph 2PCH 2CH 2PPh 2) by TIBF 4, in the presence of NaBH 4 afford cis[Re(η 2-BH 4)(dppe) 2] (which has a static tetrahydroborate ligand) and the hydride complex trans-[ReH(CNMe)-(dppe) 2], respectively.

Study on the reactions of the dinitrogen complexestrans-[M(N2)2(Ph 2PCH2CH2PPh 2)2] (M=Mo or W) with ethyldiazoacetate: Formation of an Azo compound and of a phosphazene species

Complextrans-[Mo(N2)2(dppe)2] (dppe=Ph2PCH2CH2PPh2) reacts with NN=CHCOOEt in benzene solution to afford benzene-azomethane,Ph-N=N-CH3, as the main organic product. However, the phosphazene speciesPh2P(N2CHCOOEt)(CH2CH2)P(N2CHCOOEt)Ph2 is formed by irradiating aTHF solution oftrans-[W(N2)2(dppe)2] in the presence of ethyldiazoacetate; in moist solution, the phosphazene bonds undergo a partial hydrolysis, and the phosphonium species [Ph2P(NHNCHCOOEt)(CH2CH2)P(NHNCHCOOEt)Ph2]2+ appears to be formed.

Synthesis and spectra of bis(tertiaryphosphine) derivatives of cycloheptatrienyltungsten complexes

Reaction of [WI(CO) 2(η 7-C 7H 7)] with dppm (dppm = Ph 2PCH 2PPh 2) or dppe (dppe = Ph 2PCH 2CH 2PPh 2) gives the trihaptocycloheptatrienyl complexes [WI(CO) 2(L-L)(η 3-C 7H 7)] [L-L = dppm, ( A 1); L-L = dppe ( A 2)]. The complex A 1 reacts with NH 4PF 6 to give the unidentate biphosphine complex [W(CO) 2(dppm-P)(η 7-C 7H 7)][PF 6] ( B) which yields [W(CO)(dppm)(η 7-C 7H 7)][PF 6] ( C) on reaction with Me 3NO·2H 2O. Substitution of a carbonyl ligand in [W(CO) 3(η 7-C 7H 7)][PF 6] with the organometallic phosphine ligand [Mo(CO) 2(dppe-P)(η 7-C 7H 7)][PF 6] yields the heterobimetallic [{W(CO) 2(η 7-C 7H 7)}(μ-dppe){Mo(CO) 2(η 7-C 7H 7)}x][PF 6] 2 ( D).

Mononuclear thiolate complexes of Mo(II) and Mo(III): x-ray crystal structure of trans-[Mo(SBu n) 2(Ph 2PCH 2CH 2PPh 2) 2

The complexes trans-[Mo(SR) 2)(diphos) 2] (A) [R = alkyl, C 6F 5 or C 6H 4X-4, where X = H, F, Cl, CH 3, NH 2 or OCH 3; diphos = Ph 2PCH 2CH 2PPh 2 (dppe) or (C 6H 4CH 3-3) 2PCH 2CH 2P(C 6H 4CH 3-3) 2 (dmtpe)] have been prepared by treatment of trans-[Mo(N 2) 2(diphos) 2] with RSH. trans-[Mo(SBu n ) 2(dppe) 2] crystallizes in the monoclinic space group C2/c with a = 25.605(5) Å, b = 12.055(2) Å, c = 19.637(4) Å, β = 107.08(2)° and final R = 0.041. The molecule is centrosymmetric with Mos = 2.363(1) Å and MoR average = 2.511(1) Å. Compounds ( A) are diamagnetic and the 31P NMR chemical shifts and E ox 1 2 values of ( A, R = C 6H 4X-4) show a linear dependence upon the Hammett σ function for X. Chemical oxidation (FeCl 3 or CuCl 2) followed by anion exchange gives the complexes [Mo(SR) 2(dppe) 2][BPh 4], whose ESR spectra show a rhombic signal in frozen solution having hyperfine splitting which is solvent-dependent.

Synthesis and characterisation of H 3Ru 3Co(CO) 10(dppe) and HRuCo 3(CO) 10(dppe)

Ligand replacement of H 3RU 3Co(CO) 12 and HRuCo 3(CO) 12 by dppe (dppe = Ph 2PCH 2CH 2PPh 2) has been studied. The following crystal structures are reported: (i) H 3Ru 3Co(CO) 1(dppe), orthorhombic, space group Pbca, a 18.609(7), b 19.524(6), c 20.889(5) Å, Z = 8; (ii) HRuCo 3(CO) 10(dppe), monoclinic, space group P2 1/ n, a 15.15(2), b 11.380(4), c 21.792(8) Å, β 98.02(7)°, Z = 4. The phosphorus ligand chelates one Ru atom in H 3Ru 3Co(CO) 10(dppe) and is axially coordinated to two Co atoms in HRuCo 3(CO) 10(dppe). The former complex, unlike the parent cluster H 3Ru 3Co(CO) 12, has two carbonyls bridging RuCo bonds. The molecule contains also the first crystallographically observed edge-bridging Ru(μ-H)Co linkage.

Photochemistry of phosphine hydride complexes of iron group metals

On photolysis cis-[MH 2(DMPE) 2] (M = Fe, Ru; Os; DMPE = Me 2PCH 2CH 2PMe 2) and cis-[MH 2(DPPE) 2] (M = Fe, Ru, Os; DPPE = Ph 2PCH 2CH 2PPh 2) readily lose H 2 by concerted coupling of the two hydrogen atoms. The photoreactions generate the extremely reactive intermediates [M(DMPE) 2] and [M(DPPE) 2] which react with tetracyanoethylene (TCNE) to form metal(II) complexes: [C 2(CN) 3M(DMPE) 2CN], [C 2(CN) 3M(DPPE) 2CN] via free-radical oxidative addition processes. The reactive species may be trapped to give zerovalent compounds upon irradiation of the title compounds in the presence of Lewis ligand L (e.g. [LM(DMPE) 2], [LM(DPPE) 2];L = CO, C 2H 4).

Preliminary communication

Reaction of the terminal alkyne PhCCH with [Mo(NCMe)(dppe)(η 7-C 7H 7)] [PF 6] (dppe = Ph 2PCH 2CH 2PPh 2) in refluxing acetone yields the cationic phenylvinylidene complex [Mo(CCHPh)(dppe)(η 7-C 7H 7)] [PF 6], which is readily deprotonated to give the η 1-alkynyl complex [Mo(η 1-CCPh)(dppe)(η 7-C 7H 7)].

Cationic palladium complexes as highly active catalysts in the telomerization of isoprene with diethylamine

Cationic palladium complexes such as [Pd(dppe)(py) 2][BF 4] 2, dppe = Ph 2PCH 2CH 2PPh 2, are active catalysts for the telomerization of isoprene with diethylamine to give under mild conditions N, N-diethyl(dimethyl-2,7-octadienyl) amines. In contrast to neutral palladium complexes, which favour tail-to-tail coupling of the isoprene units, the head-to-head and tail-to-head linkage prevails with these systems. Experiments with N-deuteriodiethyl-amine revealed that the hydrogen of the nucleophile adds selectively to C-6 of the octadienyl chain, as has been observed earlier for conventional palladium catalysts