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1.
Bis(ferrocenyl)-substituted allenylidene complexes, [(CO)5MCCCFc2] (1a-c, Fc = (C5H4)Fe(C5H5), M = Cr (a), Mo (b), W (c)) were obtained by sequential reaction of Fc2CO with Me3Si-CCH, KF/MeOH, n-BuLi, and [(CO)5M(THF)]. For the synthesis of related mono(ferrocenyl)allenylidene chromium complexes, [(CO)5CrCCC(Fc)R] (R = Ph, NMe2), three different routes were developed: (a) reaction of the deprotonated propargylic alcohol HCCC(Fc)(Ph)OH with [(CO)5Cr(THF)] followed by desoxygenation with Cl2CO, (b) Lewis acid induced alcohol elimination from alkenyl(alkoxy)carbene complexes, [(CO)5CrC(OR)CHC(NMe2)Fc], and (c) replacement of OMe in [(CO)5CrCCC(OMe)NMe2] by Fc. Complex 1a was also formed when the mono(ferrocenyl)allenylidene complex [(CO)5CrCCC(Fc)NMe2] was treated first with Li[Fc] and the resulting adduct then with SiO2. The replacement route (c) was also applied to the synthesis of an allenylidene complex (7a) with a CC spacer in between the ferrocenyl unit and Cγ of the allenylidene ligand, [(CO)5CrCCC(NMe2)-CCFc]. The related complex containing a CHCH spacer (9a) was prepared by condensation of [(CO)5CrCCC(Me)NMe2] with formylferrocene in the presence of NEt3. The bis(ferrocenyl)-substituted allenylidene complexes 1a-c added HNMe2 across the Cα-Cβ bond to give alkenyl(dimethylamino)carbene complexes and reacted with diethylaminopropyne by regioselective insertion of the CC bond into the Cβ-Cγ bond to afford alkenyl(diethylamino)allenylidene complexes, [(CO)5MCCC(NEt2)CMeCFc2]. The structures of 5a, 7a, and 9a were established by X-ray diffraction studies. 相似文献
2.
Normen Szesni 《Inorganica chimica acta》2005,358(5):1645-1656
The aminoallenylidene(pentacarbonyl)chromium complexes [(CO)5CrCCC(NR1R2)Ph] (1a-c) react with dimethylamine by addition of the amine to the C1C2 bond of the allenylidene ligand to give alkenyl(amino)carbene complexes [(CO)5CrC(NMe2)CHC(NR1R2)Ph] (2a-c) (R1 = Me: R2 = Me (a), Ph (b); R1 = Et: R2 = Ph (c)). In contrast, addition of a large excess (usually 20 equivalents) of ammonia or primary amines, H2NR, to solutions of [(CO)5CrCCC(NMe2)Ph] (1a) affords the aminoallenylidene complexes [(CO)5CrCCC(NHR)Ph] (1d-w) in which the dimethylamino group is replaced by NH2 or NHR, respectively. In addition to simple amines such as methylamine, butylamine, and aniline, amines carrying a functional group (allylamine, propargylamine) and amino acid esters as well as amino terpenes and amino sugars can be used to displace the NMe2 substituent. Usually the Z isomer (with respect to the partial C3-N double bond) is formed exclusively. Products derived from addition of H2NR to the C1C2 bond of 1a are not observed. The amino group in 1d-w is rapidly deprotonated by excess of amine to form iminium alkynyl chromates [1d-w]−, thus protecting 1d-w from addition of free amine to either C3 or across the C1C2 bond. The iminium alkynyl chromates are readily reprotonated by acids or by chromatography on wet SiO2 to reform 1d-w. 相似文献
3.
Normen Szesni 《Inorganica chimica acta》2004,357(6):1789-1798
Photolysis of the allenylidene pentacarbonyl chromium complexes [(CO)5CrCCC(R1)R2] (R1=NMe2, NPh2; R2=NMe2, OMe, Ph) in THF in the presence of equimolar amounts of XR3 (XR3=various phosphanes, P(OMe)3, AsPh3, SbPh3) affords cis-allenylidene tetracarbonyl XR3 complexes, cis-[(CO)4(XR3)CrCCC(R1)R2]. When in the photolysis of [(CO)5CrCCC(NMe2)Ph], the phosphanes PR3 (R=C6H4F-p, C6H4Cl-p, OMe) are used in excess (three equivalents) two carbonyl ligands are displaced and the mer-tricarbonyl complexes mer-[(CO)3(PR3)2CrCCC(NMe2)Ph] are formed both PR3 ligands being mutually trans. The structure of the new complexes is established by IR, NMR, and UV-Vis spectroscopy, that of cis-[(CO)4(PPh3)CrCCC(NMe2)Ph] additionally by an X-ray structural analysis. As indicated by the spectroscopic data of the compounds, these complexes are best described as hybrids of allenylidene and zwitterionic alkynyl complexes with delocalization of the electron pair at nitrogen bonded to the Cγ atom of the allenylidene ligand towards the metal center. The relative contribution of the allenylidene and zwitterionic alkynyl resonance forms is influenced by XR3. Increasing the donor properties of XR3 favors the allenylidene resonance form. 相似文献
4.
Florian Kessler 《Inorganica chimica acta》2011,374(1):278-6282
The platinum(0) complex [Pt(PPh3)4] reacts with brominated propargylic amides and esters in benzene by oxidative addition to give trans-[Br(PPh3)2Pt-CC-C(O)R] complexes whereas no reaction occurs when halogenated solvents (CH2Cl2, CHCl3) are used. The cis-ligands PPh3 can be replaced by P(iPr)3 and the bromide by trifluoroacetate. O-Alkylation of those trans-[X(PR′3)2Pt-CC-C(O)R] complexes (X = Br, CF3COO; R′ = Ph, iPr) derived from propargylic amides with MeOTf or [Me3O]BF4 in CH2Cl2 gives the first cationic monoallenylidene complexes of platinum, trans-[X(PR′3)2PtCCC(OMe)NR2]+Y− (Y = OTf, BF4). In contrast, trans-[Br(PPh3)2Pt-CC-C(O)OMenthyl] derived from a propargylic ester does not react with MeOTf in CH2Cl2. However, in acetonitrile instead of O-methylation the substitution of acetonitrile for the bromide ligand to yield the cationic acetonitrile alkynyl platinum complex trans-[MeCN(PPh3)2Pt-CC-C(O)OMenthyl]+OTf− is observed. The related palladium complexes trans-[X(PR′3)2Pd-CC-C(O)OR] (X = Br, CF3COO; R′ = Ph, iPr, R = menthyl, Et) react with MeOTf or [Et3O]BF4 analogously affording trans-[MeCN(PR′3)2Pd-CC-C(O)OR]+Y− (Y = OTf, BF4). 相似文献
5.
The 16-electron complex (CO)4W=C(NMe2)SiPh2Me (1) was photochemically prepared from (CO)5W=C- (NMe2)SiPh2Me. Reactions with selected nucleophiles, having different ligand properties, were performed to test the strength of the intramolecular agostic interaction of one of the phenyl groups, by which 1 is stabilized. The stable complexes cis-(CO)4LW=C(NMe2)SiPh2Me were formed with L=P(OMe)3, P(OEt)3 or 2,6-Me2C6H3NC. The substituted complexes had no tendency for ligand elimination. Addition of acetonitrile or pyridine to an ether solution of 1 resulted in the formation of cis-(CO)4(MeCN)W=C(NMe2)SiPh2Me or cis-(CO)4(C5H5N)- W=C(NMe2)SiPh2Me, respectively. These reactions were reversed on evaporation of the solutions. No reaction was observed with triethylamine. 相似文献
6.
Guido D. Frey Karl Öfele Herbert G. Krist Eberhardt Herdtweck Wolfgang A. Herrmann 《Inorganica chimica acta》2006,359(9):2622-2634
In order to study the relative stability of cis- and trans-isomers of bis(NHC)tetracarbonyl complexes of group 6 metals, we synthesized the corresponding complexes with triazolin- and tetrazolinylidene ligands. By reaction of the free carbene (L = 1,3,4-triphenyl-4,5-dihydro-1H-1,2,4-triazolin-5-ylidene) - first synthesized by Enders - with the hexacarbonyls of Cr, Mo and W the corresponding M(L)(CO)5 complexes are generated. Depending on an excess of carbene also the cis-(L)2Mo(CO)4 complex was obtained. The latter can be photolytically converted to the trans-(L)2Mo(CO)4 complex. The corresponding complexes with the 1,4-dimethyltetrazolin-5-ylidene ligand (L′), Cr(L′)(CO)5, cis-(L′)2Cr(CO)4 and trans-(L′)2Cr(CO)4 can be obtained by reaction of hexacarbonyl-μ-trihydroxy-dichromate with dimethyltetrazolium salt. In the cis-(L′)2Cr(CO)4 complex, one carbonyl ligand can be replaced by donor ligands such as pyridine or phenylisocyanide to form sym-mer-tricarbonyl complexes. All new complexes are fully characterized by spectroscopy and most by single-crystal X-ray analysis. 相似文献
7.
The reactions of [(H5C6)3P]2ReH6− with (CH3CN)3Cr(CO)3, (diglyme)Mo(CO)3 or (C3H7CN)3W(CO)3 led to the formation of [(H5C6)3P]2ReH6M(CO)3− (M = Cr, Mo, W) complexes. These have been characterized by IR and NMR spectroscopies, as well as elemental analyses. A single crystal X-ray diffraction study has also been carried out for the M = Cr complex as a K(18-crown-6)+ salt. The complex crystallizes as a THF monosolvate in the monoclinic space group P21/n with a = 22.323(6), B = 9.523(2), C = 27.502(5) Å, β = 104.98(2)0 and V = 5648 Å3 for Z = 4. The Re---Cr separation is 2.5745(12) Å, and the two phosphine ligands are oriented unsymmetrically. Although the hydride ligands were not found, the presence of three bridging hydrides and a dodecahedral coordination geometry about rhenium could be inferred. Low temperature 1H and 31P NMR spectroscopic studies did not reveal the low symmetry of the solid state structure. 相似文献
8.
William D. Wulff Benjamin A. Anderson Amanda J. Toole Yao-Chang Xu 《Inorganica chimica acta》1994,220(1-2):215-231
The aldol reactions of tetracarbonyl(phosphine)methyl(methoxy)methylene chromium complexes and pentacarbonylmethyl (dialkylamino)methylene chromium complexes with aldehydes and ketones were examined. The reactions of the phosphine complexes give only aldol condensation products, but the desired aldol addition products can be isolated from the reactions of amino carbene complexes. This was attributed to the greater reactivity of the enolates of amino carbene complexes which is supported by a determination of the thermodynamic acidity of the dimethylamino complex 13 (pKa=20.4). The aldol reactions of amino complexes with -chiral aldehydes occur with very high facial selectivities rivaling the best methods that have been developed for facial selectivity in the aldol reaction. The aldol reactions of amino complexes can be considered as direct synthons for amides since amide functions can be obtained in the oxidative cleavage of the aldol adducts of these complexes. As illustrative of the versatility of carbene complexes, it is also demonstrated in a photo-induced carbon-homologative demetallation, that in combination with the aldol addition reaction the unique reactions of carbene complexes provide powerful and novel overall transformations. 相似文献
9.
The heterotrimetallic complex, [{LCuMn(H2O)}{Cr(phen)(C2O4)2}](ClO4) · H2O (1), has been obtained by assembling heterobinuclear cations, [LCuMn]2+, with [Cr(phen)(C2O4)2]− ions (H2L is the compartmental Schiff-base resulting from the stepwise condensation of 2,6-diformyl-p-cresol with ethylenediamine and diethylenetriamine). The copper(II) and manganese(II) ions are hosted into the compartments of the macrocyclic ligand. [Cr(phen)(C2O4)2]− acts as a ligand, being coordinated through one oxalato oxygen atom to the apical position of the square pyramidal copper(II) ion. The cryomagnetic investigation of 1 reveals an antiferromagnetic interaction between CuII and MnII within the compartmental ligand (J = −39 cm−1). The interaction between CuII and CrIII across the oxalato bridge is negligible. The crystal structure of [LCuPb](ClO4)2 · H2O, a useful precursor in obtaining 3d-3d′ complexes, is also reported. 相似文献
10.
Ba L. Tran 《Inorganica chimica acta》2007,360(6):1961-1969
Twelve new dioxo W(VI) complexes of a family of heteroscorpionate ligands of the type [(L)WO2Y], where L = N2X ligand and Y = Cl or OR, have been synthesized and characterized. With the more sterically bulky ligands we show that these complexes exist as isolable cis and trans isomers and compare the rate of such isomerization with their corresponding dioxo Mo(VI) analogs. 相似文献
11.
The kinetics of the anation reactions of [M(RNH2)5H2O]3+ (M = Rh, R = H, Me, Et, Pr; M = Cr, R = H, Me, Pr) with several ligands (H3PO4/H2PO4−, H3PO3/H2PO3−, CF3COO−, Br−, Cl−, SCN−) have been studied at different temperatures and acidities at I = 1.0 M (LiClO4. Results obtained for the anation rate constants and thermal activation parameters are compared with the previously published data for R = H, in order to establish the effects of the amine substituents in the reaction mechanism proposed for the substitution reactions of these complexes. The results obtained are interpreted on the basis of a mechanism where the bond formation process is more important in the substitution on M = Cr complexes than in that of the M = Rh complexes, as already pointed out for the published ΔΛ≠ values for the water exchange on these systems. A simple Langford-Gray classification becomes inadequate to describe these situations where the increase of the steric demand of the amine substituents shifta the Ia-Id classification to the Id side, although no dramatic changes in the reaction mechanism are found. It is concluded that a More O'Ferall ‘continuous’ type of approach to the mechanism classification of the substitution reactions is much more useful in this case. 相似文献
12.
Olivier Schott Abdeslem Bentama Salah-Eddine Stiriba Jorge Pasán Marius Andruh Miguel Julve 《Inorganica chimica acta》2011,376(1):358-366
The preparation, crystal structure and variable temperature-magnetic investigation of three 2-(2′-pyridyl)imidazole-containing chromium(III) complexes of formula PPh4[Cr(pyim)(C2O4)2]·H2O (1), AsPh4[Cr(pyim)(C2O4)2]·H2O (2) and [Cr2(pyim)2(C2O4)2(OH2)2]·2pyim · 6H2O (3) [pyim = 2-(2′-pyridyl)imidazole, , and ] are reported herein. The isomorphous compounds are made up of discrete [Cr(pyim)(C2O4)2]− anions, cations [X = P (1) and As (2)] and uncoordinated water molecules. The chromium environment in 1 and 2 is distorted octahedral with Cr-N and Cr-O bond distances varying in the ranges 2.040(3)-2.101(3) and 1.941(3)-1.959(3) Å, respectively. The angle subtended by the chromium(III) ion by the two didentate oxalate ligands cover the range 82.49(12)-82.95(12)°, values which are somewhat greater than those concerning the chelating pyim molecule [77.94(13) (1) and 78.50(13)° (2)]. Complex 3 contains discrete centrosymmetric [Cr2(pyim)2(C2O4)2(OH)2] neutral units where the two chromium(III) ions are joined by a di-μ-hydroxo bridge, the oxalate and pyim groups acting as peripheral didentate ligands. Uncoordinated water and pyim molecules are also present in 3 and they contribute to the stabilization of its structure by extensive hydrogen bonding and π-π type interactions. The values of the intramolecular chromium-chromium separation and angle at the hydroxo bridge in 3 are 2.9908(12) Å and 99.60(16)°, respectively. Magnetic susceptibility measurements of 1-3 in the temperature range 1.9-300 K show the occurrence of weak inter- (1 and 2) and intramolecular (3) antiferromagnetic couplings. The magnetic properties of 3 have been interpreted in terms of a temperature-dependent exchange integral, small changes of the angle at the hydroxo bridge upon cooling being most likely responsible for this peculiar magnetic behavior. 相似文献
13.
Marilé Landman James Ramontja Daniela I. Bezuidenhout David C. Liles 《Inorganica chimica acta》2010,363(4):705-9403
The syntheses and structures of homo- and heteronuclear biscarbene complexes with bithiophene spacers were investigated. The complexes were synthesized by lithiation of bithiophene followed by metallation using combinations of the metal precursors MnMeCp(CO)3, W(CO)6, Mo(CO)6 and Cr(CO)6, after which the reaction was quenched with triethyloxonium tetrafluoroborate. This classical Fischer method yielded monocarbene complexes, [MLnC(OEt)C4H2S-C4H3S], ([MLn] = Cr(CO)51a, W(CO)52a or MnMeCp(CO)23a), homonuclear biscarbene complexes, [MLnC(OEt)C4H2S-C4H2SC(OEt)MLn], ([MLn] = Cr(CO)51b, W(CO)52b or MnMeCp(CO)23b) and heteronuclear biscarbene complexes, [MLnC(OEt)C4H2S-C4H2SC(OEt)M′Ln] (1d: [MLn] = Cr(CO)5 and [M′Ln] = W(CO)5; 1e: [MLn] = MnMeCp(CO)2 and [M′Ln] = Cr(CO)5; 1f: [MLn] = Cr(CO)5 and [M′] = Mo(CO)5); 2d: [MLn] = MnMeCp(CO)2 and [M′Ln] = W(CO)5; 3c: [MLn] = MnMeCp(CO)2 and [M′Ln] = Mo(CO)5). Electron density calculations with the gaussian03 software package of 1e revealed a polar rod with the negative pole towards the chromium carbene side, whereas the biscarbenes 1d and 1b showed very little polarity. By-products resulting from activation of the carbene moieties in homonuclear biscarbene complexes included (i) ester-type complexes of the form [MLnC(OEt)C4H2S-C4H2SC(O)OEt], ([MLn] = Cr(CO)51c or W(CO)52c), formed in situ in the reaction of 1b and 2b, (ii) the organic bis-ester compound [EtOC(O)C4H2S-C4H2SC(O)OEt] 4, where both metal moieties had been substituted by oxygen and (iii) the carbon-carbon coupled dimeric bithienyl compound [C4H3S-C4H2SC(O)C(O)C4H2S-C4H3S] 5. By-products obtained from heteronuclear biscarbene reactions contain the former diketo compound (or a derivative) as spacer between two metal carbonyl fragments and have the general formula [MLnC(OEt)C4H2S-C4H2SCR-CR′C4H2S-C4H2SC(OEt)MLn] (5a: [M] = Cr(CO)5, R = OH, R′ = OEt; 5b: [M] = W(CO)5, R = R′ = O; 5c: [M] = Mo(CO)5, R = R′ = O). Reaction of 1d, 1e and 1f with hex-3-yne resulted in the formation of benzannulated products 6a, 6b and 6c. All novel complexes were fully characterized using various spectroscopic techniques. The crystal structures of 1b, 2a and 5 are reported. 相似文献
14.
Mauricio Isaacs 《Inorganica chimica acta》2006,359(12):3847-3854
A series of new heteroleptic, tris(polypyridyl)chromium(III) complexes, [Cr(phen)2L]3+ (L = substituted phenanthrolines or bipyridines), has been prepared and characterized, and their photophyical properties in a number of solvents have been investigated. X-ray crystallography measurements confirmed that the cationic (3+) units contain only one ligand L plus two phenanthroline ligands. Electrochemical and photophysical data showed that both ground state potentials and lifetime decays are sensitive to ligand structure and the nature of the solvent with the exception of compounds containing L = 5-amino-1,10-phenanthroline (aphen) and 2,2′-bipyrimidine (bpm). Addition of electron-donating groups in the ligand structure shifts redox potentials to more negative values than those observed for the parent compound, [Cr(phen)3]3+. Emission decays show a complex dependence with the solvent. The longest lifetime was observed for [Cr(phen)2(dip)]3+ (dip = 4,7-diphenylphenanthroline) in air-free aqueous solutions, τ = 273 μs. Solvent effects are explained in terms of the affinity of hydrophobic complexes for non-polar solvent molecules and the solvent microstructure surrounding chromium units. 相似文献
15.
A preparative procedure of potentially wide applicability is described for the synthesis of previously unreported tris(heteroleptic) [Cr(diimine)3]3+ complexes. The synthetic scheme involves the sequential addition of three different diimine ligands, and employs CrCl3 · 6H2O as the initial Cr(III) reagent. The synthesis and characterization of the complexes [Cr(TMP)(phen)(diimine′)]3+ are reported (where TMP = 3,4,7,8-tetramethyl-1,10-phenanthroline, phen = 1,10-phenanthroline; and diimine′ is either bpy = 2,2′-bipyridine, Me2bpy = 4,4′-dimethyl-2,2′-bipyridine, 5-Clphen = 5-chloro-1,10-phenanthroline, or DPPZ = dipyridophenazine). Chiral capillary electrophoresis and electrospray mass spectrometry were essential aids in determining the presence or absence of diimine ligand scrambling. Utilizing emission and electrochemical data obtained on these compounds, the oxidizing power of the lowest lying excited state (2Eg(Oh)) was calculated, and was found to vary in a systematic fashion with diimine ligand type. 相似文献
16.
Jean-Fran ois Capon Nathalie Le Berre-Cosquer Fran oise Chuburu Ren Kergoat Jean-Yves Saillard 《Inorganica chimica acta》1996,250(1-2):119-127
The reactivity, towards nucleophiles and electrophiles, of dimolybdenum allenylidene complexes of the type [Cp2Mo2(CO)4(μ,η2(4e)-C=C=CR1R2)] (Cp=η5-C5H5) has been investigated. The nucleophilic attacks occur at the Cγ carbon atom, while electrophiles affec the C atom. Variable temperature solution 1H NMR studies show a dynamic behavior of these complexes consisting of an equilibrium between two enantiomers with a symmetrical [Cp2Mo2(CO)4(μ-σ,σ(2e)-C=C=CR1R2)] transition state. Extended Hückel MO calculations have been carried out on the model [Cp2Mo2(CO)4(μ,η2-C=C=CH2]. The calculated charges of the allenylidene carbon atoms suggest that the electrophilic attacks are under charge control, while the nucleophilic attacks are rather under orbital control. 相似文献
17.
Frank T. Edelmann 《Inorganica chimica acta》2004,357(15):4592-4595
The preparation and characterization of a series of deuterium-labelled (fulvene)M(CO)3 (M = Cr, Mo) complexes is reported. (η5-6-Dimethylaminofulvene-d2)Cr(CO)3 and (η5-6-dimethylaminofulvene-d2)Mo(CO)3 were obtained in high yields by reacting the deuterated fulvene ligands with (MeCN)3M(CO)3 (M = Cr, Mo). In addition, syntheses of 6,6-diphenylfulvene-d10 and 6,6-diphenyl-1,2-benzofulvene-d10 as well as the corresponding tricarbonylchromium complexes are described. 相似文献
18.
Bis(pyridine) complexes of molybdenum and tungsten, [M(η3-allyl)Cl(CO)2(NC5H5)2] (M=Mo; 3-Mo, M=W; 3-W), reacted with an equimolar amount of lithiated amidinate, Li[(PhN)2CR] (R=H; 4a-Li, R = CH3; 4b-Li), to yield corresponding amidinato(pyridine) complexes, [M(η3-allyl){(PhN)2CR}(CO)2(NC5H5)] (M=Mo, R=H; 5a-Mo, M=Mo, R=CH3; 5b-Mo, M=W, R=H; 5a-W), as a yellow solid. The dissociation of pyridine ligand from the central metal in complexes 5a was observed in a polar solvent such as acetonitrile. In these cases, although the formation of amidinato(acetonitrile) complexes, [M(η3-allyl){(PhN)2CH}(CO)2(NCMe)] (M=Mo; 6a-Mo, M=W; 6a-W), was suggested spectroscopically, isolation of complexes 6a was not successful but the re-formation of pyridine complexes 5a was observed. In the reactions of complexes 5a with PEt3 and with P(OMe)3, the substitution reactions easily took place to give [M(η3-allyl){(PhN)2CH}(CO)2(PEt3)] (M=Mo; 7a-Mo, M=W; 7a-W) and [M(η3-allyl){(PhN)2CH}(CO)2{P(OMe)3}] (M=Mo; 8a-Mo, M=W; 8a-W), respectively. These complexes were characterized spectroscopically as well as, in some cases, by X-ray analyses. 相似文献
19.
Donald J. Darensbourg Kevin K. Klausmeyer Jennifer D. Draper Jennifer A. Chojnacki Joseph H. Reibenspies 《Inorganica chimica acta》1998,270(1-2):405-413
The complex [Et4N][W(CO)5OMe] (1) has been prepared from the reaction of the photochemically generated W(CO)5THF adduct and [Et4N][OH] in methanol. Complex 1 was shown to undergo rapid CO dissociation in THF to quantitatively provide the dimeric dianion, [W(CO)4OMe]22−. The resulting THF insoluble salt [Et4N]2[W(CO)4OMe]2 (2) has been structurally characterized by X-ray crystallography, with the doubly bridging methoxide ligands being in an anti configuration. Complex 2 was found to subsequently react with excess methoxide ligand in a THF slurry to afford the face-sharing octahedron complex [Et4N]3[W2(CO)6(OMe)3] (3) which contains three doubly bridging methoxide groups. In the absence of excess methoxide ligand complex 2 cleanly yields the tetrameric complex [Et4N]4[W(CO)3OMe]4 (4) which has been structurally characterized as a cubane-like arrangement with triply bridging μ3-methoxide groups and W(CO)3 units. Although complex 3 was not characterized in the solid state, the closely related glycolate derivative [Et4N]3[W2(CO)6(OCH2CH2OH)3] (5) was synthesized and its structure determined by X-ray crystallography. The trianions of complex 5 are linked in the crystal lattice by strong intermolecular hydrogen bonds. Crystal data for 2: space group P21/n, a = 7.696(2), b = 22.019(4), c = 9.714(2) Å, β = 92.22(3)°, Z = 4, R = 6.43%. Crystal data for 4: space group Fddd, a = 12.433(9), b = 24.01(2), c = 39.29(3) Å, Z = 8, R = 8.13%. Crystal data for 5: space group P212121, a = 11.43(2), b = 12.91(1), c = 29.85(6) Å, Z = 8, R = 8.29%. Finally, the rate of CO ligand dissociation in the closely related aryloxide derivatives [Et4N][W(CO)5OR] (R = C6H5 and 3,5-F2C6H3) were measured to be 2.15 × 10−2 and 1.31 × 10−3 s−1, respectively, in THF solution at 5°C. Hence, the value of the rate constant of 2.15 × 10−2 s−1 establishes a lower limit for the first-order rate constant for CO loss in the W(CO)5OMe− anion, since the methoxide ligand is a better π-donating group than phenoxide. 相似文献
20.
WH3(OCH2C6H5) (PMe3)4 (1) is formed upon reaction of WH2(PMe3)5 with benzyl alcohol for 12 days at ambient temperatures. Thermolysis of 1 at 80°C in toluene solution gives the carbonyl complex, WH2(CO)(PMe3)4 (2) and benzene. The conversion is slower in the presence of H2. Reaction of 1 with D2 leads to H/D exchange in the hydride ligands and in the benzylic and ortho-phenyl positions of the benzyloxide. A mechanism for the thermolysis of 1, based on an H2 elimination, sequential C-H activations, and CO deinsertion from an acyl ligand, is proposed. Thermolysis of 1 is much faster in the presence of free benzyl alcohol and 2 is not formed. The products under these conditions are toluene, bibenzyl, WH4(PMe3)4, PMe3 and unidentified material, consistent with the intermediacy of benzyl radicals. 相似文献