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1.
13C and 31P{1H} NMR data at low temperature prompted us to characterize cis-[Rh(CO)2(PR3)Cl] (3) (3a, PR3 = PPh3; 3b, PR3 = PMe2Ph), as surprisingly stable products of the reaction between [{Rh(CO)2(μ-Cl)}2] (1) and tertiary phosphines in toluene (P : Rh = 1). Every attempt to isolate solid 3a led to the cis- and trans- halide-bridged dimers [{Rh(CO)2(μ-Cl)}2] (5a) and 6a which are formed from 3a by slow decarbonylation, a process which is greatly accelerated by the evaporation of the solvent under vacuum.

The analogous reaction of 1 with dimethylphenylphosphine follows a similar pathway; in this case, however, low temperature NMR spectra allowed us to characterize the pentacoordinated dinuclear species [{Rh(CO)2(μ-Cl)}2] (2b) as the unstable intermediate of the bridge-splitting process.

The reaction of 3 with a second equivalent of phosphine (P : Rh = 2) leads, at room temperature, to the well known product trans-[Rh(CO)(PR3)2Cl] (8) accompanied by evolution of CO; however our data show that when the reaction is performed at 200 K, decarbonylation is prevented and spectroscopic evidence of trigonal bipyramidal pentacoordinate [Rh(CO)2(PR3)2Cl] (7), stable only at low temperature, can be obtained.  相似文献   


2.
The complexes (Hal)Nb(CO)3(PR3)3 (PR3 = PEt3, Hal = I; PR3 = PMe2Ph, Hal = Cl, Br, I) and (Hal)Nb(CO)4/2(dppe)1/2 (Hal = Br, I) have been prepared by oxidative halogenation of carbonylniobate with pyridinium halides (Hal = Cl, Br) or iodine (Hal = I). In the tricarbonyls, one CO and one PR3 are labile and can be displaced by a four-electron donating alkyne to give all-trans-[(Hal)Nb(CO)2(RCCR′)(PR3)2] (PR3 = PMe2Ph; Hal = Cl, Br, I: R, R′ = H, Et, Ph; R = H, R′ = Ph. PR3 = PEt3, Hal = I: R, R′ = Pr; R = H, R′ = Bu, Ph; R = Me, R′ = Et). In the case of acetylene, INb(CO)(HCCH)2(PEt3)2 is also formed. PR3 can be displaced by P(OMe) 3. In the tetracarbonyls, two CO ligands are replaced by two isonitriles to form INb(CO)2(CNR)2dppe (R = tBu, Cy), or by one alkyne to form (Hal)Nb(CO)2(PhCCPh)dppe (Hal = Br, I). In these complexes, the remaining CO ligands occupy cis positions. The structure of BrNb(CO)2(dppe)2·THF, INb(CO)2(dppe)2·hexane and INb(CO)2(PEt3)2(MeCCEt) have been determined by a single crystal X-ray diffraction study. The alkyne complexes are best regarded as octahedral with the centre of the alkyne ligand occupying the positions trans to the halide and the CC axis aligned with the OC---Nb---CO axis. The complexes (Hal)Nb(CO)2(dppe)2 adopt a trigonal prismatic structure with the halide capping the tetragonal face spanned by the four phosphorus functions. The crystal structure of a by-product, Br2Nb(CO)(H2CPhPCH2CH2PPh2)2·1/2THF has also been determined. The geometry is pentagonal bipyramidal, with one of the bromine atoms and the CO on the axis. Some 93 Nb NMR data for the NbI complexes are presented, and preliminary observations on the reactions between the π-alkyne complexes and H2 or H are reported.  相似文献   

3.
The electrochemical behaviour of a series of Mo2Cl4(PR3)4 complexes (PR3 = PMe3, PEt3, PPrn3,PBun3, PH2Ph, PMe2Ph, PEt2Ph, PHPh2, PMePh2, PEtPh2, P(OMe)3, P(OMe)Ph2) has been examined by cyclic voltammetry in dichloromethane solution. The phosphines were chosen to provide a wide range of Lewis basicity/π acidity as reflected by Tolman's co IR and Bodner's Δδco 13C NMR spectral parameters for Ni(CO)3(PR3). The Mo2 compounds undergo either quasi-reversible or irreversible one-electron oxidations except for P(OMe)3 and P(OMe)Ph2 for which no clectroactivity was observed before the solvent limit. The anodic peak potentials, Ep,a, span a range of nearly 700 mV. The half-wave potentials, E1/2,for the quasi-reversible couples and Ep,a for all were plotted against the IR and NMR values and against the δ → δ* transition energies for the Mo2 species in dichloromethane and in the solid state. For the organometallic spectral parameters excellent linear correlations were obtained while with the electronic spectral data fair correlations resulted. These results indicate that the Mo2Cl4(PR3)4 complexes become more difficult to oxidize as the electron-withdrawing nature of the PR3 substituents increases and the δ → δ* band energy decreases.  相似文献   

4.
The complexes [Ru(S,S)2(PPh3)2] [S,S = EtCOCS2, (CH2)4NCS2] react with a variety of tertiary phosphines with the substitution of triphenylphosphine and the formation of [Ru(S,S)2(PR3)2]. The reaction occurs with the formation ofthe cis isomer, except for the complex with PMe2Ph that gives rise to the trans isomer as the crystal structure shows. The effect of the different phosphines on the ruthenium complex is analysed in terms of the spectroscopic and electrochemical properties of the isolated compounds. The cyclic voltammetric studies of the cis complexes show that isomerization to the trans isomer occurs on oxidation. This isomerization is not observed in the trans-[Ru(S,S)2(PMe2Ph)2] complexes that give rise to stable trans-ruthenium(II)/ruthenium(III) couples. In a similar way the diphosphine complexes afford a quasi-reversible cis-ruthenium(II)/ruthenium(III) process.  相似文献   

5.
Reaction of C5H4(SiMe3)2 with Mo(CO)6 yielded [(η5-C5H3(SiMe3)2)Mo(CO)3]2, which on addition of iodine gave [(η5-C5H3(SiMe3)2Mo(CO)3I]. Carbonyl displacement by a range of ligands: [L = P(OMe)3, P(OPri)3,P(O-o-tol)3, PMe3, PMe2Ph, PMePh2, PPh3, P(m-tol)3] gave the new complexes [(η5-C5H3(SiMe3)2 MO(CO)2(L)I]. For all the trans isomer was the dominant, if not exclusive, isomer formed in the reaction. An NOE spectral analysis of [(η5-C5H3(SiMe3)2)Mo(CO)2(L)I] L = PMe2Ph, P(OMe)3] revealed that the L group resided on the sterically uncongested side of the cyclopentadienyl ligand and that the ligand did not access the congested side of the molecule. Quantification of this phenomenon [L = P(OMe)3] was achieved by means of the vertex angle of overlap methodology. This methodology revealed a steric preference with the trans isomer (less congestion of CO than I with an SiMe3 group) being the more stable isomer for L = P(OMe)3.  相似文献   

6.
Reaction of R---N=C=N---R (R=p-Me-C6H4) and R---P==C=P---R (R=2,4,6-tBu3C6H2) with the di-iron aminocarbene complex [Fe2(CO)7{1μ-C(Ph)C(NEt2)}] (1c) gave corresponding complexes [Fe2(CO)6{C(Ph)C(NEt2)C(NC6H4Me)N (C6H4Me)}] (2) and [Fe2(CO)6{C(Ph)C(NEt2)C(PC6H2tBu3)P(C6H2tBu3)}] (4), resulting from a coupling reaction with carbon-carbon bond formation. [Fe2(CO)5(CNC6H4Me){C(Ph)C(NEt2)N(C6H4Me)}], complex 3, obtained in the reaction with R---N=C=N---R, resulted from C=N bond rupture insertion of a nitrene fragment into the Fe=C bond. Complexes 2–4 were characterized by X-ray diffraction. The different geornetries of complexes 2 and 4 are discussed. The formation of these complexes may be explained by cycloaddition on the Fe =C metal-carbene bond.  相似文献   

7.
The equilibrium constants of the reaction of cis, trans-[Ru(CO)2(PMe3)2(CH3)I] (Mc) with carbon monoxide to give cis, trans[Ru(CO)2(PMe3)2 (COMe)i] (Ac) and trans, trans[Ru(CO)2(PMe3)2(COMe)I] (At) were measured at various temperatures in toluene. The thermodynamic parameters are compared with those obtained for the isoelectronic complexes of iron, and the trend is discussed. The kinetics of the carbonylation reaction of Mc, as well as those of the inverse decarbonylation reaction of At were measured. The kinetics of the carbonylation of the new complex trans, trans-[Ru(CO)2(PMe3)2(CH3)I] (Mt) were also investigated. All the results afford further support to the previously proposed CO insertion mechanism occurring via methyl migration. The comparison of these kinetic results with those of isoelectronic complexes of iron indicates that ruthenium is more reactive than iron, which is reflected by its greater aptitude to act as catalyst in many processes.  相似文献   

8.
Two new types of heteropolymetallic complexes FeRu2(μ-OH)2(CO)8(PR3)2 and FeRu2(μ-H)(μ-OH)(CO)8(PR3)2 have been obtained in acetone and isopropanol, respectively, from the reaction of FeRu2(μ-Cl)2 complexes with bases. They contained a Ru---Fe---Ru bent-chain with the bridging groups holding the ruthenium atoms.  相似文献   

9.
The complexes [(η6-arene)Ru=C(OMe)CH2R′)Cl(PR3)]PF6 (R′ = Ph; ARENE = Me4C6H2, iPr3C6H3, Et3C6H3; PR3 = PMe3, PPh3, P(OMe)3) have been made from RuCl2(PR3)(arene) precursors by activation at room temperature of phenylacetylene in methanol containing NaPF6. The complex with R′ = nBu, ARENE = Me4C6H2, and PR3 = PMe3 is similarly formed from hex-1-yne but much more slowly, and a complex of the type [(p-cymene)Ru=C(OMe)CH2R′)Cl(PR3)]+PF6 could be obtained only when the phosphine was the bulky PPh3 (10b). It has been shown that the steric hindrance by both arene and phosphine ligands contributes to the stabilization of the carbeneruthenium complexes.  相似文献   

10.
The homogeneous, Rh-catalysed hydrosilylation of but-2-yne with triethoxysilane has been studied. All rhodium complexes employed as catalyst precursors contain tBu2PCH2PtBu2 (“dtbpm”) as a chelating ligand. The crystal and molecular structure of the dimer [(dtbpm)RhCl]2 (10) has been determined by X-ray diffraction. Complex 10 is shown to be a sluggish catalyst in hydrosilylation reactions of hex-1-ene, whereas but-2-yne is hydrosilylated more rapidly. A much more efficient and highly selective catalyst is 10 with added PPh3, equivalent to the use of monomeric (dtbpm)RhCl(PPh3). (E)-2-Triethoxysilylbut-2-ene is formed exclusively and with high turnover numbers in this case. For both 10 and its PPh3 derivative, the 14-electron fragment [(dtbpm)RhCl], formed by dissociation processes, is the most likely active intermediate in a Harrod-Chalk-type catalytic cycle. The PPh3 dissociation equilibrium has been studied in detail for (dtbpm)RhCl(PPh3) and its thermodynamic parameters have been determined. With rhodium alkyl complexes as catalyst precursors, a different type of alkyne hydrosilylation catalysis, involving direct alkyne insertion into the Rh---Si bond of an intermediate rhodium silyl complex, (dtbpm)Rh[Si(OEt)3](PMe3) (14), has been found. Complex 14 was synthesized independently from (dtbpm)RhMe(PMe3) and characterized by X-ray diffraction. It is an equally active catalyst itself, yielding (E)-2-triethoxysilylbut-2-ene as the major product (90%) from but-2-yne and HSi(OEt)3 (turnover number 1000 per 30 min). The insertion step of the alkyne into the Rh---Si bond of 14 and the formation of two stereoisomeric rhodium vinyl complexes were established independently for MeO2CCCCO2Me as a more reactive alkyne substrate. A catalytic cycle is proposed for this unprecedented hydrosilylation reaction. The synthesis of the ν3-benzyl complex (dtbpm)Rh(η3-CH2C6H5) (23) is described. This compound allows an alternative, more efficient access to the new silyl complex (dtbpm)Rh[Si(OEt)3](PMe3).  相似文献   

11.
Treatment of ruthenium complexes [CpRu(AN)3][PF6] (1a) (AN=acetonitrile) with iron complexes CpFe(CO)2X (2a–2c) (X=Cl, Br, I) and CpFe(CO)L′X (6a–6g) (L′=PMe3, PMe2Ph, PMePh2, PPh3, P(OPh)3; X=Cl, Br, I) in refluxing CH2Cl2 for 3 h results in a triple ligand transfer reaction from iron to ruthenium to give stable ruthenium complexes CpRu(CO)2X (3a–3c) (X=Cl, Br, I) and CpRu(CO)L′X (7a–7g) (L′=PMe3, PMe2Ph, PMePh2, PPh3, P(OPh)3; X=Br, I), respectively. Similar reaction of [CpRu(L)(AN)2][PF6] (1b: L=CO, 1c: P(OMe)3) causes double ligand transfer to yield complexes 3a–3c and 7a–7h. Halide on iron, CO on iron or ruthenium, and two acetonitrile ligands on ruthenium are essential for the present ligand transfer reaction. The dinuclear ruthenium complex 11a [CpRu(CO)(μ-I)]2 was isolated from the reaction of 1a with 6a at 0°C. Complex 11a slowly decomposes in CH2Cl2 at room temperature to give 3a, and transforms into 7a by the reaction with PMe3.  相似文献   

12.
Reaction of the bis(dihydrogen) ruthenium complex RuH2(H2)2(PCy3)2 (1) with an excess of 9-borabicyclononane yields Ru[(μ-H)2BC8H14]2(PCy3) (6) and the phosphine adduct PCy3·HBC8H14. The new complex is characterized by NMR spectroscopy and X-ray diffraction. New X-ray data on 9-BBN dimer, from a measurement at 180 K, are also reported. DFT calculations (B3LYP) on Ru[(μ-H)2BC8H14]2(PMe3) (7), the PMe3 analogue of 6, confirm the ruthenium (II) formulation with two dihydroborate ligands. The data obtained using PH3 or PMe3 as models for PCy3 in PR3·HBC8H14 are also discussed.  相似文献   

13.
Addition of H2 to CH2Cl2 solutions of [(diene)Rh(L)2][closo-CB11H12] (diene=norbornadiene, cyclooctadiene, L=PCy3, P(OMe)3, 1/2dppe) results in the formation of the exo-closo complexes [(PR3)2Rh(closo-CB11H12)]. These have been characterised in solution by 1H- and 11B-NMR spectroscopy, and for L=PCy3 by a single crystal X-ray diffraction study. This suggests that the metal fragment is bound with the cage through the 7,8- and not the 7,12-{BH} vertices. DFT calculations on a model system where L=PMe3 show that there is only a negligible energy difference between these two isomers (1 kcal mol−1), suggesting that both represent stable structures. The salient spectroscopic markers that indicate an interaction of [closo-CB11H12] with a metal fragment are discussed and compared across a range of metal complexes. Large upfield shifts in the 11B-NMR spectrum and a small downfield shift of the CH vertex in the 1H-NMR spectrum are shown to the most reliable indicators of borane interaction in solution.  相似文献   

14.
Reactions of CpMoIr3(μ-CO)3(CO)8 (1) with stoichiometric amounts of phosphines afford the substitution products CpMoIr3(μ-CO)3(CO)8−x (L)x (L = PPh3, x = 1 (2), 2 (3); L = PMe3, x = 1 (4), 2 (5), 3 (6)) in fair to good yields (23–54%); the yields of both 3 and 6 are increased on reacting 1 with excess phosphine. Products 2–5 are fluxional in solution, with the interconverting isomers resolvable at low temperatures. A structural study of one isomer of 2 reveals that the three edges of an MoIr2 face of the tetrahedral core are spanned by bridging carbonyls, and that the iridium-bound triphenyiphosphine ligates radially and the molybdenum-bound cyclopentadienyl coordinates axially with respect to this Molr2 face. Information from this crystal structure, 31P NMR data (both solution and solid-state), and results with analogous tungsten—triiridium and tetrairidium clusters have been employed to suggest coordination geometries for the isomeric derivatives.  相似文献   

15.
用SiMe2ClH与Ru3(CO)12反应,得到顺式-Ru(CO)4(SiMe2Cl)2(I)和[Ru(CO)4(SiMe2Cl)]2(Ⅱ)。它们的SiMe2Cl配位基呈现较强的反位效应,由此合成得到一系列含膦(氧磷)或含卤素的衍生物。进行了Ⅰ-Ⅵ的元素分析、IR、1HNMR和MS表征。  相似文献   

16.
Reductive dehalogenation of the (chloro)(phenylethynyl)phosphine (2,4,6-tBu3C6H2O)(PhCC)PCl, I, by Co2(CO)8, II, yields the neutral phosphenium ion complex [(R)(R′)]P=Co(CO)3, III, (R = 2,4,6-tBu3C6H2O; R′ = (η2-C≡CPh)Co2(CO)6), which contains a trigonally planar coordinated phosphorus atom. When NaCo(CO)4, V, is used instead of II a dinuclear complex, Co2(CO)62-P(R)(R′)]2, VI, (R = 2,4,6-tBu3C6H2O; R′ = C≡CPh) is formed in which the phosphido ligands P(R)(R′), bridge in a μ2 fashion two Co(CO)3 units. The mechanism of formation of VI, involving a formal dimerization of two [(2,4,6-tBu3C6H2O)(PhC≡C)]P=Co(CO)3 fragments, is discussed. However, (tBu)(PhC≡C)PCl, VII, reacts with II, to yield the cluster compound VIII, containing the two μ2-bridging units (tBu)[(η2-C≡CPh)Co2(CO)5]P and (tBu)(PhC≡C)P.

Compounds II and VI–VIII were identified from their analytical and spectroscopic (IR, 1H-, 13C- and 31P-NMR) data. The molecular structure of the cluster compound VIII was determined by an X-ray diffraction study.  相似文献   


17.
[Mo2(OAc)4] reacts with three or more equivalents of lithium chloride and PMe3 in thf to give [Mo2Cl3(μ-OAc)(PMe3)3]0.75thf (1). The IR spectrum of the complex shows Mo---O and Mo---Cl stretches at 350 and 300 cm−1 respectively and the 1H and 13C NMR spectra suggest several species are present in solution. [Mo2Cl3(μ-OAc)(PMe3)3] converts slowly in thf to [Mo2Cl4(PMe3)4] and [Mo2(OAc)4]. The structure of [Mo2Cl3(μ-OAc) (PMe3)3]0.5C6H5Me (2) has been determined by single-crystal X-ray diffraction methods. Crystals of the toluene solvate are tetragonal with a = 20.726(2), c = 11.776(2) Å, space GROUP = I4cm. The structure was solved by Patterson and Fourier methods and refined to R of 0.035 for the 539 observed data. The molecule contains two metal centres each of which shows 5-fold coordination. The two molybdenum atoms are linked by an acetate bridge and a short Mo---Mo bond of 2.121(3) Å. Remaining coordination sites are occupied on Mo(1) by two Cl and one PMe3 and on Mo(2) by one Cl and two PMe3 groups.  相似文献   

18.
The aryldiazenido ligands provide the fourth member of the isoelectronic series CO, NO+, RNC, RN2+ of ligands for transition metal complexes. The first aryldiazenido metal complex was reported in 1964 when p-CH3OC6H4N2Mo(CO)2C5H5 was prepared by the reaction of NaMo(CO)3C5H5 with p-CH3OC6H4N2+BF4. This review surveys the development of organometallic aryldiazenido chemistry since that time. Such organometallic aryldiazenido derivatives, including RN2M(CO)2C5H5, RN2M(CO)2(Pz3BH) (M = Cr, Mo, W), [(η6-Me6C6)Cr(CO)2N2Ar]+, [(MeC15H4)M′(CO)2N2Ar]+ M′ = Mn, Re), [trans-PhN2Fe(CO)2(PPh3)2]+, and PhN2M′(CO)2(PPh3)2(PPh3)2 can be obtained by reactions of arenediazonium salts with suitably chosen transition metal nucleophiles. Analogous methods cannot be used to prepare alkyldiazenido transition metal complexes because of the instability of alkyldiazonium salts. However, the alkyldiazenido derivatives RCH2N2M(CO)2C5H5 (R = H or Me3Si) can be obtained from HM(CO)3C5H5 and the corresponding diazoalkanes. Important aspects of the chemical reactivity of RN2M(CO)2Q derivatives (Q = C5H5, Pz3BH) include CO substitution reactions, coordination of the second nitrogen in the RN2 ligand to give heterobimetallic complexes such as C5H5Mo(CO)2(μ-NNC6H4Me)(CO)2C5H5, oxidative addition rections with X2 X = Cl, Br, I), SnX4, RSSR, and CINO, and reactions with further RN2+ to give bis(aryldiazenido) derivatives (RN2)2MQL+ (L = CO, X, etc.). Dearylation of an aryldiazenido ligand to a dinitrogen ligand can be effected by reaction of [(MeC5H4)M′(CO)2N2Ar]+ with certain nucleophiles to give (MeC5H4)M′(CO)2N2.  相似文献   

19.
The complex C5H5(PMe3)Co(μ-CS)2CoC5H5 (I) is formed by the reaction of C5H5Co(PMe3)CS and CH2I2. The X-ray structure analysis shows an unsymmetrical non-planar Co2C2-skeleton with different Co---C bond lengths. The Co---Co distance is 239.2 pm. Compound I thus represents a new example of binuclear (18 + 16)-electron complexes in which the more electron-rich metal atom forms a donor bond to the more electron-poor counterpart. The reaction of I with ligands such as P(NMe2)3 does not lead to bridge cleavage indicating the stability of the Co(CS)2Co-framework.  相似文献   

20.
The reaction of bis(pyrazol-1-yl)methane tetracarbonylmolybdenum(0) or tungsten(0) complexes with RSnCl3 (R=Ph, Cl) at room temperature yielded heterobimetallic complexes CH2(Pz)2M(CO)3(Cl)(SnCl2R) (Pz represents substituted pyrazole; M=Mo or W; R=Ph or Cl) in good yields, which have been characterized by elemental analysis, 1H NMR and IR spectroscopy. The reaction of bis(3,5-dimethyl-4-halopyrazol-1-yl)methane tetracarbonyl tungsten with PhSnCl3 did not take place even in refluxing CH2Cl2. The electronic and steric characteristics of substituents on the pyrazole ring remarkably influence the structures of the products. The structures of CH2(3,5-Me2-4-BrPz)2W(CO)3(Cl)(SnCl3) (8) and CH2(4-BrPz)2Mo(CO)3(μ-Cl)(SnCl2Ph) (17) (Pz: pyrazole) determined by X-ray crystallography show that no chlorine-bridged W---Sn bond is observed in complex 8, while one chlorine-bridged Mo---Sn bond exists in complex 17. The Sn---M bond length is 2.7438(5) Å in complex 8 (W---Sn) and 2.7559(4) Å in complex 17 (Mo---Sn).  相似文献   

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