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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 chemistry of the di-μ-methylene-bis(pentamethylcyclopentadienyl-rhodium) complexes is reviewed. The complex [{(η5-C5Me5)RhCl2}2] (1a) reacted with MeLi to give, after oxidative work-up, blood-red cis-[{(η5-C5Me5)Rh(μ-CH2)}2(Me)2], 2. This has the two rhodiums in the +4 oxidation state (d5), and linked by a metal-metal bond (2.620 Å). Trans-2 was formed on isomerisation of cis-2 in the presence of Lewis acids, or by direct reaction of 1a with Al2Me6, followed by dehydrogenation with acetone. The Rh-methyls in [{(η5-C5Me5)Rh(μ-CH2)}2(Me)2] were readily replaced under acidic conditions (HX) to give [{(η5-C5Me5)Rh(μ-CH2)}2(X)2] (X = Cl, Br or I); these latter complexes reacted with a variety of RMgX to give [{(η5-C5Me5)Rh(μ-CH2)}2(R)2] (R = alkyl, Ph, vinyl, etc.). Trans-2 also reacted with HBF4 in the presence of L to give first [{(η5-C5Me5)Rh(μ-CH2)}2(Me)(L)]+ and then [{(η5-C5Me5)Rh(μ-CH2)}2(L)2]2+ (L = MeCN, CO, etc.). The {(η5-C5Me5)Rh(μ-CH2)}2 core is rather kinetically inert and also forms a variety of complexes with oxy-ligands, both cis-, e.g. [{(η5-C5Me5)Rh(μ-CH2)}2(μ-OAc)]+ and trans-, such as [(η5-C5Me5)Rh(μ-CH2)}2(H2O)2]2+. The complexes [{(η5-C5Me5)Rh(μ-CH2)}2(R)L]+ (R = Me or aryl) in the presence of CO, or [{(η5-C4Me5)Rh(μ-CH2)}2(R)2] (R = Me, Ph or CO2Me) in the presence of mild oxidants, readily yield the C---C---C coupled products RCH=CH2. The mechanisms of these couplings have been elucidated by detailed labelling studies: they are more complex than expected, but allow direct analogies to be drawn to C---C couplints that occur during Fischer-Tropsch reactions on rhodium surfaces.  相似文献   

3.
Treatment of [Ru2(CO)4(MeCN)6][BF4]2 or [Ru2(CO)4(μ-O2CMe)2(MeCN)2] with uni-negative 1,1-dithiolate anions via potassium dimethyldithiocarbamate, sodium diethyldithiocarbamate, potassium tert-butylthioxanthate, and ammonium O,O′-diethylthiophosphate gives both monomeric and dimeric products of cis-[Ru(CO)22-(SS))2] ((SS)=Me2NCS2 (1), Et2NCS2 (2), tBuSCS2 (3), (EtO)2PS2 (4)) and [Ru(CO)(η2-(Me2NCS2))(μ,η2-Me2NCS2)]2 (5). The lightly stabilized MeCN ligands of [Ru2(CO)4(MeCN)6][BF4]2 are replaced more readily than the bound acetate ligands of [Ru2(CO)4(μ-O2CMe)2(MeCN)2] by thiolates to produce cis-[Ru(CO)22-(SS))2] with less selectivity. Structures 1 and 5 were determined by X-ray crystallography. Although the two chelating dithiolates are cis to each other in 1, the dithiolates are trans to each other in each of the {Ru(CO)(η2-Me2NCS2)2} fragment of 5. The dimeric product 5 can be prepared alternatively from the decarbonylation reaction of 1 with a suitable amount of Me3NO in MeCN. However, the dimer [Ru(CO)(η2-Et2NCS2)(μ,η2-Et2NCS2)]2 (6), prepared from the reaction of 2 with Me3NO, has a structure different from 5. The spectral data of 6 probably indicate that the two chelating dithiolates are cis to each other in one {Ru(CO)(η2-Et2NCS2)2}fragment but trans in the other. Both 5 and 6 react readily at ambient temperature with benzyl isocyanide to yield cis-[Ru(CO)(CNCH2Ph)(η2-(SS))2] ((SS)=Me2NCS2 (7) and Et2NCS2 (8)). A dimerization pathway for cis-[Ru(CO)22-(SS))2] via decabonylation and isomerization is proposed.  相似文献   

4.
Activation volumes for aquation of cis-[Co(en)2(NO2)Cl]+, trans-[Co(en)2 (CN)Cl]+, cis-- and cis-β-[Co(trien)Cl2]+ have been determined, and are compared with values reported for a range of chloroaminecobalt(III) complexes. Variation of reported ΔV in terms of, particularly, solvation effects is discussed.  相似文献   

5.
Reaction of cis-[Ptph2(SMe2)2] with Me2PCH2PMe2 (dmpm) gave cis-[PtPh2(dmpm-P)2] (1) or cis,cis-[Pt2Ph4(μ-dmpm)2] (2) and reaction of 1 with [Pt2Me4(μ-SMe2)2] gave cis,cis-[Ph2Pt(μ-dmpm)2PtMe2] (3). Reaction of 1 with trans-[PtClR(SMe2)2] gave cis,trans-[Ph2Pt(μ-dmpm)2PtClR], R = Me (5) or Ph (6), and in polar solvents, these isomerized to give [Ph2Pt(μ-dmpm)2PtR]+Cl. When R = Me, further isomerization via the phenyl group transfer gave [PhMePt(μ-dmpm)2PtPh]+Cl. Oxidative addition of methyl iodide occurred reversibly at the cis-[PtMe2P2 unit of 3 to give cis,fac-[Ph2Pt(μ-dmpm)2PtIMe3] but complex 2 failed to react with MeI. A comparison with similar known complexes of Ph2PCH2PPh2 (dppm) is made and differences are attributed primarily to the lower steric hindrance of dmpm.  相似文献   

6.
The reaction of trans-X(CO)4WCNR2 (X = Br, R = c hex (cyclohexyl); X = Cl, R = c hex, ipr (isopropyl) with M+X (M+ = NEt4+, X = Br; M+ = PPN+, X = Cl) leads under substitution of one CO ligand to new anionic dihalo(tricarbonyl)carbyne-tungsten complexes of the type M+ mer-[(X)2(CO)3WCNR2] (M+ = NEt4+, X = Br, R = c hex; M+ = PPN+, X = Cl, R = c hex, i pr), whose composition and structure were determined by elemental analysis as well as by IR, 1H and 13C NMR spectroscopy. In the anionic carbyne complexes the entered halogen ligand, coordinated in a cis position relative to the carbyne ligand on the metal, can be easily substituted by neutral nucleophiles, as the reaction of PPN+ mer-[(Cl)2(CO)3WCNchex2] with PPh3 demonstrates yielding the neutral carbyne complex mer-[Cl(CO)3(PPh3)WCNchex2].  相似文献   

7.
The reactions of a wide range of transition-metal carbonyls with anhydrous HF are described. In particular, Ru3(CO)12, Os3(CO)12 and Ir4(CO)12 give the solution stable [Ru3(CO)12H]+, [Ru(CO)5H]+, [Os3(CO)12H]+, [Os(CO)5H]+ and [Ir4(CO)12H2]2+ respectively, which have been characterised by a combination of 1H and 13C NMR spectroscopy.  相似文献   

8.
Complexes of the types (a) trans- and cis-[Pd(C6X5)2 (CNR)2], (b) trans- [Pd(C6X5)Cl(CNR)2] and (c) [Pd(C6X5)(CNR)3]ClO4 (X = F or Cl;R = But cyclohexyl or p-tolyl) have been made by replacement of the tetrahydrothiophen or Cl groups of appropriate precursors by isonitrile. Their structures have been assigned on the basis of their IR and 1H NMR spectra.  相似文献   

9.
Aldol-type reactions of trimethylsilyl enol ethers with acetals, ketals, and orthoesters are successfully performed with the aid of a catalytic amount of rhodium complex, Rh4(CO)12 or [Rh(COD)(DPPB)]+ClO4, underneutral conditions.  相似文献   

10.
Miho Fujita  R. D. Gillard 《Polyhedron》1988,7(24):2731-2742
Stable aqueous solutions of the green ion [Co(sa1)3]3− (sa1 = dianion, C6H4( )(CO ), of salicylic acid, 2-hydroxybenzoic acid) are obtained from [Co(NH3)5 C1]C12 and an excess of salicylic acid. Several salts, [C][Co(sa1)3] have been characterized, where C = [Co(NH3)6]3+ and [M(en)3]3+ (M = Co or Rh, EN = 1,2-diamino-ethane). By using (+)-[Rh(en)3]3+, optical resolution via less soluble diastereoisomeric salts has been achieved, and isomerization and racemization have been studied. Resolved tris-malonatocobaltate(III) has been used as a model. A novel thermochromism (77-293 K) in solid Δ(+)-[Rhen3]Λ[Co(sa1)3 is described.  相似文献   

11.
Toma HE  Sernaglia RL 《Talanta》1995,42(12):1867-1874
The electrochemical and spectroelectrochemical behavior of the binuclear and trinuclear complexes generated from the association of cis- or trans-[Ru(NH3)4(pz)2]3+/2+ (where pz represents pyrazine) and [RuEDTA(H2O)]2−/− complexes has been investigated in aqueous solution. Based on two sets of spectrophotometrically determined equilibrium constants and on the formal redox potentials, the complex network of equilibrium reactions involving mixed valence species has been elucidated.  相似文献   

12.
Reaction of phenyl magnesium bromide with the ,β-unsaturated ketone 3-methyl-2,3,4,5,6,7-hexahydroind-8(9)-en-1-one, followed by an aqueous work-up, generates the pro-chiral tetra-substituted cyclopentadiene, 1-phenyl-3-methyl-4,5,6,7-tetrahydroindene, CpH, a precursor to the η5-cyclopentadienyl ligand in (Cp)2Fe and [(Cp)Fe(CO)]2(μ-CO)2. Both complexes were generated as mixtures of rac-(RR and SS)- and meso-(RS)-isomers, and in either case pure meso-isomer was isolated by crystallisation and characterised by single crystal X-ray structure, both molecules having crystallographic Ci symmetry. Reduction with Na/Hg cleaves meso-(RS)-[(Cp)Fe(CO)]2(μ-CO)2 and the resulting mixture of (R)- and (S)-[(Cp)Fe(CO)2] anions reacts with MeI to give racemic (Cp)Fe(CO)2Me, which was characterised by the X-ray crystal structure. The Cp ligand is more electron donating than (η-C5H5) as revealed by the reduction potential of the (Cp)2Fe+/(Cp)2Fe couple, E°=−0.127 V (vs. Ag  AgCl). Reaction of LiCp with ZrCl4 yields the zirconocene dichloride [Zr(Cp)2Cl2] as mixture of rac- and meso-isomers, from which pure rac-isomer is obtained as a mixture of RR and SS crystals by recrystallisation. The reaction of rac-[Zr(Cp)2Cl2] with LiMe gives rac-[Zr(Cp)2Me2]. The structures of RR-[Zr(Cp)2Cl2] and rac-[Zr(Cp)2Me2] have been determined by X-ray diffraction. The structural studies reveal the influence of the bulky substituted cyclopentadienyl ligand on the metal---Cp distances and other metric parameters.  相似文献   

13.
The compound [RU332- -ampy)(μ3η12-PhC=CHPh)(CO)6(PPh3)2] (1) (ampy = 2-amino-6-methylpyridinate) has been prepared by reaction of [RU3(η-H)(μ32- ampy) (μ,η12-PhC=CHPh)(CO)7(PPh3)] with triphenylphosphine at room temperature. However, the reaction of [RU3(μ-H)(μ3, η2 -ampy)(CO)7(PPh3)2] with diphenylacetylene requires a higher temperature (110°C) and does not give complex 1 but the phenyl derivative [RU332-ampy)(μ,η 12 -PhC=CHPh)(μ,-PPh2)(Ph)(CO)5(PPh3)] (2). The thermolysis of complex 1 (110°C) also gives complex 2 quantitatively. Both 1 and 2 have been characterized by0 X-ray diffraction methods. Complex 1 is a catalyst precursor for the homogeneous hydrogenation of diphenylacetylene to a mixture of cis- and trans -stilbene under mild conditions (80°C, 1 atm. of H2), although progressive deactivation of the catalytic species is observed. The dihydride [RU3(μ-H)232-ampy)(μ,η12- PhC=CHPh)(CO)5(PPh3)2] (3), which has been characterized spectroscopically, is an intermediate in the catalytic hydrogenation reaction.  相似文献   

14.
The Monsanto acetic acid process is one of the most effective ways to produce acetic acid industrially. This process has been studied experimentally but theoretical investigations are so far sparse. In the current work the active catalytic species [Rh(CO)2I2] (1) and its isomerisation has been studied theoretically using the hybrid B3LYP exchange and correlation functional. Similar calculations has been performed for the iridium complex [Ir(CO)2I2] (2) that also is catalytically active in the methanol carbonylation. Experimental work has confirmed the existence of the cis forms of the active catalytic species, but they do not rule out the possibility of the trans isomers. Our gas phase results show that cis-1 has 4.95 kcal/mol lower free energy than trans-1, and cis-2 has 10.39 kcal/mol lower free energy than trans-2. In the case of rhodium, trans-1 can take part to the catalytic cycle but in case of iridium this is not very likely. We have also investigated the possible mechanisms of the cis to trans conversions. The ligand association mechanism gave free energy barrier of 13.7 kcal/mol for the rhodium complex and 19.8 kcal/mol for iridium. Thus the conversion for the rhodium complex is feasible whereas for iridium it is unlikely.  相似文献   

15.
The synthesis and characterization of a number of new coordination compounds of PdII with the nitrogen donor 1-tert-butylpyrazole (tBuPzH) are described. Compounds are trans-[Pd(tBuPzH)2Cl2] and the cyclometallated structures [Pd2(tBuPz)2(AcO)2] and [Pd3(tBuPz)2(AcO)4]. All these complexes are mixtures of syn and anti isomers. Also, the chloro-bridged complex [Pd2(tBuPz)2Cl2] has been isolated as an equilibrium mixture of cis and trans isomers. The compounds have been studied by variable temperature 1H- and 13C-NMR spectroscopy.  相似文献   

16.
The reaction of the anionic mononuclear rhodium complex [Rh(C6F5)3Cl(Hpz)]t- (Hpz = pyrazole, C3H4N2) with methoxo or acetylacetonate complexes of Rh or Ir led to the heterodinuclear anionic compounds [(C6F5)3Rh(μ-Cl)(μ-pz)M(L2)] [M = Rh, L2 = cyclo-octa-1,5-diene, COD (1), tetrafluorobenzobarrelene, TFB (2) or (CO)2 (4); M = Ir, L2 = COD (3)]. The complex [Rh(C6F5)3(Hbim)] (5) has been prepared by treating [Rh(C6F5)3(acac)] with H2bim (acac = acetylacetonate; H2bim = 2,2′-biimidazole). Complex 5 also reacts with Rh or Ir methoxo, or with Pd acetylacetonate, complexes affording the heterodinuclear complexes [(C6F5)3Rh(μ-bim)M(L2)] [M = Rh, L2 = COD (6) or TFB (7); M = Ir, L2 = COD (8); M = Pd, L2 = η3-C3H5 (9)]. With [Rh(acac)(CO)2], complex 5 yields the tetranuclear complex [{(C6F5)3Rh(μ-bim)Rh(CO)2}2]2−. Homodinuclear RhIII derivatives [{Rh(C6F5)3}2(μ-L)2]·- [L2 = OH, pz (11); OH, StBu (12); OH, SPh (13); bim (14)] have been obtained by substitution of one or both hydroxo groups of the dianion [{Rh(C6F5)3(μ-OH)}2]2− by the corresponding ligands. The reaction of [Rh(C6F5)3(Et2O)x] with [PdX2(COD)] produces neutral heterodinuclear compounds [(C6F5)3Rh(μ-X)2Pd(COD)] [X = Cl (15); Br (16)]. The anionic complexes 1–14 have been isolated as the benzyltriphenylphosphonium (PBzPh3+) salts.  相似文献   

17.
Pentacarbonyl-rhenate and -manganate react with the cationic complexes [cpMo(CO)2(diene)]+, [cpMo(CO)2(cyclopentadiene]+, [cpMo(CO)2(cyclohexadiene)]+, [cpMo(CO)2(trimethylenemethane]+, [(OC)3Mo(η7-C7H7)]+, [cp(OC)-(Ph3P)Mo(alkyne)]+ to give the corresponding heteronuclear hydrocarbon-bridged complexes.  相似文献   

18.
In the reaction of cis-(CO)4(SnPh3)Re[C(OEt)NR2] (R = ipr (isopropyl), chex (cyclohexyl)) with BI3 the Lewis acid attacks the triphenylstannyl ligand. Substitution of a phenyl for a iodine group leads to equilibrium mixtures of rhenium carbene complexes of general formula cis-(CO)4(SnPh3−χIχ)Re[C(OEt)NR2] (χ = 1−3; R = ipr, chex). By changing the solvent and ratio of can be shifted such that only one major product is formed. Thus this reaction pathway can be used for the preparation of cis-(CO)4(SnPhI2)Re[C(OEt)NR2] (R = ipr, chex). Even when a large excess of BI3 is present electrophilic attack by the Lewis acid on the carbene ligand is not observed.

Synthesis of cis-(CO)4(SnPh3−χIχ)Re[C(OEt)NR2] (χ = 1−3; R --- ipr, chex) can be achieved in high yield by reaction of cis-(CO)4(SnPh3)Re[C(OEt)NR2] (R = ipr, chex) with one, two or three equivalents of HI. This reaction, with successive rupture of the tin-carbon bonds in the triphenylstannyl ligand and the simultaneous formation of benzene, affords the desired substitution product irreversibly. Reaction of cis-(CO)4(SnPh3)Re[C(OEt)NR2] (R = ipr, chex) with I2 gives the compounds, cis-(CO)4(SnI3)Re[C(OEt)NR2] (R = ipr, chex), in relatively low yields.  相似文献   


19.
Treatment of [Pd{CH2C(CH3)CH2}(Ph2PPy)Cl] (Ph2PPy = 2-(diphenylphosphino)pyridine) with cis-[Pd(tBuNC)2Cl2] in dichloromethane affords the mixed isocyanide-tertiary phosphine complex cis-[Pd(tBuNC)Ph2PPy)Cl2], in which the Ph2PPy is a monodentate P-donor, and [{Pd[CH2C(CH3)CH2]Cl}2]. The steric effects of the Ph2PPy bridging ligand in determining the reaction course is discussed. The complex cis-[Pd(tBuNC)(Ph2PPy)Cl2] was crystallographically characterized: P21/n, a = 15.143(2), b = 9.527(1), c = 17.517(4) Å, β = 113.96(1)°, V= 2309.4(7) Å3, Z = 4. The final R value was 0.044, Rw= 0.046 for the 3078 reflections with I > 3σ(I).  相似文献   

20.
[H(DMSO)2][trans-RuCl4(DMSO)2] (1) reacts with 2,2′-bipyridine in ethanol at room temperature resulting in the formation of a major compound, mer-[RuCl3(DMSO)(bpy)] (bpy = 2,2′-bipyridine) 3 and a known minor compound, cis-[RuCl2(DMSO)4] (4). The compounds 3 and 4 are formed via an anticipated intermediate mer-[RuCl3(DMSO)3] (2). The reaction of 3 and mer-[RuCl3(TMSO)(bpy)] (5) with small molecules like imidazole, carbon monoxide and KSCN yield, mer-[RuCl3(bpy)(im)] · 2DMSO (im = imidazole) (6) and cis-[RuCl2(TMSO)(CO)(bpy)] (7), cis-[RuCl2(DMSO)(CO)(bpy)] (8) and K[RuCl3(bpy)(SCN)] (9), respectively. The formations of 3, 6 and 7 have been authenticated by single crystal structure determinations. Compound 6 is formed by the substitution of DMSO or TMSO from 3 and 5, respectively, whereas 7 and 8 are formed by unprecedented one-electron reductions of 5 and 3. The reactions of 3 and 5 with KSCN resulted in the same compound, K[RuCl3(NCS)(bpy)] (9). DFT calculations were performed to distinguish whether the thiocyanate ligand is bound to ruthenium through S or N. In the ruthenium bipyridine systems, the HOMO contains ruthenium d-orbitals and the LUMO is typically π*-orbitals of the bipyridine ring. Complexes 3, 6 and 7 are redox active in acetone and DMSO solvent showing prominent a reduction peak and corresponding oxidation peak.  相似文献   

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