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1.
Reactions of [(PPh 3) 2Pt(η 3-CH 2CCPh)]OTf with each of PMe 3, CO and Br − result in the addition of these species to the metal and a change in hapticity of the η 3-CH 2CCPh to η 1-CH 2CCPh or η 1-C(Ph)=C=CH 2. Thus, PMe 3 affords [(PMe 3) 3Pt(η 1-C(Ph)=C=CH 2)] +, CO gives both [ trans-(PPh 3) 2Pt(CO)(η 1-CH 2CCPh)] + and [ trans-(PPh 3) 2Pt(CO)(η 1-C(Ph)=C=CH 2)] +, and LiBr yields cis-(PPh 3) 2PtBr(η 1-CH 2CCPh), which undergoes isomerization to trans-(PPh 3) 2PtBr(η 1-CH 2CCPh). Substitution reactions of cis- and trans-(PPh 3) 2PtBr(η 1-CH 2CCPh) each lead to tautomerization of η 1-CH 2CCPh to η 1-C(Ph)=C=CH 2, with trans-(PPh 3) 2PtBr(η 1-CH 2CCPh) affording [(PMe 3) 3Pt(η 1-C(Ph)=C=CH 2)] + at ambient temperature and the slower reacting cis isomer giving [ trans-(PPh 3)(PMe 3) 2Pt(η 1-C(Ph)=C=CH 2)] + at 54 °C . All new complexes were characterized by a combination of elemental analysis, FAB mas spectrometry and IR and NMR ( 1H, 13C{ 1H} and 31P{ 1H}) spectroscopy. The structure of [(PMe 3) 3Pt(η 1-C(Ph)=C=CH 2)]BPh 4·0.5MeOH was determined by single-crystal X-ray diffraction analysis. 相似文献
2.
Oxygenation of [Cu II(fla)(idpa)]ClO 4 (fla=flavonolate; IDPA=3,3′-iminobis( N, N-dimethylpropylamine)) in dimethylformamide gives [Cu II(idpa)( O-bs)]ClO 4 ( O-bs= O-benzoylsalicylate) and CO. The oxygenolysis of [Cu II(fla)(idpa)]ClO 4 in DMF was followed by electronic spectroscopy and the rate law −d[{Cu II(fla)(idpa)}ClO 4]/d t= kobs[{Cu II(fla)(idpa)}ClO 4][O 2] was obtained. The rate constant, activation enthalpy and entropy at 373 K are kobs=6.13±0.16×10 −3 M −1 s −1, Δ H‡=64±5 kJ mol −1, Δ S‡=−120±13 J mol −1 K −1, respectively. The reaction fits a Hammett linear free energy relationship and a higher electron density on copper gives faster oxygenation rates. The complex [Cu II(fla)(idpa)]ClO 4 has also been found to be a selective catalyst for the oxygenation of flavonol to the corresponding O-benzoylsalicylic acid and CO. The kinetics of the oxygenolysis in DMF was followed by electronic spectroscopy and the following rate law was obtained: −d[flaH]/d t= kobs[{Cu II(fla)(idpa)}ClO 4][O 2]. The rate constant, activation enthalpy and entropy at 403 K are kobs=4.22±0.15×10 −2 M −1 s −1, Δ H‡=71±6 kJ mol −1, Δ S‡=−97±15 J mol −1 K −1, respectively. 相似文献
3.
The stability constants of the 1:1 complexes formed between Cu(Arm) 2+, where Arm = 2,2′-bipyridyl or 1,10-phenanthroline, and methyl phosphate, CH 3OPO 32−, or hydrogen phosphate, HOPO 32−, were determined by potentiometric pH titration in aqueous solution (25°C; l = 0.1 M, NaNO 3). On the basis of previously established log K versus p Ka straight-line plots (D. Chen et al., J. Chem. Soc., Dalton Trans. (1993) 1537–1546) for the complexes of simple phosphate monoesters and phosphonate derivatives, R-PO 32−, where R is a non-coordinating residue, it is shown that the stabilities of the Cu(Arm) (CH 3OPO 3) complexes are solely determined by the basicity of the -PO 32− residue. In contrast, the Cu(Arm) (HOPO 3) complexes are slightly more stable (on average by 0.15 log unit) than expected on the basicity of HPO 42−; this is possibly due to a more effective solvation including hydrogen bonding, an interaction not possible with coordinated CH 3OPO 32− species. Regarding biological systems the observation that HOPO 32− is somewhat favored over R-PO 32− species in metal ion interactions is meaningful. 相似文献
4.
The complex Pt(bph) (CO) 2 crystallizes in the space group Cmcm with a = 18.647(6), B = 9.566(2) and C = 6.4060(5) Å. The geometry of the molecule is slightly distorted from square planar with a Pt---C(CO) bond distance of 1.98(2) Å and a Pt---C(bph) bond distance of 2.04(2) Å. The Pt(bph)(CO) 2 complex serves as a precursor for the preparation of a wide variety of Pt(bph)X 2 complexes, where X = monodentate ligands such as acetonitrile, pyridine, etc., and X 2 = bidentate ligands such as bypyridine, 1,10-phenanthroline, etc. In the solid state, the complex exhibits a green color, but when ground with an alkali metal salt turns deep blue to purple. In CH 2Cl 2, the color disappears but optical transitions are observed at 271 nm (2.7 × 10 4 M −1 cm −1), 303 nm (1.1 × 10 4 M −1 cm −1) and 330 nm (5.5 × 10 3 M −1 cm −1). The complex is a weak emitter exhibiting a structured spectrum in CH 2Cl 2 at r.t. with maxima located at 562 and 594 nm and an emission lifetime of 3.1 μs when excited at 337 nm. 相似文献
5.
[Fe(TIM)(CH 3CN) 2](PF 6) 2 (1) (TIM = 2,3,9,10-tetramethyl-1,4,8,11-tetraazacyclodeca-1,3,8,10-tetraene) forms a complex with NO reversibly in CH 3CN (53±1% converted to the NO complex) or 60% CH 3OH/40% CH 3CN (81±1% conversion). Quantitative NO complexation occurs in H 2O or CH 3OH solvents. The EPR spectrum of [Fe(TIM)(solvent)NO] 2+ in frozen 60/40 CH 3OH/CH 3CN at 77 K shows a three line feature at g=2.01, 1.99 and 1.97 of an S=1/2FeNO 7 ground state. The middle line exhibits a three-line N-shf coupling of 24 G indicating a six-coordinate complex with either CH 3OH or CH 3CN as a ligand trans to NO. In H 2O [Fe(TIM)(H 2O) 2] 2+ undergoes a slow decomposition, liberating 2,3-butanedione, as detected by 1H NMR in D 2O, unless a π-acceptor axial ligand, L=CO, CH 3CN or NO is present. An equilibrium of 1 in water containing CH 3CN forms [Fe(TIM)(CH 3CN)(H 2O)] 2+ which has a formation constant KCH3CN=320 M −1. In water KNOKCH3CN since NO completely displaces CH 3CN. [Fe(TIM)(CH 3CN) 2] 2+ binds either CO or NO in CH 3CN with KNO/ KCO=0.46, sigificantly lower than the ratio for [Fe II(hemes)] of 1100 in various media. A steric influence due to bumping of β-CH 2 protons of the TIM macrocycle with a bent S=1/2 nitrosyl as opposed to much lessened steric factors for the linear Fe---CO unit is proposed to explain the lower KNO/ KCO ratio for the [Fe(TIM)(CH 3CN)] 2+ adducts of NO or CO. Estimates for formation constants with [Fe(TIM)] 2+ in CH 3CN of KNO=80.1 M −1 and KCO=173 M − are much lower than to hemoglobin (where KNO=2.5×10 10 M −1 and KCO=2.3×10 7) due to a reversal of steric factors and stronger π-backdonation from [Fe II(heme)] than from [Fe II(TIM)(CH 3CN)] 2+. 相似文献
6.
A new functional macrocyclic ligand, 2,4-dinitrophenylcyclen (= 1-(2,4-dinitrophenyl)-1,4,7,10-tetraazacyclododecane), has been synthesized and isolated as its trihydrochloric acid salt (L·3HCl). The protonation constants (log Kn) for three secondary nitrogens of L were determined by potentiometric pH titration to be 10.10, 7.33 and <2 with I = 0.10 (NaNO 3) at 25°C. The 2,4-dinitrophenylaniline chromophore was proven to be a good reporter signaling proton- and metal-binding events in the macrocyclic cavity. The UV absorption band (λ max 370 nm, 8200) of the 2,4-dinitrophenylaniline moiety at pH ≥ 9 becomes quenched as pH is lowered (to pH 3.1, where the major species is L·2H +), due to the strong protonation effect extended to the aniline moiety within the macrocyclic cavity. This is in sharp contrast to the pH-independent UV absorption (λ max 390 nm, 14 000) of a reference compound, N,N-diethyl-2,4-dinitroaniline. The UV absorption band of L is shifted to lower wavelengths with Zn 2+ (λ max 320 nm), Cd 2+ (λ max 316 nm) and Pb 2+ (λ max 317 nm), while it almost disappears with Cu 2+ and Ni 2+. The 1:1 Zn 2+ and Cu 2+ complexes with L were isolated and characterized. The Zn 2+ complex recognizes 1-methylthymine anion (MT −) in aqueous solution at physiological pH to yield a stable ternary complex ZnL-MT −. The X-ray crystal structure of ZnL-MT − showed that Zn 2+ is four-coordinate with three secondary nitrogens of L and the deprotonated imide anion that is cofacial to the 2,4-dinitrophenyl ring. 相似文献
7.
Copper(II) complexes were synthesized and characterized by means of elemental analysis, IR and visible spectroscopies, EPR and electrochemistry, as well as X-ray structure crystallography. The group consists of discrete mononuclear units with the general formula [Cu(II)(Hbpa) 2](A) 2· nH 2O, where Hbpa=(2-hydroxybenzyl-2-pyridylmethyl)amine and A=ClO 4 −, n=2 (1), CH 3COO −, n=3 (2), NO 3 −, n=2 (3) and SO 4 2−, n=3 (4). The structures of the ligand Hbpa and complex 1 have been determined by X-ray crystallography. Complexes 1–4 have had their UV–Vis spectra measured in both MeCN and DMF. It was observed that the compounds interact with basic solvents, such that molecules coordinate to the metal in axial positions in which phenol oxygen atoms are coordinated in the protonated forms. The values were all less than 1000 M −1 cm −1. EPR measurements on powdered samples of 1–3 gave g/ A values between 105 and 135 cm −1, typical for square planar coordination environments. Complex 4·3H 2O exhibits a behaviour typical for tetrahedral coordination. The electrochemical behaviour for complexes 1 and 2 was studied showing irreversible redox waves for both compounds. 相似文献
8.
The reaction of ReH 92− with Mo(diglyme)(CO) 3 leads to the formation of the mixed metal cluster trianion, ReMo 3H 4(CO) 123−. This species has been characterized analytically, spectroscopically and through X-ray diffraction analysis. A pseudo-tetrahedral arrangement of M(CO) 3 fragments is adopted, such that each set of three carbonyl ligands eclipses the adjacent three tetrahedral edges, an apparent result of the location of the hydride ligands on the tetrahedral faces. Variable temperature NMR studies revealed a fluctional process for some of the carbonyl ligands, but not for the hydrides. Crystal data for [Me 4N] 3[ReMo 3H 4(CO) 12]·THF; space group P2 1/ n, a = 12.157(2), B = 21.480(4), C = 15.964(3) Å, β = 98.26(1)°, Z = 4, R = 0.067 and Rw = 0.076. 相似文献
9.
Treatment of the A-ring aromatic steroids estrone 3-methyl ether and β-estradiol 3, 17-dimethyl ether with Mn(CO) 5+BF 4− in CH 2Cl 2 yields the corresponding [(steroid)Mn(CO) 3]BF 4 salts 1 and 2 as mixtures of and β isomers. The X-ray structure of [(estrone 3-methyl ether)Mn(CO) 3]BF 4 · CH 2Cl 2 (1) having the Mn(CO) 3 moiety on the side of the steroid is reported: space group P2 1 with a=10.3958(9), b=10.9020(6), c=12.6848(9) Å, β=111.857(6)°, Z=2, V=1334.3(2) Å 3, calc=.481 cm −3, R=0.0508, and wR=0.0635. The molecule has the traditional ‘piano stool’ structure with a planar arene ring and linear Mn---C---O linkages. The nucleophiles NaBH 4 and LiCH 2C(O)CMe 3 add to [(β-estradiol 3,17-dimethyl ether)Mn(CO) 3]BF 4 (2) in high yield to give the corresponding - and β-cyclohexadienyl manganese tricarbonyl complexes (3). The nucleophiles add meta to the arene -OMe substituent and exo to the metal. The and β isomers of 3 were separated by fractional crystallization and the X-ray structure of the β isomer with an exo-CH 2C(O)CMe 3 substituent is reported (complex 4): space group P2 12 12 1 with a=7.5154(8), b=15.160(2), c=25.230(3) Å, Z=4, V=2874.4(5) Å 3, calc=1.244 g cm −3, R=0.0529 and wR2=0.1176. The molecule 4 has a planar set of dienyl carbon atoms with the saturated C(1) carbon being 0.592 Å out of the plane away from the metal. The results suggest that the manganese-mediated functionalization of aromatic steroids is a viable synthetic procedure with a range of nucleophiles of varying strengths. 相似文献
10.
The phosphinoalkenes Ph 2P(CH 2) nCH=CH 2 ( n= 1, 2, 3) and phosphinoalkynes Ph 2P(CH 2) n C≡CR (R = H, N = 2, 3; R = CH 3, N = 1) have been prepared and reacted with the dirhodium complex (η−C 5H 5) 2Rh 2(μ−CO) (μ−η 2−CF 3C 2CF 3). Six new complexes of the type (ν−C 5H 5) 2(Rh 2(CO) (μ−η 1:η 1−CF 3C 2CF 3)L, where L is a P-coordinated phosphinoalkene, or phosphinoalkyne have been isolated and fully characterized; the carbonyl and phosphine ligands are predominantly trans on the Rh---Rh bond, but there is spectroscopic evidence that a small amount of the cis-isomer is formed also. Treatment of the dirhodium-phosphinoalkene complexes with (η−CH 3C 5H 4)Mn(CO) 2thf resulted in coordination of the manganese to the alkene function. The Rh 2---Mn complex [(η−C 5H 5) 2Rh 2(CO) (μ−η 1:η 1−CF 3C 2CF 3) {Ph 2P(CH 2) 3CH=CH 2} (η−CH 3C 5H 4)Mn(CO) 2] was fully characterized. Simi treatment of the dirhodium-phosphinoalkyne complexes with Co 2(CO) 8 resulted in the coordination of Co 2(CO) 6 to the alkyne function. The Rh 2---Co 2 complex [(η−C 5H 5) 2Rh 2(CO) (μ−η 1:η 1−CF 3C 2CF 3) {Ph 2PCH 2C≡CCH 3}Co 2(CO) 2], C 37H 25Co 2F 6O 7PRh 2, was fully characteriz spectroscopically, and the molecular structure of this complex was determined by a single crystal X-ray diffraction study. It is triclinic, space group
( Ci1, No. 2) with a = 18.454(6), B = 11.418(3), C = 10.124(3) Å, = 112.16(2), β = 102.34(3), γ = 91.62(3)°, Z = 2. Conventional R on | F| was 0.052 fo observed ( I > 3σ( I)) reflections. The Rh 2 and Co 2 parts of the molecule are distinct, the carbonyl and phosphine are mutually trans on the Rh---Rh bond, and the orientations of the alkynes are parallel for Rh 2 and perpendicular for Co 2. Attempts to induce Rh 2Co 2 cluster formation were unsuccessful. 相似文献
11.
The reactions of the polysulfur and selenium cationic clusters S 82+ and Se 82+ with various iron carbonyls were investigated. Several new chalcogen containing iron carbonyl cluster cations were isolated, depending on the nature of the counteranion. In the presence of SbF 6− as a counterion, the cluster [Fe 3(E 2) 2(CO) 10] [SbF 6] 2·SO 2 (E = S, Se) could be isolated from the reaction of E 82+ and excess iron carbonyl. The cluster is a picnic-basket shaped molecule of two iron centers linked by two Se 2 groups, with the whole fragment capped by an Fe(CO) 4 group. Crystallographic data for C 10O 12Fe 3Se 4Sb 2F 12S (I): space group monoclinic P2 1/ c, A = 11.810(9), b = 24.023(6), c = 10.853(7) Å, β = 107.15(5)°, V = 2942(3) Å 3, Z = 4, R = 0.0426, Rw = 0.0503. When Sb 2F 11− is present as the counterion, or Se 4[Sb 2F 11] 2 is used as the cluster cation source, a different cluster can be isolated, which has the formula [Fe 4(Se 2) 3(CO) 12] [SbF 6] 2·3SO 2. The dication contains two Fe 2Se 2 fragments bridged by an Se 2 group. Crystallographic data for C 12O 18Fe 4Se 6Sb 2F 12S 3 (III): space group triclinic
, b = 18.400(9), C = 10.253(4) Å, = 93.10(4), β = 103.74(3), γ = 93.98(3)°, V = 1995(1) Å 3, Z = 2, R = 0.0328, Rw = 0.0325. The CO stretches in the IR spectrum all show a large shift to higher wavenumbers, suggesting almost no τ backbonding from the metals. This also correlates with the observed bond distances. All the compounds are extremely sensitive to air and water, and readily lose SO 2 when removed from the solvent. Thus all the crystals were handled at −100°C. The clusters seem to be either insoluble or unstable in all solvents investigated. 相似文献
12.
The kinetics and equilibria of complex formation by Ga(III) with NCS − in aqueous solution have been measured over a range of acidities and temperatures, the contributing paths to the reaction resolved, and their rate constants and activation parameters determined. The hydrolysis equilibria required to carry out this resolution of kinetic behaviour have also been measured. Unlike the other reported complexation reactions of Ga(III) in aqueous solution, the separate reaction pathways can be assigned with no ambiguity. At 25 °C and ionic strength 0.5 M, the observed forward rate constant for the complex formation is described by {k1 + k2K1h/[H+] + k3K1hK2h/[H+]2} M−1 s−1. For these conditions, the first and second successive hydrolysis constants of Ga(H2O)63+ are given by pK1h = 3.69 ± 0.01 and pK2h = 3.74 ± 0.04. The rate constants corresponding to the reactions of the species Ga(H2O)63+, Ga(H2O)5(OH)2+ and Ga(H2O)4(OH)2+ with NCS− are k1 = 57 ± 4 M−1 −1, k2 = (1.08 ± 0.01) × 105 M−1 s−1 and k3 = 3 × 106 M−1 s−1 respectively. The complexation equilibrium quotient [GaNCS2+]/([Ga3+][NCS−]) has been independently determined by spectrophotometric titration to be 20.8 ± 0.3 M−1 at 25 °C and ionic strength 0.5 M. These kinetic results lead to an interpretation of the data, and a reinterpretation of other data for aquo-Ga(III) complex formation kinetics from the literature which support the assignment of a dissociative interchange mechanism for these reactions rather than the associative activation mode sometimes proposed. 相似文献
13.
1. Single reduced methyl viologen (MV .+) acts as an electron donor in a number of enzyme systems. The large changes in extinction coefficient upon oxidation (λ max 600 nm; MV .+, = 1.3 · 10 4 M −1 · cm −1; oxidised form of methyl viologen (MV 2+), = 0.0) make it ideally suited to kinetic studies of electron transfer reactions using stopped-flow and standard spectrophotometric techniques. 2. A convenient electrochemical preparation of large amounts of MV.+ has been developed. 3. A commercial stopped-flow apparatus was modified in order to obtain a high degree of anaerobicity. 4. The reaction of MV.+ with O2 produced H2O2 (k > 5 · 106 M−1 · s−1, pH 7.5, 25 °C). H2O2 subsequently reacted with excess MV.+ (k = 2.3 · 103 M−1 · s−1, pH 7.5, 25 °C) to produce water. The kinetics of this reaction were complex and have only been interpreted over a limited range of concentrations. 5. The results support the theory that the herbicidal action of methyl viologen (Paraquat, Gramoxone) is due to H2O2 (or radicals derived from H2O2) induced damage of plant cell membrane. 相似文献
14.
The complex [Et 4N][W(CO) 5OMe] (1) has been prepared from the reaction of the photochemically generated W(CO) 5THF adduct and [Et 4N][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 [Et 4N] 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 [Et 4N] 3[W 2(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 [Et 4N] 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 [Et 4N] 3[W 2(CO) 6(OCH 2CH 2OH) 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 P2 1/ 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 P2 12 12 1, 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 [Et 4N][W(CO) 5OR] (R = C 6H 5 and 3,5-F 2C 6H 3) 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
15.
The synthesis of the tetradentate pendant arm macrocycles 1,4,7-triazacyclononane- N-acetate (L 1) and N-(2-hydroxybenzyl)-1,4,7-triazacyclononane (HL 2) and their coordination chemistry with vanadium(IV) and (V) are reported. The following mononuclear species have been prepared and characterized by UV-Vis, IR spectroscopy: [L 1V IVO(NCS)] (1), [L 1VO 2]·H 2O (2), [L 2VO(NCS)] (3), [L 2VO(NCS)]Cl (4), and [L 2VO 2] (5). In addition, the dinuclear, mixed valent complexes [L 21V 2O 3]Br (6), [L 22V 2O 3](ClO 4)·0.5acetone (7), and the homovalent complex [L 22V 2O 3](ClO 4) 2 (8) have been synthesized. Complexes 2, 3, 6 and 7 have been characterized by single crystal X-ray crystallography. Crystal data: 2, space group P2 1c, a=9.944(4), b=6.701(3), c=18.207(8)Å, β=102.88(3)°, V=1182.7 Å 3, Z=4, Dcalc=1.51 g cm −3, R=0.049 based on 4760 reflections; 3, space group Pbca, A=11.003(6), b=14.295(7), C=20.21(1) Å, V=3178.8 Å 3, Z=8, Dcalc=1,50 g cm −3, R=0.057 based on 1049 reflections; 6, space Pbcn, a=12.922(3), B=13.852(3), C=12.739(3) Å, V=2280.3 Å 3, Z=4, Dcalc=1,75 g cm −3, R=0.047 based on 1172 reflections; 7, space group C2/ c, A=23.553(9), B=13.497(5), C=20.951(8) Å, β=90.03(3)°, V=6660.2 Å 3, Z=8, Dcalc=1.49 g cm −3, R=0.053 based on 3698 reflections. Complexes 6 and 7 are mixed valent V(IV)/(V) complexes containing the [OV---O---VO] 3+ core. In the solid state 6 belongs to class III (delocalized) and 7 to class I (localized) according to the Robin and Day classification of mixed valent compounds. A rationale for these differing electronic structures is given. 相似文献
16.
The enthalpies of reaction of HMo(CO) 3C 5R 5 (R = H, CH 3) with diphenyldisulfide producing PhSMo(CO) 3C 5R 5 and PhSH have been measured in toluene and THF solution (R = H, Δ H= −8.5 ± 0.5 kcal mol −1 (tol), −10.8 ± 0.7 kcal mol −1 (THF); R = CH 3, Δ H = −11.3±0.3 kcal mol −1 (tol), −13.2±0.7 kcal mol −1 (THF)). These data are used to estimate the Mo---SPh bond strength to be on the order of 38–41 kcal mol −1 for these complexes. The increased exothermicity of oxidative addition of disulfide in THF versus toluene is attributed to hydrogen bonding between thiophenol produced in the reaction and THF. This was confirmed by measurement of the heat of solution of thiophenol in toluene and THF. Differential scanning calorimetry as well as high temperature calorimetry have been performed on the dimerization and subsequent decarbonylation reactions of PhSMo(CO) 3Cp yielding [PhSMo(CO) 2Cp] 2 and [PhSMo(CO)Cp] 2. The enthalpies of reaction of PhSMo(CO) 3Cp and [PhSMo(CO) 2Cp] 2 with PPh 3, PPh 2Me and P(OMe) 3 have also been measured. The disproportionation reaction: 2[PhSMo(CO) 2Cp] 2 → 2PhSMo(CO) 3Cp + [PhSMP(CO)Cp] 2 is reported and its enthalpy has also been measured. These data allow determination of the enthalpy of formation of the metal-sulfur clusters [PhSMo(CO) nC 5H 5] 2, N = 1,2. 相似文献
17.
Carbonylation of the anionic iridium(III) methyl complex, [MeIr(CO) 2I 3] − (1) is an important step in the new iridium-based process for acetic acid manufacture. A model study of the migratory insertion reactions of 1 with P-donor ligands is reported. Complex 1 reacts with phosphites to give neutral acetyl complexes, [Ir(COMe)(CO)I 2L 2] (L = P(OPh) 3 (2), P(OMe) 3 (3)). Complex 2 has been isolated and fully characterised from the reaction of Ph 4As[MeIr(CO) 2I 3] with AgBF 4 and P(OPh) 3; comparison of spectroscopic properties suggests an analogous formulation for 3. IR and 31P NMR spectroscopy indicate initial formation of unstable isomers of 2 which isomerise to the thermodynamic product with trans phosphite ligands. Kinetic measurements for the reactions of 1 with phosphites in CH 2Cl 2 show first order dependence on [1], only when the reactions are carried out in the presence of excess iodide. The rates exhibit a saturation dependence on [L] and are inhibited by iodide. The reactions are accelerated by addition of alcohols (e.g. 18× enhancement for L = P (OMe) 3 in 1:3 MeOH-CH 2Cl 2). A reaction mechanism is proposed which involves substitution of an iodide ligand by phosphite, prior to migratory CO insertion. The observed rate constants fit well to a rate law derived from this mechanism. Analysis of the kinetic data shows that k1, the rate constant for iodide dissociation, is independent of L, but is increased by a factor of 18 on adding 25% MeOH to CH 2Cl 2. Activation parameters for the k1 step are Δ H≠ = 71 (±3) kJ mol −, Δ S≠ = −81 (±9) J mol −1 K −1 in CH 2Cl 2 and Δ H≠ = 60(±4) kJ mol −1, Δ S≠ = −93(± 12) J mol −1 K −1 in 1:3 MeOH-CH 2Cl 2. Solvent assistance of the iodide dissociation step gives the observed rate enhancement in protic solvents. The mechanism is similar to that proposed for the carbonylation of 1. 相似文献
18.
The reaction of meso-tetrakis (4-dimethoxyphenyl) porphinatomanganese(II), MnTP OMeP, with TCNE (TCNE = tetracyanoethylene) leads to the formation of [MnTP OMeP] + [TCNE] − and [MnTP OMeP] +[OC(CN)C(CN) 2] −. The single-crystal X-ray structures of the latter as well as [Cu(bipy) 2Cl] + [OC(CN)C(CN) 2] − were determined. The former has a disordered [OC(CN)C(CN) 2] − bridging via C and O between a pair of Mn III sites, whereas the latter has an isolated [OC(CN)C(CN) 2] − unbound to Cu II. The IR characterization for μ 2-C,O bound [OC(CN)C(CN) 2] − is at 2219m and 2196s (νCN) cm −1 and at 1558s (νCO) cm −1 while for unbound [OC(CN)C(CN) 2] − it is at 2210m, 2203m, 2181m (νCN) cm −1 and at 1583s (νCO) cm −1. 相似文献
19.
The reactions of complex (C 5Me 5)Ir(Cl) (CO) (Me) (1a) with cyclohexylisocyanide and phosphines (L=CyNC, PHPh 2, PMePh 2, PMe 2Ph) give the products of alkyl migratory insertion (C 5Me 5Ir(Cl) (COMe) (L), in toluence or tetrahydrofuran at 323 K or higher temperature. The phenyl analogue (C 5Me 5)Ir(Cl)(CO)(Ph) or the iodide complexes (C 5Me 5)Ir(I) (CO) (R) (R=Me, Ph_are not reactive under the same conditions. The reaction of (C 5Me 5)Ir(Cl)(CO)(Me) with PMePh 2 and PMe 2Ph in acetonitrile yields the chloride substitution product [(C 5Me 5)Ir(CO)(L)(Me)] +Cl −. Kinetic measurements for the reactions of (C 5Me 5)Ir(Cl)(CO)(Me) in toluene are first order in the iridium complex and exhibit a saturation dependence on the incoming donors L. Analysis of the data suggests a two-step process involving (i) rapid formation of a molecular complex [(C 5Me 5)Ir(Cl)(CO)(Me), (L)], in which the structure of 1a is unperturbed within the limits of spectroscopic analysis, and (ii) rate determining methyl migration. The reaction parameters are K for the pre-equilibrium step ( K = 1.5 (CyNC), 7.3 (PHPh 2), 7.1 (PMePh 2) dm 3 mol −1 at 323 K) and k2 for the slow carbon---carbon bond formation ( k2 (10 5) = 6.9 (CyNC), 1.2 (PHPh 2), 1.0 (PMePh 2) s −1 at 323 K). The activation parameters for the methyl migration step in the reaction with PMePh 2 obtained between 308 and 338 K, are Δ H≠ = 106±16 kJ mol −1 and Δ S≠ = − 14±5 J K −1 mol −1. The reaction of 1a with PMePh 2 proceeds at similar rates in tetrahydrofuran ( K = 3.7 dm 3 mol −1, k2 (10 5) = 1.2 s −1, 323 K). The crystal structure of (C 5Me 5)Ir(Cl)(COMe) (PMe 2Ph) has been determined by X-ray diffraction. C 20H 29ClOPIr: Mr = 544.1, monoclinic, P2 1/ n, A = 8.084 (2), B = 9.030(2), C = 28.715 (3) Å, β = 91.41 (3)°, Z = 4, Dc = 1.71 g cm −3, V = 2095.5 Å 3, room temperatyre, Mo K, γ = 0.71069, μ = 65.55 cm −1, F(000) = 1044, R = 0.037 for 2453 independent observed reflections. The complex shows a deformed tetrahedral coordination assuming the η 5-C 5Me 5 molecular fragment as a single coordination site. The iridium-chlorine bond is staggered with respect to two adjacent C(ring)-methyl bonds, while the Ir---P and the Ir---COMe bonds are eclipsed with respect to C(ring)-methyl bonds. 相似文献
20.
The structure of [Re(CO) 3(phen)(im)] 2SO 4·4H 2O has been determined by X-ray crystallography. The yellow crystals are orthorhombic, space group Pccn (No. 56), with a=17.456(6), B=18.194(5), C=12.646(4) Å, R=0.063 for Fo2>0, R=0.032 for Fo2>3σ. The compound, which also has been characterized by IR, 1H NMR, and UV---Vis spectroscopies, exhibits room temperature luminescence in aqueous solution (τ=120 ns) as well as reversible oxidation and reduction in acetonitrile solution (1.85 and −1.30 V versus SCE). The redox properties of the excited state of the complex ( E0(Re +*/0 = 1.2; E0(Re 2+/+*) = −0.7 V) are being exploited in studies of laser-induced electron tunneling in Re(CO) 3(phen)(histidine)-modified proteins. 相似文献
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