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1.
Hlne Conjeaud  Paul Mathis 《BBA》1980,590(3):353-359
The primary donor of Photosystem II (PS II), P-680, was photo-oxidized by a short flash and its rate of reduction was measured at different pH values by following the recovery of the absorption change at 820 nm in chloroplasts pretreated with a high concentration of Tris. The re-reduction is biphasic with a fast phase (dominant after the first flash) attributed to the donation by a donor, D1, and a slow phase (usually dominant after the second flash) attributed to a back-reaction with the primary acceptor.

It is found that pH has a strong influence on the donation from D1 (τ = 2 μs at pH 9, 44 μs at pH 4), but no influence on the back reaction (τ ≈ 200 μs). pH also influences the stability of the charge separation since the contribution of donation from D1 at the second flash increases at lower pH, getting close to 100% at pH 4.  相似文献   


2.
With exposure to trace amounts of air and moisture, the Cr2(II, II) complex Cr2(μ-3,5Cl2-form)4, where 3,5Cl2-form is [(3,5-Cl2C6H3)NC(H)N(3,5-Cl2C6H3)], undergoes an oxidative addition reaction. Structural information from the X-ray crystal structure of the edge-sharing bioctahedral (ESBO) Cr2(III, III) product Cr2(μ-OH)2(μ-3,5Cl2-form)22-3,5Cl2-form)2 (1) indicates 1 has a significantly longer Cr–Cr distance [2.732(2) Å] than Cr2(μ-3,5Cl2-form)4 [1.9162(10) Å], but the shortest Cr–Cr distance in an ESBO Cr2(III, III) complex recorded to date.  相似文献   

3.
The dimetal μ-vinylidene complexes Cp(CO)2MnPt(μ-C = CHPh)L2 (L = tert.-phosphine or -phosphite), which have been obtained by coupling of the mononuclear complex Cp(CO)2Mn=C=CHPh and unsaturated PtL2 unit, add smoothly the Fe(CO)4 moiety to produce trimetal MnFePt compounds. The μ3-vinylidene cluster CpMnFePt(μ3-C=CHPh)(CO)6(PPh3) was prepared in quantitative yields from the reactions of Cp(CO)2MnPt(μ-C=CHPh)(PPh3)L (L = PPh3 or CO) with Fe2(CO)9 in benzene at 20 °C. The phosphite-substituted complexes Cp(CO)2Mnpt(μ-C=CHPh)L2 (L = P(OEt)3 or P(OPri)3) react under analogous conditions with Fe2(CO)9 to give mixtures (2:3) of the penta- and hexacarbonyl clusters, CpMnFePt(μ3-C = CHPh)(CO)5L2 and CpMnFePt(μ3-C = CHPh)(CO)6L, respectively. The similar reaction of the dimetal complex Cp(CO)2MnPt(μ-C = CHPh)(dppm), in which the Pt atom is chelated by dppm = Ph2PCH2PPhPin2 ligand, gives only a 15% yield of the analogous trimetal μ3-vinylidene hexacarbonyl product CpMnFePt(μ3-C = CHPh)(CO)(dppm), but the major product (40%) is the tetranuclear μ4-vinylidene cluster (dppm)PtFe34-C = CHPh)(CO)9. The IR and 1H, 13C and 31P NMR data for the new complexes are reported and discussed.  相似文献   

4.
The cationic monoalkylated derivatives of the well-known metalloligand [Pt2(μ-S)2(PPh3)4], viz. [Pt2(μ-S)(μ-SR)(PPh3)4]+ (R = n-Bu, CH2Ph) are themselves able to act as metalloligands towards the Ph3PAu+ and R′Hg+ (R′ = Ph or ferrocenyl) fragments, by reaction with Ph3PAuCl or R′HgCl, respectively. The resulting dicationic products [Pt2(μ-SR)(μ-SAuPPh3)(PPh3)4]2+ and [Pt2(μ-SR)(μ-SHgR′)(PPh3)4]2+ are readily isolated as their hexafluorophosphate salts, and have been fully characterised by spectroscopic techniques and an X-ray structure determination on [Pt2(μ-SR)(μ-SHgFc)(PPh3)4](PF6)2.  相似文献   

5.
Dinuclear manganese(II) complexes [Mn2(bomp)(PhCO2)2]BPh4 (1), [Mn2(bomp)(MeCO2)2]BPh4 (2), and [Mn2(bomp)(PhCO2)2]PF6 (3) were synthesized with a dinucleating ligand 2,6-bis[bis(2-methoxyethyl)aminomethyl]-4-methylphenol [H(bomp)]. Dinuclear zinc complex [Zn2(bomp)(PhCO2)2]PF6 (4) was also synthesized for the purpose of comparison. X-ray analysis revealed that the complex 1·CHCl3 contains two manganese ions bridged by the phenolic oxygen and two benzoate groups, forming a μ-phenoxo-bis(μ-benzoato)dimanganese(II) core. Magnetic susceptibility measurements of 1–3 over the temperature range 1.8–300 K indicated antiferromagnetic interaction (J=−4 to −6 cm−1). Cyclic voltammograms of 3 showed a quasi-reversible oxidation process at +0.9 V versus a saturated sodium chloride calomel reference electrode, assigned to MnIIMnII/MnIIMnIII.  相似文献   

6.
The dinuclear Pt---Si complex {(Ph3P)Pt{μ-η2-H---SiH(IMP)]}2 (trans-1a–cis-1b=3:1; IMP=2-isopropyl-6-methylphenyl) reacted with basic phosphines such as 1,2-bis(diphenylphosphino)ethane (dppe) and dimethylphenylphosphine (PMe2Ph) to afford different dinuclear Pt---Si complexes with loss of H2, {(P)2Pt[μ-SiH(IMP)]}2 [P=dppe, trans-2a (major), cis-2b (trace); PMe2Ph, 3 (trans only)]. Complexes 2 and 3 were characterized by multinuclear NMR spectroscopy and X-ray crystallography (2a). In contrast, the reaction of 1a,b with the sterically demanding tricyclohexylphosphine (PCy3) afforded {(Cy3P)Pt{μ-η2-H---SiH(IMP)]}2 (trans-4a–cis-4b 2:1) analogous to 1a,b where the central Pt2Si2(μ-H)2 core remains intact but the PPh3 ligands have been replaced by PCy3. Complexes 4a and 4b was characterized by multinuclear NMR and IR spectroscopies.  相似文献   

7.
Five heterometallic compounds with formulae [Ba(H2O)4Cr2(μ-OH)2(nta)2] · 3H2O (I), [M(bpy)2(H2O)2] [Cr2(OH)2(nta)2] · 7H2O, where M2+ = Zn, (II); Ni, (III); Co, (IV) and [Mn(H2O)3(bpy)Cr2(OH)2(nta)2] · (bpy) · 5H2O (V); bpy = 2,2′-bipyridine, (nta = nitrilotriacetate ion) have been prepared by reaction of I with the corresponding MII-sulfates in the presence of 2,2′-bipyridine. Substances I–V have been characterized by magnetic susceptibility measurements, EPR and X-ray determinations. I represents a 2D coordination polymer formed by coordination of centrosymmetrical dimeric chromium(III) units and Barium cations. The 10-coordinate Ba polyhedron is completed by four water molecules. Compounds II–IV are isostructural and consist of non-centrosymmetric dimeric anions [Cr2(μ-OH)2(nta)2]2−, complex cations [MII(bpy)2(H2O)2]2+ and solvate water molecules. The octahedral coordination of chromium atoms implies four donor atoms of the nta3− ligands and two bridging OH groups. Multiple hydrogen bonds of coordinated and solvate water molecules link anions and cations in a 3D network. A similar [Cr2(μ-OH)2(nta)2]2− unit is found in V. The bridging function is performed by a carboxylate oxygen atom of the nta ligand that leads to the formation of a trinuclear complex [Mn(bpy)(H2O)2Cr2(μ-OH)2(nta)2]. Experimental and calculated frequency and temperature dependences of EPR spectra of these compounds are presented. The fine structure appearing on the EPR spectra of compound V is analyzed in detail at different temperatures. It is established that the main part of the EPR signals is due to the transitions in the spin states of a spin multiplet with S = 2. Analyses of experimental and calculated spectra confirm the absence of interaction between metal ions (MII) and Cr-dimers in complexes III and IV and the presence of weak Mn–Cr interactions in V. The temperature dependence of magnetic susceptibilities for I–V was fitted on the basis of the expression derived from isotropic Hamiltonian including a bi-quadratic exchange term.  相似文献   

8.
9.
Metathesis of [(η33−C10H16)Ru(Cl) (μ−Cl)]2 (1) with [R3P) (Cl)M(μ-Cl)]2 (M = Pd, Pt), [Me2NCH2C6H4Pd(μ-Cl)]2 and [(OC)2Rh(μ-Cl)]2 affords the heterobimetallic chloro bridged complexes (η33-C10H16) (Cl)Ru(μ-Cl)2M(PR3)(Cl) (M = Pd, Pt), (η33-C10H16) (Cl)Ru(μ-Cl)2PdC6H4CH2NMe2 and (η33-C10H16) (Cl)Ru(μ-Cl)2Rh(CO)2, respectively. Complex 1 reacts with [Cp*M(Cl) (μ-Cl)]2 (M = Rh, Ir), [p-cymene Ru(Cl) (μ-Cl]2 and [(Cy3P)Cu(μ-Cl)]2 to give an equilibrium of the heterobimetallic complexes and of educts. The structures of (η33-C10H16)Ru(μ-Cl)2Pd(PR3) (Cl) (R = Et, Bu) and of one diastereoisomer of (η33-C10H16)Ru(μ-Cl)2IrCp*(Cl) were determined by X-ray diffraction.  相似文献   

10.
The reversible equilibrium conversion under H2 of [RuCl(dppb) (μ-Cl)]2 (1) to generate (η2-H2) (dppb) (μ-Cl)3RuCl(dppb) in CH2Cl2 (dppb = Ph2P(CH2)4PPh2) has been studied at 0–25 °C by UV-Vis and 31P{1H} NMR spectroscopy, and by stoppe kinetics; the equilibrium constant and corresponding thermodynamic parameters, and the forward and reverse rate constants at 25 °C have been determined. A measured ΔH° value of 0 kJ mol−1 allows for an estimation of an exothermicity of 60 kJ mol−1 for binding an η2-H2 at an Ru(II) centre; a ΔS° value of 60 J mol−1 K−1 indicates that in solution 1 contain s coordinated CH2Cl2. The kinetic and thermodynamic data are compared to those obtained from a previously studied hydrogenation of styrene catalyzed by 1. Preliminary findings on related systems containing Ph2P(CH2)3PPh2 and (C6H11)2P(C6H11)2 are also noted.  相似文献   

11.
Two novel, weakly antiferromagnetically coupled, tetranuclear copper(II) complexes [Cu4(PAP)22-1,1-N3)22-1,3-N3)22-CH3OH)2(N3)4 (1) (PAP = 1,4-bis-(2′-pyridylamino)phthalazine) and [Cu4(PAP3Me)22-1,1-N3)22-1,3-N3)2(H2O)2(NO2)2]- (NO3)2 (2) (PAP3Me = 1,4-bis-(3′-methyl-2′-pyridyl)aminophthalazine) contain a unique structural with two μ2-1,1-azide intramolecular bridges, and two μ2-1,3-azide intermolecular bridges linking pairs of copper(II) centers. Four terminal azide groups complete the five-coordinate structures in 1, while two terminal waters and two nitrates complete the coordination spheres in 2. The dinuclear complexes [Cu2(PPD)(μ2-1,1-N3)(N3)2(CF3SO3)]CH3OH) (3) and [Cu2(PPD)(μ2-1,1-N3)(N3)2(H2O)(ClO4)] (4) (PPD = 3,6-bis-(1′-pyrazolyl)pyridazine) contain pairs of copper centers with intramolecular μ2-1,1-azid and pyridazine bridges, and exhibit strong antiferromagnetic coupling. A one-dimensional chain structure in 3 occurs through intermolecular μ2-1,1-azide bridging interactions. Intramolecular Cu-N3-Cu bridge angles in 1 and 2 are small (107.9 and 109.4°, respectively), but very large in 3 and 4 (122.5 and 123.2°, respectively), in keeping with the magnetic properties. 2 crystallizes in the monoclinic system, space group C2/c with a = 26.71(1), b = 13.51(3), c = 16.84(1) Å, β = 117.35(3)° and R = 0.070, Rw = 0.050. 3 crystallizes in the monoclinic system, space group P21/c with a = 8.42(1), b = 20.808(9), c = 12.615(4) Å, β = 102.95(5)° and R = 0.045, Rw = 0.039. 4crystallizes in the triclinic system, space group P1, with a = 10.253(3), b = 12.338(5), c = 8.072(4) Å, = 100.65(4), β = 101.93(3), γ = 87.82(3)° and R = 0.038, Rw = 0.036 . The magnetic properties of 1 and 2 indicate the presence of weak net antiferromagnetic exchange, as indicated by the presence of a low temperature maximum in χm (80 K (1), 65 K (2)), but the data do not fit the Bleaney-Bowers equation unless the exchange integral is treated as a temperature dependent term. A similar situation has been observed for other related compounds, and various approaches to the problem will be discussed. Magnetically 3 and 4 are well described by the Bleaney-Bowers equation, exhibiting very strong antiferromagnetic exchange (− 2J = 768(24) cm−1 (3); − 2J = 829(11) cm−1 (4)).  相似文献   

12.
The reaction of TiCl4 with Li2[(SiMe2)25-C5H3)2] in toluene at room temperature afforded a mixture of cis- and trans-[(TiCl3)2{(SiMe2)25-C5H3)2}] in a molar ratio of 1/2 after recrystallization. The complex trans-[(TiCl3)2{(SiMe2)25-C5H3)2}] was hydrolyzed immediately by the addition of water to THF solutions to give trans-[(TiCl2)2(μ-O){(SiMe2)25-C5H3)2}] as a solid insoluble in all organic solvents, whereas hydrolysis of cis-[(TiCl3)2{(SiMe2)25-C5H3)2}] under different conditions led to the dinuclear μ-oxo complex cis-[(TiCl2)2)(μ-O){(SiMe2)25-C5H3)2}] and two oxo complexes of the same stoichiometry [(TiCl)2(μ-O){(SiMe2)25-C5H3)2}]2(μ-O)2 as crystalline solids. Alkylation of cis- and trans-[(TiCl3)2{(SiMe2)25-C5H3)2}] with MgCIMe led respectively to the partially alkylated cis-[(TiMe2Cl)2{(SiMe2)25-C5H3)2}] and the totally alkylated trans-[(TiMe3)2{(SiMe2)25-C5H3)2}] compounds. The crystal and molecular structure of the tetranuclear oxo complex [(TiCl)2(μ-O){(SiMe2)25-C5H3)2}]2(μ-O)2 was determined by X-ray diffraction.  相似文献   

13.
A new compound containing a cubane tungsten chalcogenide cluster [W43-Te)4(CN)12]6− and Ca2+ complex units has been prepared by the reaction of aqueous solution of K6[W43-Te)4(CN)12] · 5H2O with the solution of a Ca(NO3)2 and phen(1,10-phenanthroline) (1:2 molar ratio) in a solvent mixture of H2O/EtOH. The structure of [{Ca(phen)2(H2O)}{Ca(phen)(H2O)4}{Ca(phen)2(H2O)3}][W4Te4(CN)12] · 5H2O 1 has been determined by X-ray crystallography. Compound 1 contains [{Ca(phen)(H2O)4}{Ca(phen)2(H2O)3}][W43- Te)4(CN)12] units bridged by {Ca(phen)2(H2O)}2+ units to form an one-dimensional zigzag chain structure. Interestingly, compound 1 showed a heterogeneous catalytic activity in the transesterification of a range of esters with methanol under the mild conditions. Moreover, it can be reused without any loss of activity through 10 runs with ester.  相似文献   

14.
To determine whether centrally released vasopressin influences thirst, observations of osmotic thirst threshold, osmotic load excretion and postloading restitution of plasma osmolality were made in dogs in control experiments and during infusion of AVP antagonists into the third ventricle. Significant elevation of osmotic thirst threshold was elicited by infusion of d(CH2)5AVP at a rate of 0.2–2.0 μg·min−1 and of d(Et2)AVP at a rate of 0.3 μg·min−1 (V1 antagonists, weak V2 agonists) as well as by administration of d(CH2)5[D-Ile2,Abu4]AVP at a rate of 0.4 μg·min−1 (potent V2 antagonist, weak V1 antagonist). Administration of d(CH2)5AVP at a rate of 2.0 μg·min−1 was associated with a significant suppression of the postloading water intake and osmotic load excretion and with a delay in restitution of plasma osmolality. These findings indicate that centrally released vasopressin may participate in the control of thirst.  相似文献   

15.
The complexes RuC(CCPh)=CPhC(CCPh)=CPh(CO)3(NMe3) (3), Ru2μ-C(CCPh)=CPhC(CCPh)=CPh(CO)6 (1), Ru2μ-[C(CCPh)=CPh]2CO(CO)6 (2), Ru33-PhC2CCPh)(μ-CO)(CO)9 (4) and Ru44-PhC2CCPh)(CO)12 (5) have been isolated from reactions between PhC2C2Ph and Ru3(CO)12 or RU3(CO)10(NCMe)2. The molecular structures of complexes 1, 2, 3 and 5 have been determined from single-crystal X-ray studies. All complexes have precedents in similar products obtained from reactions involving mono-ynes; in the present cases, each alkyne fragment retains a phenylethynyl (PhCC---) group as a non-coordinated substituent.  相似文献   

16.
The dialkyl-μ-ethylidene-μ-methylene-bis (pentamethylcyclopentadienyl)-dirhodium complexes [{(C5Me5)Rh}2(μ-CH2)(μ-CHMe) (R)2] (4, P=Me; 5, Et; 6, n-Bu; 7, CH=CH2; and 8, Z-CH=CHMe) have been prepared from RMgBr and [{(C5Me5)Rh}2(μ-CH2)(μ-CHMe)(X)2] (2, X=Cl; 3, X=Br). Structures deduced from the NMR spectra show that the dialkyl complexes can exist in one trans and two cis forms. The decomposition of the dimethyl complex 4 is compared with that of the related di-μ-methylene complex; it reacts readily (30°C, MeCN solution) in the presence of one-electron oxidisers to give propene and methane and a little ethene and some butenes. Mass-spectrometric analysis of the 13C labelling in the organics originating from [{(C5Me5)Rh}2(μ-CH2)(μ-CHMe) (13CH3)2] shows that methane derives from the Rh---Me, ethene half from the ethylidene and half from coupling of Rh-methyl and a bridging methylene, while the propene arises almost entirely from the ethylidene and a rhodium methyl. The butenes come from coupling of ethylidene, methylene and a Rh-methyl, but only quite small amounts are formed; thus C+C coupling is the major decomposition path for the μ-ethylidenes, in contrast to the di-μ-methylene complexes where C+C+C coupling predominates. The divinyl complex [{(C5Me5)Rh}2(μ-CH2)(μ-CHMe) (CH=CH2)2] also underwent internal C+C coupling on reaction with AgBF4 in MeCN to give a mixture of the allyl and methylallyl cations [(C5Me5)Rh(η3-CH2CHCHR)(MeCN)]+(10, R=H; 11, R=Me).  相似文献   

17.
The Pt2 (II) isomeric terminal hydrides [(CO)(H)Pt(μ-PBu2)2Pt(PBu2H)]CF3SO3 (1a), and [(CO)Pt(μ-PBu2)2Pt(PBu2H)(H)]CF3SO3 (1b), react rapidly with 1 atm of carbon monoxide to give the same mixture of two isomers of the Pt2 (I) dicarbonyl [Pt2(μ-PBu2)(CO)2(PBu2H)2]CF3SO3 (3-Pt); the solid state structure of the isomer bearing the carbonyl ligands pseudo-trans to the bridging phosphide was solved by X-ray diffraction. A remarkable difference was instead found between the reactivity of 1a and 1b towards carbon disulfide or isoprene. In both cases 1b reacts slowly to afford [Pt2(μ-PBu2)(μ,η22-CS2)(PBu2H)2]CF3SO3 (4-Pt), and [Pt2(μ-PBu2)(μ,η22-isoprene) (PBu2H)2]CF3SO3 (6-Pt), respectively. In the same experimental conditions, 1a is totally inert. A common mechanism, proceeding through the preassociation of the incoming ligand followed by the P---H bond formation between one of the bridging P atoms and the hydride ligand, has been suggested for these reactions.  相似文献   

18.
In a search for novel analogues of β3-adrenoceptor (AR) agonists relaxing the bladder for treatment of urinary dysfunction, 2-[4-(2-{[(1S,2R)-2-hydroxy-2-(4-hydroxyphenyl)-1-methylethyl]amino}ethyl)phenoxy]-2-methylpropionic acids (1a–e), into which a fibrate-like structure had been incorporated, were synthesised. Compound 1a was found to be a selective β3-AR agonist in functional assays using the ferret detrusor (β3-AR), rat uterus (β2-AR), and rat atrium (β1-AR); β3: EC50=7.8 nM, β2: IC50=7,300 nM, β1: EC20=23,000 nM. The introduction of a chlorine atom or methyl substituent at the ortho-position on the phenyl ring of 1a further improved β3-AR selectivity. In an in vivo study, 1a lowered intrabladder pressure (ED50=31 μg/kg) in rats, without increasing heart rate, in keeping with the in vitro results. Consequently, it is proposed that 1a and its analogues (1b–e), possess β3-AR agonistic activity in the absence of undesirable β1- or β2-AR mediated actions, and may be useful for clinical treatment and pharmacological studies.  相似文献   

19.
Reactions of [Rh(COD)Cl]2 with the ligand RN(PX2)2 (1: R = C6H5; X = OC6H5) give mono- or disubstituted complexes of the type [Rh2(COD)Cl22−C6H5N(P(OC6H5)2)2}] or [RhCl{ν2−C6H5 N(P(OC6H5)2)2 }]2 depending on the reaction conditions. Reaction of 1 with [Rh(CO)2Cl]2 gives the symmetric binuclear complex, [Rh(CO)Cl{μ−C6H5N(P(OC6H5)2)2} 2, whereas the same reaction with 2 (R = CH3; X = OC6H5) leads to the formation of an asymmetric complex of the type [Rh(CO)(μ−CO)Cl{μ−CH3N(P(OC6H5)2)2}2 containing both terminal and bridging CO groups. Interestingly the reaction of 3 (R = C6H5, X = OC6H4Br−p with either [Rh(COD)Cl]2 or [Rh(CO)2Cl]2 leads only to the formation of the chlorine bridged binuclear complex, [RhCl{ν2−C6H5N(P(OC6H4Br−p)2)2}]2. The structural elucidation of the complexes was carried out by elemental analyses, IR and 31P NMR spectroscopic data.  相似文献   

20.
Analogy with the isolable oxo cluster [Fe3(CO)93-O)]2−, which is structurally interesting and synthetically useful, prompted the present attempt to synthesize its ruthenium analog. Although the high reactivity of [Ru3(CO)93-O)]2− (I) prevented its isolation, the reaction of this species with [M(CO)3(NCCH3)]+, where M = Mn or Re, yields [PPN][MRu3(CO)1223-NC(μ-O)CH3]. The high nucleophilicity of the oxo ligand in [Ru3(CO)93-O)]2− (I) appears to be responsible for the conversion of acetonitrile to an acetamidediato ligand and for the instability of I. The crystal structure of [PPN][MnRu3(CO)1223-NC(μ-O)CH3)]] reveals a hinged butterfly array of metal atoms in which the acetamidediato ligand bridges the two wings with μ3-N bonding to an Mn and two Ru atoms, and μ-O bonding to an Ru atom.  相似文献   

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