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1.
Bicomycin A1 oligonucleotide derivative was used for direct cleavage of a DNA target. In the presence of Fe2+ ions and 2-mercaptoethanol, Blm-R-pd(CCAAACA) (I) damaged the target, pd(TGTTTGGCGAAGGA), with the yield of 80%, without affecting its own oligonucleotide tail. The sites of the cleavage were T?-T? and G?-G?. Unbound bleomycin A5, damaged the G6-G7-G8 site. Reagent I formed more stable complementary complexes with the target than parent oligonucleotide (ΔTm=11°C)  相似文献   

2.
《FEBS letters》1994,350(2-3):195-198
The H+-ATPase from chloroplasts, CF0F1, was isolated, purified and reconstituted into asolectin liposomes. The enzyme was brought either into the oxidized state or into the reduced state, and the rate of ATP synthesis was measured after energisation of the proteoliposomes with an acid—base transition ΔpH (pHin = 5.0, pHout = 8.5) and a K+/valinomycin diffusion potential, Δφ (K+in = 0.6 mM, K+out = 60 mM). A rate of 250 s−1 was observed with the reduced enzyme (85 s−1 in the absence of Δφ). A rate of 50 s−1 was observed with the oxidized enzyme under the same conditions (15 s−1 in the absence of Δφ). The reconstituted enzyme contained 2 ATPbound per CF0F1 and 1 ADPbound per CF0F1. Upon energisation the enzyme was activated and 0.9 ADP per CF0F1, was released. Binding of ADP to the active reduced enzyme was observed under different conditions. In the absence of phosphate the rate constant for ADP binding was 105 M−1·s−1 under energized and de-energized conditions. In the presence of phosphate the rate of ADP binding drastically increased under energized conditions, and strongly decreased under de-energized conditions.  相似文献   

3.
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   

4.
Similar rates have been observed for dimer repair with Escherichia coli photolyase and the heterogeneous mixtures generated by UV irradiation of oligothymidylates [UV-oligo(dT)n, n greater than or equal to 4] or DNA. Comparable stability was observed for ES complexes formed with UV-oligo(dT)n, (n greater than or equal to 9) or dimer-containing DNA. In this paper, binding studies with E. coli photolyase and a series of homogeneous oligonucleotide substrates (TpT, TpTp, pTpT, TpTpT, TpTpT, TpTpTpT, TpTpTpT, TpTpTpT, TpTpTpT) show that about 80% of the binding energy observed with DNA as substrate (delta G approximately 10 kcal/mol) can be attributed to the interaction of the enzyme with a dimer-containing region that spans only four nucleotides in length. This major binding determinant (TpTpTpT) coincides with the major conformational impact region of the dimer and reflects contributions from the dimer itself (TpT, delta G = 4.6 kcal/mol), adjacent phosphates (5'p, 0.8 kcal/mol; 3'p, 1.1 kcal/mol), and adjacent thymine residues (5'T, 0.8 kcal/mol; 3'T, 1.3 kcal/mol). Similar turnover rates (average kcat = 6.7 min-1) are observed with short-chain oligonucleotide substrates and UV-oligo(dT)18, despite a 25,000-fold variation in binding constants (Kd). In contrast, the ratio Km/Kd decreases as binding affinity decreases and appears to plateau at a value near 1. Turnover with oligonucleotide substrates occurs at a rate similar to that estimated for the photochemical step (5.1 min-1), suggesting that this step is rate determining. Under these conditions, Km will approach Kd when the rate of ES complex dissociation exceeds kcat.(ABSTRACT TRUNCATED AT 250 WORDS)  相似文献   

5.
The fluorescence induction and other fluorescence properties of spinach chloroplasts at room temperature were probed utilizing two 30-ps wide laser pulses (530 nm) spaced Δt (s) apart in time (Δt = 5–110 ns). The energy of the first pulse (P1) was varied (1012–1016 photons · cm−2), while the energy of the second (probe) pulse (P2) was held constant (5 · 1013 photons · cm−2). A gated (10 ns) optical multichannel analyzer-spectrograph system allowed for the detection of the fluorescence generated either by P1 alone, or by P2 alone (preceded by P1). The dominant effect observed for the fluorescence yield generated by P1 alone is the usual singlet-singlet exciton annihilation which gives rise to a decrease in the yield at high energies. However, when the fluorescence yield of dark-adapted chloroplasts is measured utilizing P2 (preceded by pulse P1) an increase in this yield is observed. The magnitude of this increase depends on Δt, and is characterized by a time constant of 28 ± 4 ns. This rise in the fluorescence yield is attributed to a reduction of the oxidized (by P1) reaction center P-680+ by a primary donor. At high pulse energies (P1 = 4 · 1014 photons · cm−2) the magnitude of this fluorescence induction is diminished by another quenching effect which is attributed to triplet excited states generated by intense P1 pulses. Assuming that the P1 pulse energy dependence of the fluorescence yield rise reflects the closing of the reaction centers, it is estimated that about 3–4 photon hits per reaction center are required to close completely the reaction centers, and that there are 185–210 chlorophyll molecules per Photosystem II reaction center.  相似文献   

6.
《FEBS letters》1988,230(1-2):109-115
We investigated the binding of subunit δ to solubilized chloroplast ATPase. Purified δ was covalently labeled with eosin 5-isothiocyanate and its rotational correlation time was determined by a photoselection technique as a function of added CF1 (containing δ) and of CF1(−δ) (lacking δ). In aqueous buffer the rotational correlation time of labeled δ was 33 ns. This is compatible with a rather elongated shape with the dimensions 2b = 100 Å/2a = 28 Å. Binding of δ to CF1 decreased the rotational correlation time about 10-fold. The result was a biphasic decay of the laser flash-induced absorption anisotropy which was analyzed to yield the proportion of δ (bound to CF1) relative to δ (free). CF1(−δ), which completely lacked the δ-subunit, bound one δ (mol/mol) with high affinity (Kd ≈ 100 nM) and at least another δ with about 20-fold lower affinity. The δ-containing CF1, revealed only the low-affinity site(s) for δ. This was compatible with a 1:1 stoichiometry of δ in isolated CF1.  相似文献   

7.
The chloro complexes trans-[Pt(Me)(Cl)(PPh3)2], after treatment with AgBF4, react with 1-alkynes HC---C---R in the presence of NEt3 to afford the corresponding acetylide derivatives trans-[Pt(Me) (C---C---R) (PPh3)2] (R = p-tolyl (1), Ph (2), C(CH3)3 (3)). These complexes, with the exception of the t-butylacetylide complex, react with the chloroalcohols HO(CH2)nCl (n = 2, 3) in the presence of 1 equiv. of HBF4 to afford the alkyl(chloroalkoxy)carbene complexes trans-[Pt(Me) {C[O(CH2)nCl](CH2R) } (PPh3)2][BF4] (R = p-tolyl, N = 2 (4), N = 3 (5); R=Ph, N = 2 (6)). A similar reaction of the bis(acetylide) complex trans-[Pt(C---C---Ph)2(PMe2Ph)2] with 2 equiv. HBF4 and 3-chloro-1-propanol affords trans-[Pt(C---CPh) {C(OCH2CH2CH2Cl)(CH2Ph) } (PMe2Ph)2][BF4] (7). T alkyl(chloroalkoxy)-carbene complex trans-[Pt(Me) {C(OCH2CH2Cl)(CH2Ph) } (PPh3)2][BF4] (8) is formed by reaction of trans-[Pt(Me)(Cl)(PPh3)2], after treatment with AgBF4 in HOCH2CH2Cl, with phenylacetylene in the presence of 1 equiv. of n-BuLi. The reaction of the dimer [Pt(Cl)(μ-Cl)(PMe2Ph)]2 with p-tolylacetylene and 3-chloro-1-propanol yields cis-[PtCl2{C(OCH2CH2CH2Cl)(CH2C6H4-p-Me}(PMe2Ph)] (9). The X-ray molecular structure of (8) has been determined. It crystallizes in the orthorhombic system, space group Pna21, with a = 11.785(2), B = 29.418(4), C = 15.409(3) Å, V = 4889(1) Å3 and Z = 4. The carbene ligand is perpendicular to the Pt(II) coordination plane; the PtC(carbene) bond distance is 2.01(1) Å and the short C(carbene)-O bond distance of 1.30(1) Å suggests extensive electronic delocalization within the Pt---C(carbene)---O moietry.  相似文献   

8.
R. LEMA-KISOKA, N. HAYEZ, I. LANGER, P. ROBBERECHT, E. SARIBAN AND C. DELPORTE. Characterization of functional VIP/PACAP receptors in the human erythroleukemic HEL cell line. PEPTIDES. The presence of VIP/PACAP receptors was investigated on the human erythroleukemic cell line HEL. Specific binding of [125I]-PACAP or [125I]-VIP on HEL cells or membranes was very low and did not allow to perform competition curves. At 37°C PACAP transiently increased cAMP levels in the presence of the non-specific phosphodiesterase inhibitor IBMX, suggesting rapid desensitization. Kinetic studies revealed that optimal conditions to measure the EC50 of PACAP(1–27) were 10 min at 20°C. Under those conditions, PACAP-related peptides increased cAMP levels with EC50 in agreement with the pharmacological profile of the VPAC1 receptor subtype: PACAP = VIP > [K15, R16, L27]VIP(1–7)/GRF(8–27) = [R16]ChSn (two VPAC1 agonists) HELODERMIN = secretin. RO 25–1553, a selective activator of VPAC2 receptor was inactive at 1 μM. Dose-response curves of VPAC1 agonist molecules (PACAP, VIP, [K15, R16, L27]VIP(1–7)/GRF(8–27), [R16]ChSn) were shifted to the right by the VPAC1 receptor antagonist [AcHis1, D-Phe2, Lys15, Leu17]VIP(3–7)/GRF(8–27), with a Ki of 3 ± 1 nM (n = 3). The presence of VPAC1 receptor mRNA was confirmed by RT-PCR. Preincubation with PACAP or PMA showed that VPAC1 receptors underwent homologous and heterologous desensitization.

This study provides the first evidence for the expression of functional VPAC1 receptors undergoing rapid desensitization in HEL cells.  相似文献   


9.
The reaction of perrhenate with 2-hydrazinopyrimidine in MeOH–HCl yields [ReCl31-NNC4H3N2H)(η2-HNNC4H3N2)] (1). The analogous reaction with Na2MoO4 yields [MoCl31-NNC4H3N2H)(η2-HNNHC4H3N2)] (1a). The reaction of 1 with pyrimidine-2-thiol and triethylamine produces [Re(η1-C4H3N2S)(η2-C4H3N2S)(η1-NNC4H3N2)(η2-HNNC4H3N2)] (2), while reaction of 1 with the Schiff base HSC6H4N=C(H)C6H4OH provides [Re(η3-SC6H4N=C(H)C6H4O)(η1-NNC4H3N2)(η2-HNNC4H3N2)]·0.6CH2Cl2 (3·0.6CH2Cl2). The analogous hydrazinopyridine complex of the Schiff base, [Re(η3-SC6H4N=C(H)C6H4O)(η1-NNC5H4N)(η2-HNNC5H4N)] (4), was also synthesized by reacting [ReCl31-NNC5H4NH)(η2-HNNC5H4N)] with HSC6H4N=C(H)C6H4OH. The crystal structures of 1–4 have been determined.  相似文献   

10.
Complexes of type A4[VO(tart)]2·nH2O, where A = Rb or Cs and tart =d,l-tartrate(4−) (n = 2) or d,d-tartrate(4−) (n = 2 for Rb and n = 3 for Cs), were prepared from an aqueous mixture of V2O5, AOH and H4tart. These complexes were studied by single-crystal X-ray diffraction methods: Rb4[VO(d,l-tart)]2·2H2O, space group P1 with a = 8.156(1),b = 8.246(1),c = 8.719(1)Å, = 66.09(1)°, β = 65.07(1)°, γ = 82.40(1)°,Z = 2, 1917 observed reflections, and final Rw = 0.035; Cs4[VO(d,l-tart)]2·2H2O, space group P21/c with a = 9.350(1),b = 13.728(2),c = 8.479(1)Å, β = 106.77(1)°,Z = 4, 2235 observed reflections, and final Rw = 0.054; Rb4[VO(d,d-tart)]2·2H2O, space group P4122 with a = 8.072(1),c = 32.006(3)Å,Z = 8, 1014 observed reflections and final Rw = 0.038; Cs4[VO(d,d-tart)]2·3H2O, space group P122 with a = 8.184(1),c = 33.680(5)Å,Z = 8, 1310 observed reflections, and final Rw = 0.063. Bulk magnetic susceptibility data (1.5–300 K) for these compounds and A4[VOl,l-tart)]2·nH2O (A = Rb, Cs) were obtained on polycrystalline samples. These data were analyzed in terms of a Van Vleck exchange coupled S = 1/2 model which was modified to include an interdimer exchange parameters Θ. Analysis of the low-temperature (1.5–20 K) susceptibility data gave 2J = +1.30 cm−1 and Θ = −1.86 K for Rb4[VO(d,l-tart)]2·2H2O, 2J = +1.16 cm−1 and Θ = −1.69 K for Cs4[VO(d,l-tart)]2·2H2O, 2J = +1.90 cm−1 and Θ = −0.82 K for Rb4[VO(d,d-tart)]2·2H2O, 2J = +2.04 cm−1 and Θ = −0.80 K for Rb4[VO(l,l-tart)]2·2H2O, 2J = +1.52 cm−1 and Θ = −0.25 K for Cs4[VO(d,d-tart)]2·3H2O, and 2J = +1.64 cm−1 and Θ = −0.31 K for Cs4[VO(l,l-tart)]2·3H2O. These results suggest the magnitudes of intradimer (ferromagnetic and interdimer (antiferromagnetic) exchange interactions are similar in these complexes, as observed for the analogous Na salts.  相似文献   

11.
The kinetics of substitution reactions of [η-CpFe(CO)3]PF6 with PPh3 in the presence of R-PyOs have been studied. For all the R-PyOs (R = 4-OMe, 4-Me, 3,4-(CH)4, 4-Ph, 3-Me, 2,3-(CH)4, 2,6-Me2, 2-Me), the reactions yeild the same product [η5-CpFe(CO)2PPh3]PF6, according to a second-order rate law that is first order in concentrations of [η5-CpFe(CO)3]PF6 and of R-PyO but zero order in PPh3 concentration. These results, along with the dependence of the reaction rate on the nature of R-PyO, are consistent with an associative mechanism. Activation parameters further support the bimmolecular nature of the reactions: ΔH = 13.4 ± 0.4 kcal mol−1, ΔS = −19.1 ± 1.3 cal k−1 mol−1 for 4-PhPyO; ΔH = 12.3 ± 0.3 kcal mol−1, ΔS = 24.7 ±1.0 cal K−1 mol−1 for 2-MePyO. For the various substituted pyridine N-oxides studied in this paper, the rates of reaction increase with the increasing electron-donating abilities of the substituents on the pyridine ring or N-oxide basicities, but decrease with increasing 17O chemical shifts of the N-oxides. Electronic and steric factors contributing to the reactivity of pyridine N-oxides have been quantitatively assessed.  相似文献   

12.
The reaction of dilithiated o-carborane (closo-1,2-Li2-1,2-C2B10H10) with CuCl2 gives 1,1′-bis(o-carborane) (1), 1,3′-bis(o-carborane) (2) and 1,4′-bis(o-carborane) (3). Compound 2 (C4B20H22) crystallizes in the monoclinic space group P21/n with A = 6.9275(6), B = 9.7655(8), C = 12.356(1) Å, β = 90.028(2)° and Z = 2. The structure was solved by direct methods and refined to R = 0.048 and Rw = 0.074. Compound 3 (C4B20H22) crystallizes in the orthorhombic space group P212121 with A = 6.8854(5), B = 12.523(1), C = 19.847(1) Å and Z = 4. The structure was solved by direct methods and refined to R = 0.078 and Rw = 0.091. The coupling reaction of dilithiated m-carborane (closo-1,7-Li2-1,7-C2B10H10) with CuCl2 results in the formation of 1,1′-bis(m-carborane) (4) and tetra(m-carborane) (5).  相似文献   

13.
Polyphosphates of different chain lengths (P3, P4, P15, P35), (1 μM) inhibited 10, 60, 90 and 100%, respectively, the primer (tRNA) dependent synthesis of poly(A) catalyzed poly(A) polymerase from Saccharomyces cerevisiae. The relative inhibition evoked by p4A and P4 (1 μM) was 40 and 60%, respectively, whereas 1 μM Ap4A was not inhibitory. P4 and P15 were assayed as inhibitors of the enzyme in the presence of (a) saturating tRNA and variable concentrations of ATP and (b) saturating ATP and variable concentrations of tRNA. In (a), P4 and P15 behaved as competitive inhibitors, with Ki values of 0.5 μM and 0.2 μM, respectively. In addition, P4 (at 1 μM) and P15 (at 0.3 μM) changed the Hill coefficient (nH) from 1 (control) to about 1.3 and 1.6, respectively. In (b), the inhibition by P4 and P15 decreased V and modified only slightly the Km values of the enzyme towards tRNA.  相似文献   

14.
Methanobacterium thermoautotrophicum, strain Hveragerdi, has been cultivated in a completely defined mineral salts medium, under strictly anaerobic conditions with CO2 and H2 as sole carbon and energy source, respectively. During optimization of the medium an iron limitation was identified that could not be overcome by the simple addition of iron—or iron complexed with nitrilotriacetate (NTA)—to the medium, due to the formation of insoluble FeS complexes. In order to define a medium optimization strategy, and to avoid laborious empirical optimization procedures, a theoretical model has been developed in order to describe the solubility of iron and other mineral species in the medium as a function of the concentration of sulfur and NTA. This model may be applied for the optimization of any medium component. With this information sulfide has been replaced by a combination of cysteine and thiosulphate in conjunction with a non-toxic reducing agent (titanium (III) citrate). Using this defined medium precipitation was avoided and an iron limitation was overcome resulting in a 5-fold improvement of the final biomass concentration from 2–3 g l−1 to 11.2 g l−1 together with a 2-fold increase (from 45 to almost 100%) in the conversion of CO2 and H2 to CH4, even at gas flow rates as high as 6 l min−1.  相似文献   

15.

1. 1.|Fourteen male volunteers were examined under passive heating.

2. 2.|Electrical skin resistance (ESR) and rectal temperature (Tre) were measured during the whole period of exposure.

3. 3.|It was found that:

• —|ESR decreases rapidly with increasing air temperature. Assuming an exponential curve yields a mean time constant of 14 min.

• —|There is a correlation between the individual ESR time constants and Tre increases (r = 0.695, P < 0.005).

• —|Additional changes of ESR were noted in 8 subjects at a constant air temperature of 42°C.

4. 4.|It is concluded that ESR may be a useful indicator of the sweating response of the human thermoregulatory system during exogenous heat load.

Author Keywords: Electrical skin resistance; rectal temperature; sweating; heating, man  相似文献   


16.
Reaction of (NEt4)2MS4 (M = Mo, W) with CuCl and KSCN (or NH4SCN) in acetone or acetonitrile affords a new set of mixed metal–sulfur compounds: infinite anionic chains Cu4(NCS)5MS43− (1,2), (CuNCS)3WS42− (3) and two dimensional polymeric dianions (CuNCS)4MS42− (4,5). Crystal of 1 (M = W) and 3 are triclinic, space group P1(1:a = 10.356(2),b = 15.039(1),c = 17.356(2)Å, = 78.27(1)°, β = 88.89(2)° and γ = 88.60(1)°,Z = 2,R = 0.04 for 3915 independent data;3:a = 8.449(2),b = 14.622(4),c = 15.809(8)Å, = 61.84(3)°, β = 73.67(3)° and γ = 78.23(2)°,Z = 2,R = 0.029 for 6585 independent data). Crystals of 4 (M = W) and 5 (M = Mo) are monoclinic, space group P21/m,Z = 2 (4:a = 12.296(4),b = 14.794(4),c = 10.260(3)Åand β = 101.88(3)°,R = 0.034 for 4450 independent data;5:a = 12.306(2),b = 14.809(3),c = 10.257(2)Åand β = 101.99(3)°,R = 0.043 for 3078 independent data). The crystal structure determinations of 4 and 5 show that four edges of the tetrahedral MS42− core are coordinated by copper atoms forming WS4Cu4 aggregates linked by eight-membered Cu(NCS)2Cu rings. A two-dimensional network is thus formed in the diagonal (101) plane. The space between the anionic two-dimensional networks is filled with the NEt4+ cations. Additional NCS groups lead to the [Cu4(NCS)5WS4]3− (1) trianion connected by NCS bridges forming pseudo-dimers. These latter are held together by weak CuS(NCS) interactions giving rise to infinite chains along a direction parallel to [100]. In contrast complex3 develops infinite chains from WS4Cu3 aggregates with the same Cu(NCS)2Cu bridges as in 4 and 5. These chains are running along a direction parallel to [010]. The structural data of the different types of polymeric compounds containing MS42− and CuNCS have been used to interpret vibrational spectroscopic data of the thiocyanate groups.  相似文献   

17.
Complexes RuCl3(PPh3)L2 (L = MeIm (1a, Im (1b)) and [RuCl2(PPh3)2(bipy)]Cl·4H2O (2) have been synthesized via the ruthenium(III) precursor RuCl3(PPh3)2 (DMA), and characterized, including an X-ray structural analysis for 1a (MeIm = N-methylimidazole, Im = imidazole, bipy = 2,2′-bipyridyl, and DMA = N, N′-dimethylacetamide). Crystals of 1a are monoclinic, space group P21/n, A = 10.5491(5), B = 20.4934(9), C = 12.8285(4) Å, β = 90.166(4)°, Z = 4. The structure, which reveals a mer configuration for the chlorides, and cis-methylimidazoles, was solved by conventional heavy atom methods and was refined by full-matrix least-square procedures to R = 0.041 and Rw = 0.042 for 3328 reflections with I 3σ(I). From the RuCl2(PPh3)3 precursor, the ruthenium(II) complexes RuCl2(PPh3)2L2 and [RuCl(PPh3)L4]Cl have been made (L = Im or MeIm), while [RuCl(dppb)Im3]Cl has been made from [RuCl2(dppb)]2(μ-dppb) (dppb = Ph2P(CH2)4PPh2).  相似文献   

18.
Treatment of the A-ring aromatic steroids estrone 3-methyl ether and β-estradiol 3, 17-dimethyl ether with Mn(CO)5+BF4 in CH2Cl2 yields the corresponding [(steroid)Mn(CO)3]BF4 salts 1 and 2 as mixtures of and β isomers. The X-ray structure of [(estrone 3-methyl ether)Mn(CO)3]BF4 · CH2Cl2 (1) having the Mn(CO)3 moiety on the side of the steroid is reported: space group P21 with a=10.3958(9), b=10.9020(6), c=12.6848(9) Å, β=111.857(6)°, Z=2, V=1334.3(2) Å3, 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 NaBH4 and LiCH2C(O)CMe3 add to [(β-estradiol 3,17-dimethyl ether)Mn(CO)3]BF4 (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-CH2C(O)CMe3 substituent is reported (complex 4): space group P212121 with a=7.5154(8), b=15.160(2), c=25.230(3) Å, Z=4, V=2874.4(5) Å3, 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   

19.
The phosphinoalkenes Ph2P(CH2)nCH=CH2 (n= 1, 2, 3) and phosphinoalkynes Ph2P(CH2)n C≡CR (R = H, N = 2, 3; R = CH3, N = 1) have been prepared and reacted with the dirhodium complex (η−C5H5)2Rh2(μ−CO) (μ−η2−CF3C2CF3). Six new complexes of the type (ν−C5H5)2(Rh2(CO) (μ−η11−CF3C2CF3)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−CH3C5H4)Mn(CO)2thf resulted in coordination of the manganese to the alkene function. The Rh2---Mn complex [(η−C5H5)2Rh2(CO) (μ−η11−CF3C2CF3) {Ph2P(CH2)3CH=CH2} (η−CH3C5H4)Mn(CO)2] was fully characterized. Simi treatment of the dirhodium-phosphinoalkyne complexes with Co2(CO)8 resulted in the coordination of Co2(CO)6 to the alkyne function. The Rh2---Co2 complex [(η−C5H5)2Rh2(CO) (μ−η11−CF3C2CF3) {Ph2PCH2C≡CCH3}Co2(CO)2], C37H25Co2F6O7PRh2, 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 Rh2 and Co2 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 Rh2 and perpendicular for Co2. Attempts to induce Rh2Co2 cluster formation were unsuccessful.  相似文献   

20.
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   

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