首页 | 本学科首页   官方微博 | 高级检索  
相似文献
 共查询到20条相似文献,搜索用时 31 毫秒
1.
Kragten J  Decnop-Weever LG 《Talanta》1980,27(12):1047-1050
From the precipitation borderline in the pM′—pH diagram, determined experimentally under CO2-free conditions, the stability constants of the mononuclear and polynuclear species of gadolinium hydroxide have been established. The values found are log*β1 = −7.3, log*β2 = −14.6, log*β3 = −21.9, log*β4,3 = −19.0 and log *Ks0 = 17.0. They refer to fresh precipitates, prepared at room temperature in sodium perchlorate medium with an ionic strength of 1.  相似文献   

2.
Reactions of [(η6-arene)RuCl2]2 (1) (η6-arene=p-cymene (1a), 1,3,5-Me3C6H3 (1b), 1,2,3-Me3C6H3 (1c) 1,2,3,4-Me4C6H2(1d), 1,2,3,5-Me4C6H2 (1e) and C6Me6 (1f)) or [Cp*MCl2]2 (M=Rh (2), Ir (3); Cp*=C5Me5) with 4-isocyanoazobenzene (RNC) and 4,4′-diisocyanoazobenzene (CN–R–NC) gave mononuclear and dinuclear complexes, [(η6-arene)Ru(CNC6H4N=NC6H5)Cl2] (4a–f), [Cp*M(CNC6H4N=NC6H5)Cl2] (5: M=Rh; 6: M=Ir), [{(η6-arene)RuCl2}2{μ-CNC6H4N=NC6H4NC}] (8a–f) and [(Cp*MCl2)2(μ-CNC6H4N=NC6H4NC)}] (9: M=Rh; 10: M=Ir), respectively. It was confirmed by X-ray analyses of 4a and 5 that these complexes have trans-forms for the ---N=N--- moieties. Reaction of [Cp*Rh(dppf)(MeCN)](PF6)2 (dppf=1,1′-bis (diphenylphosphino)ferrocene) with 4-isocyanoazobenzene gave [Cp*Rh(dppf)(CNC6H4N=NC6H5)](PF6)2 (7), confirmed by X-ray analysis. Complex 8b reacted with Ag(CF3SO3), giving a rectangular tetranuclear complex 11b, [{(η6-1,3,5-Me3C6H3)Ru(μ-Cl}4(μ-CNC6H4N=NC6H4NC)2](CF3SO3)4 bridged by four Cl atoms and two μ-diisocyanoazobenzene ligands. Photochemical reactions of the ruthenium complexes (4 and 8) led to the decomposition of the complexes, whereas those of 5, 7, 9 and 10 underwent a trans-to-cis isomerization. In the electrochemical reactions the reductive waves about −1.50 V for 4 and −1.44 V for 8 are due to the reduction of azo group, [---N=N---]→[---N=N---]2−. The irreversible oxidative waves at ca. 0.87 V for the 4 and at ca. 0.85 V for 8 came from the oxidation of Ru(II)→Ru(III).  相似文献   

3.
Equilibria between aluminium(III), pyrocatechol (1,2-dihydroxybenzene, H2L) and OH were studied in 0.6 M Na(Cl) medium at 25°C. The measurements were performed as emf titrations (glass electrode) within the limits 1.5 ≤ − log[H+] ≤ 9; 0.0005 ≤ B ≤ 0.015 M; 0.006 ≤ C ≤ 0.03 M and 2 ≤ C/B ≤ 30 (B and C stand for the total concentrations of aluminium(III) and pyrocatechol respectively). All data can be explained with a main series of complexes: A1L+, log β−2,1,1 = − 6.337 ± 0.005; A1L2, log β−4,1,2 = −15.44 ± 0.017 and A1L33−, log β−6,1,3 = − 28.62 ± 0.024 together with two minor species: Al(OH)L22−, log β−5,1,2 = − 23.45 ± 0.079 and Al3(OH)3L3, log β−9,3,3 = − 29.91 ± 0.066. Of the two, the latter probably is a type of average composition complex principally occurring at low C/B quotients. The first acidity constant for pyrocatechol as determined in separate experiments is log β−1,0,1 = − 9.198 ± 0.001. The standard deviations given are 3σ(log β p,q,r). Data were analyzed with the least squares computer program LETAGROPVRID. In a model calculation using kaolinite as solid phase, we compared the complexation ability of this system with that of the system Al3+-OH-salicylic acid, reported earlier in this series.  相似文献   

4.
The Arrhenius equation corresponding to the process P---Ag+P*---Ag*→---P---Ag*+P*---Ag has been determined for [(η6-p-cymene)Ru(μ-pz)3Ag(PPh3)] (1) by complete line-shape analysis of the 31P NMR spectra between −40°C and +30°C. It has the form K = 1011.8± e(−46±5 kJ mol−1/RT). The preexponential term, log A = 11.8 corresponds to a small activation entropy, whereas the activation energy, 46 kJ mol−1 is comparable to those determined for other phosphorus—metal compounds.  相似文献   

5.
Medium-resolution spectra of the N2 b1Πu-X1Σg+ band system were recorded by 1 + 1 multiphoton ionization. In the spectra we found different linewidths for transitions to different vibrational levels in the b 1Πu state: Δν0 = 0.50 ± 0.05 cm−1, Δν1 = 0.28 ± 0.02 cm−1, Δν2 = 0.65 ± 0.06 cm−1, Δν3 = 3.2 ± 0.5 cm−1, Δν4 = 0.60 ± 0.07 cm−1, and Δν5 = 0.28 ± 0.02 cm−1. From these linewidths, predissociation lifetimes τν were obtained: τ0 = 16 ± 3 ps, τ1 > 150 ps, τ2 = 10 ± 2 ps, τ3 = 1.6 ± 0.3 ps, τ4 = 9 ± 2 ps, and τ5 > 150 ps. Band origins and rotational constants for the b 1Πuν = 0 and 1 levels were determined for the 14N2 and 14N15N molecules.  相似文献   

6.
Carnosine (β-alanyl-L-histidine) is a biologically active molecule involved in muscular metabolism. It crystallises in the C; space group with a = 24.725 Å b = 5,427 Å c = 8,004 Å β = 100,2° (Z = 4)

In the crystal, acid and basic groups are engaged in hydrogen bonds whose strength is evaluated through IR frequencies. Molecular conformation in the solid state is defined by τ1 = /t-177° τ2 = −38° φ = −96° ψ = +131° χ1 = 181° χ21 = 62°

NMR study of carnosine in aqueous solution indicates that rotation about CH2-CH2 is free and that the other angles take the following values: Ø −150° or −90° and X1 = 165° or 315°. Infrared and Raman spectra suggest that τ2 undergoes small changes when going from crystal to solution while ψ is close to +150°.  相似文献   


7.
Irradiation of Cp2* Nb(η2---S2)H (Cp* = C5Me5) 1a in the presence of Fe(CO)5 gives the CO-free complex [Cp2*NbS2]2Fe 2a. The core of 2a contains an FeS4 tetrahedron which is ligated by two niobocene ligands as shown by X-ray diffraction analysis. In the reaction of 1a or Cp2xNb(η2---S2)H (CPx = C5Me4Et) 1b with Co2(CO)8, compounds 3a and 3b of the same type are formed. Electrochemical studies of 2a and 3a,b show that they undergo three reversible 1e steps. The oxidation of 3b exerts a considerable influence on its absorption spectrum. A qualitative EHMO analysis is in agreement with a strong delocalisation of electron density over the whole NbS2MS2Nb system.  相似文献   

8.
139La-NMR chemical shifts were measured for several anionic complexes of formulae Li(C4H8O2)3/2 [La(ν3-C3H5)4], [Li(C4H8O2)2][Cp′nLa(ν3-C3]H5)4−n] (Cp′ = Cp(ν5-C5H5); n = 1, 2 and Cp′ = Cp * (ν5-C5Me5); N = 1) and Li[RnLa(ν3-C3H4)4n] (R = N(SiMe3)2; n = 1, 2 and R = CCsIMe3; n = 4), as well as for neutral compounds for formulae La(ν3-C3H5)3Ln (L = (C4H8O2)1.5, (HMPT)2, TMED), Cp′nLa(ν3-C3H5)3−n (Cp′= Cp(ν5-Cp5H5), Cp *(ν5-C5Me5); n = 1, 2) and La(ν3-C3H2)2X(THF)2 X = Cl, Br, I). Typical ranges of the 139La-NMR chemical shifts were found for the different types of complex independent of number and kind of organyl groups directly bonded to lanthanum.

Zusammenfassung

139La-NMR-Spektroskopie wurde an einer Reihe anionischer Allyllanthanat(III)-Komplexe der Zusammensetzung ]- [La)ν3-C3H5)4, [Li(C4H8)2][Cp′nLa(ν3-C3H5)4−n(Cp′ = Cp(ν5-C5H5); n = 1, 2 und Cp′ = Cp * (ν5-C5Me5); N = 1) und Li[RnLa(ν3-C3H5)4−n (R = B(SiMe3)2; n = 1, 2 und R = CCSiMe3; n = 4 sowie neutraler Allyllanthan(III)-Komplexe der Zusammensetzung La(ν3-C3H5)3Ln (Ln = (C4H8O2)1.5, (HMPT)2, TMED), Cp′n, La(ν3-C3H5)3−n (Cp′ = Cp(ν5-C5H5), Cp * (ν5- Cp5Me5); n = 1, 2) und La(ν3-Cp3H5)2X(THF)2 (X = Cl, Br, I) durchgefürt. In Abhängikeit von der Anzahl und der Art der am Lanthan gebundenen Gruppen wurden für die verschieden Komplextypen charakteristische Resonanzbereiche ermittelt.  相似文献   


9.
The reaction of {HB(Me2pz)3}Mo(NCS)(S4) [HB(Me2pz)3 = hydrotris(3,5-dimethylpyrazolyl)borate anion] with dicarbomethoxyacetylene in refluxing toluene results in the formation of the brown, diamagnetic complex {HB(Me2pz)3}Mo(NCS){S2C2(CO2Me)2} (1) (the reactants above also yield 1 upon prolonged reaction in dichloromethane at 25°C), which has been characterized by X-ray crystallography. The mononuclear pseudo-octahedral complex contains a facially tridentate HB(Me2pz)3 ligand, a monodentate N-bound NCS ligand, and a bidentate S2C2(CO2Me)22− ligand having a near planar MoS2C4 fragment and a SC=CS bond distance of 1.342(15) Å. Solutions of 1 are unstable in air and decompose to produce {HB(Me2pz)3}MoO2(NCS) and {HB(Me2pz)3}MoO(NCS)2.  相似文献   

10.
The reaction of K[H6ReL2] with [RuHCl(CO)(PPh3)3−x {P(OPri}3)x](L2 = (PMePh2)2, dppe, (AsPh3)2, or (PPh3)2; x = 0, 1 or 2) leads to [L2(CO)HRe(μ-H)3RuH(PPh3)2−y{P(OPri)3}y] (x = 0 or 1, Y = 0; X = 2, Y = 1(L2 = PPh3)) in a first step. Under the reaction conditions most of these complexes react rapidly with the liberated phosphine giving [L2(CO)Re(μ-H)3Ru(PPh3)3−y- {P(OPri)3}y] (L2 = (PMePh2)2 or dppe, Y = 0; L2 = (PPh3)2, Y = 1) as the only iso complexes. The structure of [(PMePh2)2(CO)Re(μ-H)3Ru(PPh3)3] has been establishedby X-ray structure analysis. The complex [(PPh3)2(CO)Re(μ-H)3Ru(PPh3)2(P(OPri)3)] reacts with molecular hydrogen under pressure to generate [L2(CO)HRe(μ-H)3RuH(PPh3)(P(OPri)3) as the sole product.  相似文献   

11.
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   

12.
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   

13.
Binuclear complexes [{Cu(NN)(PhNHpy)}2(μ-OH)2](PF6)2, where NN=2,2′-bipyridine (bipy) or 1,10-phenanthroline (phen), have been synthesized and characterized by chemical analysis, conductance measurements and IR and electronic spectroscopy. The X-ray crystal structure of [{Cu(bipy)(PhNHpy)}2(μ-OH)2](PF6)2 shows a distorted square-planar pyramidal coordination for Cu(II), defined by two nitrogen atoms of bipy, two bridging oxygen atoms and the pyridinic nitrogen atom of the ligand. Magnetic susceptibility measurements (in the 4.8–290 K range) reveal coupling which is antiferromagnetic for the bipy complex (2J=−24.2 cm−1) and slightly ferromagnetic for the phen complex (2J=3.3 cm−1). The EPR spectra show the expected triplet signals.  相似文献   

14.
The spectrum of CD2HF was measured by high-resolution interferometric Fourier-transform IR (FTIR) spectroscopy (apodised instrumental band with:0.004 cm−1 fwhm) between 800 and 1200 cm−1 covering the four lowest fundamentals. A complete rotational analysis using a semi-automatic assignment procedure yields accurate band centres (ν9: 912.2028 cm−1, ν6:964.4994 cm−1, ν5: 1050.5104 cm−1, ν4: 1093.8632 cm−1) and a complete set of first-order Coriolis coupling constants. The most important couplings occur between ν9 and ν6a= 1.069 cm−1, ξc= −0.3535 cm−1) and between ν5 and ν4b= −0.80606 cm−1). The analysis was guided by and compared with results from our ab initio calculations for Coriolis constants and transition moments using CADPAC at TZP/MP2 level.  相似文献   

15.
The magnetic susceptibility of 1,1′,2,2′-tetramethylcobaltocene, Co[C5H3(CH3)2]2, and 1,1′-diethylcobaltocene, Co(C5H4C2H5)2, has been studied between 0.99 and 296 K. The data are well reproduced by a calculation of the dynamic Jahn-Teller effect for the 2E1g(a1g2e2g4e1g) ground state of D5d symmetry. A suitable set of parameter values is given by ζ = 100 cm−1, δ = 150 cm−1, kJT = 0.40, κ = 0.70. The magnetism of cobaltocene, Co(C5H5)2, may be described by parameter values of comparable magnitude. The results imply a significantly larger reduction of the spin-orbit coupling parameter ζ due to covalency than of the orbital reduction factor κ.  相似文献   

16.
The convergence of ab initio calculations of the beryllium dimer potential is examined with several basis sets orders of perturbation theory. When the atomic pair natural orbital basis set calculations are extrapolated to the complete basis set and full CI limits, the calculated parameters: Re=2.447 Å, De=827 cm−1, ν01=212.7 cm−1, ν12=167.2 cm−1, ν23=121.5 cm−1 and ν34=77.7 cm−1 are in good agreement with the experimental parameters: Re=2.45 Å, De=839±10 cm−1, ν01=223.2 cm−1, ν12=169.7 cm−1, ν23=122.5 cm−1, and ν34=79 cm−1.  相似文献   

17.
Reaction of [Pt25-C5Me5)2(η-Br)3]3+(Br)3 with C5R5H (R = H,Me) in the presence of AgBF4 gives the first platinocenium dications, [Pt(η5-C5Me5)(η5-C5R5)]2+(BF4 )2. On electrochemical reduction, [pt(η5-C5Me5)2]2+ yields [Pt(η4-C5Me5H)(η2-C5Me5)]+ BF4. kw]Cyclopentadienyl; Metallocenes; Platinum; Electrochemistry  相似文献   

18.
The new diphenolato complexes [{Mo(NO){HB(dmpz)3}Cl}2Q] where dmpz = 3,5-dimethylpyrazolyl and Q = OC6H4(C6H4O (n = 1 or 2), OC6H4CR=CRC6H4O (R = H or Et), and OC6H4CH=CHC6H4CH=CHC6H4O have been prepared and their electrochemical properties (cyclic and differential pulse voltammetry) compared with previously reported analogues where Q = OC6H4O, OC6H4EC6H4O (E = SO2, CO and S), OC6H4 (CO)C6H4 C6H4(CO)C6H4O and 1,5- and 2,7-O2C10H6. The electrochemical interaction between the redox centres in the new complexes is very weak, in contrast to that in the 1,4-benzenediolato and naphthalendiolato species. The EPR spectra of the reduced mixed-valence species [{Mo(NO){HB(dmpz)3}Cl}2Q] where Q = 1,3- and 1,4-OC6H4O and OC6H4SC6H4O shows that they are valence-trapped at room temperature, whereas those of the dianions [{Mo(NO){HB(dmpz)3}Cl}2Q]2− where Q = 1,4-OC6H4O, OC6H4EC6H4O (E = CO or S) and OC6H4CH=CHC6H4CH=CHC6H4O shows that the unpaired spins on each molybdenum centre are strongly correlated (J, the spin exchange integral AMo, the metal-hyperfine coupling constant). The electrochemical properties and the comproportionation constants for the reaction [{Mo(NO){HB(dmpz)3} Cl}2Q] + [{Mo(NO){HB(dmpz)3}Cl}O]2]2−2[{Mo(NO) {HB(dmpz)3}Cl}2Q] where Q = diphenolato bridge, are compared with related compounds containing benzenediamido and dianilido bridges.  相似文献   

19.
Nest-shaped cluster [MoOICu3S3(2,2′-bipy)2] (1) was synthesized by the treatment of (NH4)2MoS4, CuI, (n-Bu)4NI, and 2,2′-bipyridine (2,2′-bipy) through a solid-state reaction. It crystallizes in monoclinic space group P21/n, a=9.591(2) Å, b=14.820(3) Å, c=17.951(4) Å, β=91.98(2)°, V=2549.9(10) Å3, and Z=4. The nest-shaped cluster was obtained for the first time with a neutral skeleton containing 2,2′-bipy ligand. The non-linear optical (NLO) property of [MoOICu3S3(2,2′-bipy)2] in DMF solution was measured by using a Z-scan technique with 15 ns and 532 nm laser pulses. The cluster has large third-order NLO absorption and the third-order NLO refraction, its 2 and n2 values were calculated as 6.2×10−10 and −3.8×10−17 m2 W−1 in a 3.7×10−4 M DMF solution.  相似文献   

20.
Organolanthanide chloride complexes [(CH3OCH2CH2C5H4)2Ln(μ-Cl)]2 (Ln = La, Pr, Ho and Y) react with excess NaH in THF at 45°C to give the dimeric hydride complexes [(CH3OCH2CH2C5H4)2Ln(μ-H)]2, which have been characterized by IR, 1H NMR, MS and XPS spectroscopy, elemental analyses and X-ray crystallography. [(CH3OCH2CH2C5H4)2Y(μ-H)]2 crystallizes from THF/n-hexane at −30°C, in the triclinic space group P1 with a = 8.795(2) Å, b = 11.040(1) Å, c = 16.602(2) Å, = 93.73(1)°, β = 91.82(1)°, γ = 94.21(1)°, Dc = 1.393 gcm−3 for Z = 2 dimers. However, crystals of [(CH3OCH2CH2C5H4)2Ho(μ-OH)]2 were obtained by recrystallization of holmium hydride in THF/n-hexane at −30°C, in the orthorhombic space group Pbca with a = 11.217(2) Å, b = 15.865(7) Å, c = 17.608(4) Å, Dc = 1.816 gcm−3 for Z = 4 dimers. In the complexes of yttrium and holmium, each Ln atom of the dimers is coordinated by two substituted cyclopentadienyl ligands, one oxygen atom and two hydrogen atoms (for the Y atom) or two hydroxyl groups (for the Ho atom) to form a distorted trigonal bipyramid if the C(η5)-bonded cyclopentadienyl is regarded as occupying a single polyhedral vertex.  相似文献   

设为首页 | 免责声明 | 关于勤云 | 加入收藏

Copyright©北京勤云科技发展有限公司  京ICP备09084417号