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1.
The synthesis and characterization of [In(pbx)3] (1) (Hpbx = 2-(2′-hydroxylphenyl)benzoxazole) are presented. The ground and low lying excited electronic states in 1 are studied using density functional theory level (DFT). The optimized geometry is compared to the experimentally observed structure. Time-dependent density functional theory level (TDDFT) is employed to investigate the excited singlet states. The calculated energies of the low lying singlet states in 1 are in considerable agreement with the experimental data. All the low lying transitions are categorized as π → π∗ ligand-to-ligand charge transfer transitions (LLCT) in nature. The emissive state of 1 is assigned as a singlet metal-perturbed π → π∗ ligand-to-ligand charge transfer transition (LLCT). 相似文献
2.
Rhodium(III) complexes of 1,2-naphthoquinone-1-oxime (1-nqo) [Rh(1-nqo)L2Cl2] 1-3 [1, L = 4-methylpyridine (mpy); 2, L = 4-phenylpyridine (ppy); 3, L = 4-acetylpyridine (apy)] were prepared. The structure of complex 1 is analyzed by single crystal X-ray crystallography. All of the complexes were characterized by mass spectrometry, 1H-1H COSY NMR and FT-IR. UV-Vis absorption spectroscopy and cyclic voltammetry were employed to investigate the electronic transition behaviors of the complexes. The complexes displayed irreversible metal-localized two-electron reductions from RhIII to RhI on the cyclic voltammogram. While the low-energy absorptions at λmax of 488-490 nm on the UV-Vis spectra of the complexes were related to metal to 1-nqo ligand charge transfer [MLCT, dπ(Rh) → π∗(1-nqo)] and chloride to 1-nqo ligand charge transfer [LLCT, pπ(Cl) → π∗(1-nqo)] based on the theoretical calculations using time-dependent density functional theory (TD-DFT). 相似文献
3.
A mixed-ligand Cr(III) complex with 2-(2-hydroxyphenyl)benzimidazole, 1,10-phenanthroline and isophthalic acid, [Cr(pbm)2(phen)]X0.5 (1X0.5) (Hpbm = 2-(2-hydroxyphenyl)benzimidazole; phen = 1,10-phenanthroline; H2X = isophthalic acid) has been prepared by heating in aqueous solution and characterized, and the geometric structure and spectroscopic properties, investigated experimentally and theoretically by using the density functional theory level (DFT) and the time-dependent density functional theory level (TDDFT). The theoretical-experimental agreement is satisfactory. Further theoretical analyses of electronic structure and molecular orbitals have demonstrated that the low-lying absorption bands in UV-Vis spectrum are mainly π → π∗ ligand-to-ligand charge transfer transition (LLCT) and or π → (dz2-dx2-y2-dyz) ligand-to-metal charge transfer transition (LMCT) in nature. 相似文献
4.
Hong-Yan Li Jing Xiong Qiu-Lei Xu Yun-Mei Tao Jing-Lin Zuo 《Inorganica chimica acta》2011,370(1):398-3327
Six complexes (1-6) with the type of [Ru(bpy)2L]X2 (1-3: L = L1-L3, X = Cl−; 4-6: L = L1-L3, X = PF6−) were synthesized based on 2,2′-bipyridine and three 2,2′-bipyridine derivatives L1, L2 and L3 (L1 = 5,5′-dibromo-2,2′-bipyridine, L2 = 5-bromo-5′-carbazolyl-2,2′-bipyridine, L3 = 5,5′-dicarbazolyl-2,2′-bipyridine). The complexes 1-6 were characterized by 1H NMR, MS(ESI) and IR spectra, along with the X-ray crystal structure analysis for 1, 5 and 6. Their photophysical properties and electrochemiluminescence (ECL) properties were investigated in detail. In the UV-Vis absorption spectra, all complexes 1-6 show strong intraligand (π → π∗) transitions and metal-ligand charge transfer (MLCT, dπ (Ru) → π∗) bands. Upon the excitation wavelengths at ∼508 nm, all complexes 1-6 exhibit typical MLCT emission of ruthenium(II) polypyridyl complexes. The introduction of carbazole moieties improves the MLCT absorption and emission intensity. The ruthenium(II) complexes 1-6 exhibit good electrochemiluminescence (ECL) properties in [Ru(bpy)2L]2+/tri-n-propylamine (TPrA) acetonitrile solution and the complexes with PF6− showed higher ECL emission intensity than that of the complexes with Cl− based on the same ligands. 相似文献
5.
The synthesis, X-ray crystal structure and luminescence properties of a new bis-cyclometalated heteroleptic complex, [Ir(ppy)2(HDPA)](PF6) (1, ppy = 2-phenylpyridine, HDPA = 2,2′-dipyridylamine), are reported. Both at room temperature and 77 K, complex 1 exhibits intense blue emission, assigned as 3MLCT [dπ(Ir)-π∗(HDPA)] phosphorescence. Analysis of voltammetric data also provides evidence in support of this assignment. 相似文献
6.
Gabriele Heinze-Brückner 《Inorganica chimica acta》2011,374(1):385-391
A dinuclear ferric complex with the redox-active ligand (LCl2)2- (H2LCl2 = N,N′-dimethyl-bis(3,5-dichloro-2-hydroxybenzyl)-1,2-diaminoethane), was synthesized and characterized. The two iron(III) ions are six-coordinate in a distorted octahedral environment of the donor set of one (LCl2)2− and one amine and one phenolate donor of a second (LCl2)2−, which bridges the two complex halves. The relatively low-symmetric complex 1 crystallizes in the space group R. The crystal structure contains hexagonal, one-dimensional channels parallel to the c axis with diameters of ∼13 Å. The absorption spectrum of 1 exhibits strong characteristic features of pπ → dπ∗, pπ → dσ∗, phenolate-to-metal CTs, and π → π∗ ligand transitions. Electrochemical studies on 1 reveal the redox-activity of the coordinated ligand (LCl2)2− by showing irreversible oxidative electron-transfer waves. The reductive electron transfers at negative potentials seem to originate from metal-centered processes. A detailed comparison to complexes with similar donor sets provides new insights into the electrochemical properties of these kinds of complexes. 相似文献
7.
Sudipta Dalai Durga Sankar Chowdhuri Abhinandan Rana Ennio Zangrando 《Inorganica chimica acta》2010,363(14):3700-3705
Two coordination polymers of cadmium with formula [Cd(pyp)2(H2O)2]n (1) and {[Cd2(pyzca)3(atr)(H2O)]·H2O}n (2) [pypH = 3-pyridinepropionic acid, pyzcaH = 2-pyrazinecarboxylic acid and atrH = 5-aminotetrazole] have been synthesized and structurally characterized by X-ray single crystal diffraction analysis. Both complexes display 2D structures that extend into a 3D network by means of hydrogen bonding. The crystal packing of both complexes is reinforced by π-π interactions between adjacent aromatic rings. The fluorescence study indicates intraligand π-π* charge transfer, which is the reason for emission in both the complexes. 相似文献
8.
The reactions of 2,4-dimethyl-7-(2-pyridylamino)-1,8-naphthyridine (L1) with Zn(ClO4)2 · 6H2O, and bis(5,7-dimethyl-1,8-naphthyrid-2-yl)amine ligand (L2) with Zn(OAc)2 · 2H2O, ZnCl2 or Zn(ClO4)2 · 6H2O afforded four blue luminescent zinc(II) complexes, [Zn(L1)2](ClO4)2 · 2CH2Cl2 (1), [Zn(L2)(OAc)2] · CH2Cl2 (2), [Zn(L2)2][ZnCl4] · 3.5CH2Cl2 (3) and [Zn(L2)2](ClO4)2 (4), respectively. Crystal structures of complexes 1-3 have been determined by X-ray structural analyses as mononuclear complexes with pseudo-tetrahedral geometry. The crystal packing of 1 reveals the coordination cation which is self-assembled to stair chains through aromatic π-π interactions. The intermolecular N-H?O hydrogen bond in 2 generates a centrosymmetric H-bonded dimer. However, the crystal lattice of 3 shows that the molecules are linked by extensive intermolecular hydrogen bonds between the amino groups and the anions, resulting in a one-dimensional zigzag chain. Furthermore, these molecular pairs or chains were self-assembled to two-dimensional sheets or three-dimensional networks through aromatic π-π interactions. All the zinc(II) complexes display intense intraligand 1(π-π∗) fluorescence with λmax at 380 and 393 nm for 1, 385 and 404 nm for 2-4 in methanol at room temperature, respectively. Emission quantum yields of these complexes are in the range from 0.41 to 0.57. The broad emission bands in their solid-state emission spectra are attributed to intraligand 1(π-π∗) transition and aromatic π-π interactions as well. 相似文献
9.
Piotr Buchalski Justyna Chmiel Lucjan B. Jerzykiewicz 《Inorganica chimica acta》2009,362(9):3338-3342
9-Nickelafluorenyllithium (1) reacted with iodine and then with various CpxM complexes (Cpx = Cp, Cp∗, M = Na, Mg, Li) in different solvents. The products (π-allyl complexes), isolated from these reactions, were formed via addition of the biphenyl ligand to the Cp ring originally bonded to the Ni atom. Stereospecifity of the reactions depended on the used solvent. π-Allyl compounds 2, 3 and 4 were characterized by X-ray single crystal analysis. 相似文献
10.
The ruthenium-nitrosyl complexes [RuII(trpy)(tmp)(NO+)](ClO4)3 ([4](ClO4)3) and [RuII(trpy)(tmp)(NO)](ClO4)2 ([5](ClO4)2) with {Ru-NO}6 and {Ru-NO}7 configurations, respectively (trpy = 2,2′:6′,2′′-terpyridine, tmp = 3,4,7,8-tetramethyl-1,10-phenanthroline) have been isotaled. The nitrosyl complexes [4]3+ and [5]2+ have been generated by following a stepwise synthetic procedure: [RuII(trpy)(tmp)(X)]n, X/n = Cl/+ (1+) → CH3CN/2+ (22+) → NO2/+ (3+) → NO+/3+ (43+) → NO/2+ (52+). The single-crystal X-ray structures of two precursor complexes [1]ClO4 and [3]ClO4 have been determined. The DFT optimized structures of 43+ and 52+ suggest that the Ru-N-O geometries in the complexes are linear (177.9°) and bent (141.4°), respectively. The nitrosyl complexes with linear (43+) and bent (52+) geometries exhibit ν(NO) frequencies at 1935 cm−1 (DFT: 1993 cm−1) and 1635 cm−1 (DFT: 1684 cm−1), respectively. Complex 43+ undergoes two successive reductions at 0.25 V (reversible) and −0.48 V (irreversible) versus SCE involving the redox active NO function, RuII-NO+ ? RuII-NO and RuII-NO → RuII-NO−, respectively, besides the reductions of trpy and tmp at more negative potentials. The DFT calculations on the optimized 43+ suggest that LUMO and LUMO+1 are dominated by NO+ based orbitals of around 65% contribution along with partial metal contribution of ∼25% due to (dπ)RuII → π∗(NO+) back-bonding. The lowest energy transitions in 43+ and 52+ at 360 nm and 467 nm in CH3CN (TD-DFT: 364 and 459 nm) have been attributed to mixed MLLCT transitions of tmp(π) → NO+(π∗), Ru(dπ)/tmp(π) → NO+(π∗) and Ru(dπ)/NO(π) → trpy(π∗), respectively. The paramagnetic reduced species 52+ exhibits an anisotropic EPR spectrum with g1 = 2.018, g2 = 1.994, g3 = 1.880 (〈g〉 = 1.965 and Δg = 0.138) in CH3CN, along with 14N (I = 1) hyperfine coupling constant, A2 = 35 G at 110 K due to partial metal contribution in the singly occupied molecular orbital (DFT:SOMO:Ru (34%) and NO (53%)). Consequently, Mulliken spin distributions in 52+ are calculated as 0.115 for Ru and 0.855 for NO (N, 0.527; O, 0.328). The reaction of moderately electrophilic nitrosyl center in 43+ with the nucleophile, OH− yields the nitro precursor, 3+ with the second-order rate constant value of 1.7 × 10−1 M−1 s−1 at 298 K in CH3CN-H2O (10:1). On exposure to light (Xenon 350 W lamp) both the nitrosyl species, 43+ ({RuII-NO+}) and 52+ ({RuII-NO}) undergo photolytic Ru-NO bond cleavage process but with a widely varying kNO, s−1 (t1/2, s) of 1.56 × 10−1(4.4) and 0.011 × 10−1(630), respectively. 相似文献
11.
Soma Mukherjee Chandrama Basu Asoke P. Chattopadhyay Utpal Ghosh 《Inorganica chimica acta》2010,363(12):2752-139
A blue luminescent dichlorido-bridged dinuclear copper(II) (S = 1/2) complex, [CuII2(HL)2(μ-Cl)2]·2H2O, 1a was synthesized with the 1:1 reaction of the acyclic tridentate salicylaldehyde 2-pyridyl hydrazone ligand, HL, 1. The complex 1a displays multiple bands in the visible region (400-470 nm). The association constant (Kass, UV-Vis) was found to be 1.186 × 104 for 1a at 298 K. The copper(II)-copper(III) oxidation potential lies near 0.32 V versus Ag/AgCl electrode. On excitation at 390 nm, the ligand 1 strongly emits at 444 nm due to an intraligand 1(π-π∗) transition. Upon complexation with copper(II) the emission peak is slightly red shifted (λex 390 nm, λem 450 nm, F/F0 0.81) with little quenching. Molecular structure of 1a (Cu···Cu 3.523 Å) has been determined by single crystal X-ray diffraction studies. DFT and TDDFT calculations strongly support the spectral behavior of the ligand and the complex. The complex 1a exhibits a strong interaction towards DNA as revealed from the Kb (intrinsic binding constant) 2.05 × 104 M−1 and Ksv (Stern-Volmer quenching constant) 2.47 values. The complex exhibits cytotoxic effect and the LD50 value for HeLa cells was calculated as 5.44 μM at which the cell cycle was arrested at G2/M phase. 相似文献
12.
John S. Field 《Inorganica chimica acta》2011,374(1):197-204
The synthesis and characterization of [Pt{4′-(p-tolyl)trpy}Cl]SbF6 is described where trpy is 2,2′:6′,2″-terpyridine. A single crystal X-ray structure determination at 100 K shows that the cations are stacked in columns that comprise cations arranged in a staircase motif. Successive cations within a column are linked by π(trpy)-π(phenyl) stabilizing interactions; and each cation in one column is linked to a cation in an adjacent column by a weakly stabilizing Pt···Pt interaction. The Pt···Pt distance is 3.434(1) Å. The metrics governing non-covalent interactions between [Pt{4′-(aryl)trpy}Cl]+ cations have been analyzed for the present structure and related structures in the CSD (Cambridge Structural Database). Cation dimers cluster into three distinct groups based on their lateral shifts and, to a lesser extent, the angular parameters governing their relative displacements; the dominant grouping exhibits Pt···Pt and π(trpy)-π(trpy) stabilizing interactions. An emission spectrum recorded at 77 K on a solid sample of the compound is best interpreted as arising from the decay of three photoexcited states: a 3MLCT (MLCT = metal-to-ligand charge transfer) state; a 3MMLCT (MMLCT = metal-metal-to-ligand charge transfer) state, and an excimeric 3π-π∗ state. 相似文献
13.
Carola S. Vogel 《Inorganica chimica acta》2010,364(1):226-237
The chelating ligand tris-[2-(3-aryl-imidazol-2-ylidene)ethyl]amine (TIMENR, R = aryl = 2,6-xylyl (xyl), mesityl (mes)) has provided access to reactive transition metal complexes. Here, two new tripodal N-heterocyclic carbene ligands of the TIMENR system (R = aryl = tolyl (tol), 3,5-xylyl (3,5xyl)), featuring sterically less demanding aryl substituents were synthesized. With these ligands, Fe(II) precursor complexes could be obtained, namely [(TIMENtol)Fe](BF4)2 (3) and [(TIMEN3,5xyl)Fe(CH3CN)](PF6)2 (7), which showed unexpected reactivity upon reduction. Treatment of the compounds with sodium amalgam yield the tris- and bis-metallated products, [(TIMENtol∗∗∗)Fe] (4) and [(TIMEN3,5xyl∗∗)Fe] (8), respectively. While the Fe(III) complex 4 is relatively inert towards oxygen, the Fe(II) complex 8 is prone to oxidation. This oxidation of 8 can readily be observed in chlorinated solvents, producing the Fe(III) complex [(TIMEN3,5xyl∗∗)Fe](PF6) (9). All new ligand imidazolium precursors and metal complexes were characterized by single crystal X-ray structure determination. 相似文献
14.
Dioxo-MoVI complexes of general formula Tp∗MoO2(p-SC6H4Dn) (6a-6c) (where Tp∗ = hydrotris(3,5-dimethyl-pyrazol-1-yl)borate and Dn = dendritic unit) have been synthesized and characterized by spectroscopy and mass spectrometry. 1H NMR spectra of the metal complexes indicate that the Cs local symmetry about the metal core does not change by the incorporation of dendritic functionality at the thiophenolato ring. Electrochemical data show a ∼20 mV change in the redox potential in the complexes with dendritic ligands suggesting a very small perturbation in the redox orbital, which is also supported by small changes in the electronic spectra. The peak-to peak separation (ΔEp) increases from 125 mV in 6(a) to 240 mV in 6(c), suggesting sluggish electron transfer in molecules with larger dendritic ligands. 相似文献
15.
Self-assembly of Zn(NO3)2·6H2O, 5-amino-2,4,6-triiodoisophthalic acid (H2atiip) and 4,4′-bipyridine (bpy) or 1,3-di(4-pyridyl)propane (dpp) gave rise to three unusual zinc metal-organic frameworks, Zn2(bpy)2(atiip)2·3H2O·2dmf (1), Zn8(dpp)8(atiip)8·4H2O (2), Zn(dpp)(atiip)·(dmf)·(H2O) (3). All complexes possess 2D layer frameworks constructed from 1D Zn-carboxylate tubular unit for 1, 1D Zn-carboxylate helical chain for 2 and 3. In 1 and 2, the bpy or dpp act as both bridging and blocking ligands and the blocking ligands play an important role in the formation of the 2D layer frameworks. Both 2 and 3 contain two different large metallomacrocycles. Photoluminescence measurements of 1-3 in the solid state at room temperature show that all complexes exhibit luminescence, which can be assigned to an intraligand π → π∗ transition or ligand-to-metal charge transfer (LMCT). 相似文献
16.
Diane Marek 《Inorganica chimica acta》2006,359(3):789-799
Two new porphyrins, meso-tris-3,4-dimethoxyphenyl-mono-(4-pyridyl)porphyrin (H2MPy3,4DMPP) and meso-tris-3-methoxy-4-hydroxyphenyl-mono-(4-pyridyl)porphyrin (H2MPy3M4HPP), and their ruthenium analogs obtained by coordination of [Ru(bpy)2Cl]+ groups (where bpy = 2,2′-bipyridine) to the pyridyl nitrogens have been synthesized and studied by electronic absorption spectroscopy, cyclic voltammetry and spectroelectrochemistry. These ruthenated porphyrins couple Ru chromophores to porphyrins containing electroactive meso-substituents. The highest energy electronic absorption for the ruthenated complexes is assigned as a bpy(π) → bpy(π*) intraligand charge transfer while the next lowest energy electronic absorption is assigned as Ru(dπ) → bpy(π*) metal-to-ligand charge transfer (MLCT) transition. The RuIII/II couples occur at approximately 0.95 V versus the SHE reference electrode in acetonitrile solutions. The first oxidation of the porphyrin is localized on the 3,4-dimethoxyphenyl and 3-methoxy-4-hydroxyphenyl substituents, respectively. Electroactive surfaces result from adsorption of these compounds onto glassy carbon electrodes followed by anodic cycling in acidic media. 相似文献
17.
Stereoselective coordination affording a luminescent tcc-isomer of dihalobis(diimine)Co(II) family in which two photoactive diimine ligands (LNO2?) are unsymmetrical and non-equivalent is reported (LNO2? = (E)-3-nitro-N-(pyridine-2-ylmethylene)aniline; ? = dihedral angle between the diimine unit including pyridine ring and the phenyl ring planes; tcc refers trans-cis-cis positions with respect to pyridine nitrogen-imine nitrogen-chloride donors). The single step reaction of 2-pyridinecarboxaldehyde, 3-nitro aniline and anhydrous cobalt dichloride affords only the tcc-(LNO2?1)(LNO2?2)CoIICl2 as the product which is characterized by IR, Mass, UV-Vis spectra and magnetic susceptibility measurements. Single crystal X-ray structure determination has established the orientation of the two ligands in the crystal as (LNO233.7)(LNO279.7)CoIICl2·0.25CH3OH (1). The isomer is luminescent in frozen methanol glass at 77 K with the excitation and emission maxima respectively at 370 and 525 nm. The average luminescence life time is 1.86 ns measured on exciting at 356 nm. Density functional theory (DFT) calculation shows that the non-equivalence of the two diimine ligands prevails in the gas phase also and the geometry is (LNO241.0)(LNO260.5)CoIICl2. The calculation has identified four types of closely spaced localized π∗ orbitals as unoccupied photoactive molecular orbitals (UPMOs). TD-DFT calculations have assigned the Co(II) to π∗ charge transfer (MLCT) and π to π∗ of charge transfer (LLCT) as the primary origin of absorption above 340 nm in methanol. Pendant nitro groups of the ligands and their intermolecular interactions have been the driving force of the stereoselectivity of the product. The binuclear L4Co2Cl4 unit of 1 has constructed the helical 2D assembly and cis-CoCl2 mediated strong inter-helices H-bonding interactions result the channeled 3D framework. Geometry optimization of other possible ttt, ctc, ccc and cct isomers has established that in the gas phase, the tcc-isomer is more stable at least by 20-42 kJ mol−1 compared to other isomers where the two diimine ligands are equivalent. 相似文献
18.
Beatrice Buchin 《Inorganica chimica acta》2006,359(15):4833-4839
The reactions of the Fe(II) and Ru(II) halogenide complexes [Fe(PPh3)2Br2], [Fe(NCCH3)2Br2], [Ru(PPh3)3Cl2], and [Ru(dmso)4Cl2] with GaCp∗ and AlCp∗, respectively, are investigated. The reactions of [FeBr2L2] with ECp∗ exclusively proceed via Cp∗ transfer, leading to [FeCp∗(GaCp∗)(GaBr2)(PPh3)] (1) (L = PPh3, E = Ga), [FeCp∗(GaCp∗)2 (GaBr2)] (2) (L = NCCH3, E = Ga) and [FeCp∗(μ3-H)(κ2-(C6H4)PPh2)(AlCp∗)(AlBr2)] (3) (L = PPh3, E = Al), the latter of which is formed via orthometallation of one PPh3 ligand. The reaction of [Ru(dmso)4Cl2] leads to the homoleptic complex [Ru(GaCp∗)6Cl2] (4) in high yields, while [Ru(PPh3)3Cl2] gives 4 in rather low yields. The reason for this difference in reactivity is investigated and it is shown that Cp∗ transfer and orthometallation are the limiting side reactions of the reaction of [Ru(PPh3)3Cl2] with GaCp∗. All compounds were characterized by NMR spectroscopy, and single crystal X-ray diffraction studies were performed for 1, 3, and 4. 相似文献
19.
Chi-Kwan Li 《Inorganica chimica acta》2005,358(14):4191-4200
A series of phosphinocrown ether-containing gold(I) complexes, [Au(Ph2P-b15c5)Cl] (1), [Au2(μ-i-mnt)(Ph2P-b15c5)2] (2) and [Au2(μ-dtc)(Ph2P-b15c5)2](PF6) (3) (b15c5 = benzo-15-crown-5, i-mnt2− = 1,1-dicyanoethylene-2,2-dithiolate, dtc− = diethyldithiocarbamate) have been synthesized. Complexes 2 and 3 · NaPF6 have also been structurally characterized. The emission bands at ca. 500-515 nm for 2 and 3 upon photo-excitation are tentatively assigned as derived from excited states of S → Au ligand-to-metal charge transfer (LMCT) origin. These complexes have been shown to serve as host for the specific binding of various metal cations. 相似文献
20.
Phosphoryl-transfer reactions have long been of interest due to their importance in maintaining numerous cellular functions. A phosphoryl-transfer reaction results in two possible stereochemical outcomes: either retention or inversion of configuration at the transferred phosphorus atom. When the product is phosphate, isotopically-labeled [16O, 17O, 18O]-phosphate derivatives can be used to distinguish these outcomes; one oxygen must be replaced by sulfur or esterified to achieve isotopic chirality. Conventionally, stereochemical analysis of isotopically chiral phosphate has been based on 31P NMR spectroscopy and involves complex chemical or enzymatic transformations. An attractive alternative would be direct determination of the enantiomeric excess using chiroptical spectroscopy. (S)-Methyl-[16O, 17O, 18O]-phosphate (MePi∗), 7 and enantiomeric [16O, 17O, 18O]-thiophosphate (TPi∗), 10, were previously reported to exhibit weak electronic circular dichroism (ECD), although with 10 the result was considered to be uncertain. We have now re-examined the possibility that excesses of 7 and 10 enantiomers can be detected by ECD spectrometry, using both experimental and theoretical approaches. 7 and both the (R) and (S) enantiomers of 10 (10a, 10b) were synthesized by the ‘Oxford route’ and characterized by 1H, 31P and 17O NMR, and by MS analysis. Weak ECD could be found for 7, with suboptimal S/N. No significant ECD could be detected for the 10 enantiomers.Time-dependent DFT (TDDFT) calculations of the electronic excitation energies and rotational strengths of the same three enantiomers were carried out using the functional B3LYP and the basis set 6-311G∗∗. The isotopically-perturbed geometries were predicted using the anharmonic vibrational frequency calculational code in GAUSSIAN 03. In the case of 10, calculations were also carried out for the hexahydrated complex to investigate the influence of the aqueous solvent. The predicted excitation wavelengths are greater than the observed wavelengths, a not unusual result of TDDFT calculations. The predicted anisotropy ratios are 2.9 × 10−5 for 7, −5.3 × 10−6 for 10a/b, and 1.7 × 10−6 for 10a/b⋅(H2O)6. For 7 the predicted anisotropy ratio approximates that observed in this work, 4.5 × 10−5 at 208 nm. For 10a/b, the upper limits of the experimental anisotropy ratios (<5 × 10−6 at 225 nm, pH 9; <5 × 10−6 at 236 nm, pH 12) are comparable to the predicted magnitude of the value for 10a/b. The lower predicted value for 10a/b · (H2O)6 suggests that the aqueous environment affects the ECD significantly. Altogether, the TDDFT calculations together with a stereochemical analysis based on NMR and the MS data support the conclusion that the experimental ECD results for MePi∗ and TPi∗ may be reliable in order of magnitude. 相似文献