SOME REGULARITIES IN THE SYNTHESES AND STRUCTURE OF LINEAR MOLYBDENUM-IRON-SULFUR CLUSTER COMPLEXES

Linear Mo-Fe-S cluster complexes with basic unit of MoS_4 can be divided into four types ac-cording to the central Mo-S skeleton (S_2MoS_2Fe, S_2MoS_2FeS_2MoS_2, S_2MoS_2FeS_2Fe, FeS_2MoS_2Fe).Ten such complexes with various ligands and cations were synthesized, and their crystal structureswere determined and characterized by electron spin resonance, infrared and electron absorptions,Mossbauer and magnetic effects. Atomic distances from crystallographic analysis were comparedsystematically with respective spectroscopic data. There is strong evidence indicating that electrontransfers from Fe(Ⅱ) to Mo(Ⅵ), in spite of the fact that the apparent oxidation state of molyb-denum in most of the aforementioned complexes remains six. The probability of this electrontransfer depends strongly on the environment of Fe(Ⅱ). The fact that MoS_4~(2-) is both a goodbidentate ligand and an effective electron transfer unit is also evidence for its presence in manymolybdoenzymes and as a catalytically active center.     

STABILITY OF POLY(N,N''''-METHYLENEBISACRYLAMIDE-co-4-VINYLPYRIDINE)MICROGEL DISPERSION AND ADJUSTMENT OF THE HYDROPHOBICITY IN THE MICROGELS

In the UV-Vis spectra of pure light-scattering systems,there is an exponential relationship between absorbance and wavelength(A=Kλ~(-n)).Here,the exponent n is named as flocculation-coagulation parameter.In the present paper,the effects of different additives on the stability of poly(N,N'-methylenebisacrylamide-co-4-vinylpyridine)(poly(Bis-co-4-VP)) microgel dispersion were studied in detail via this parameter.The results showed that the stability of the dispersion mainly comes from the ionization of pyridine groups,making the microgel positively charged on its surface.This was confirmed by the measurement of Zeta potential and the result of conductometric titration.The result of fluorescence analysis indicated that the hydrophobicity in the microgels is enhanced with the increase in total 4-VP unit content.     

THE CHIRAL SELECTIVITY IN ACROSS－MEMBRANE TRANSPORT OF 1，2－DIAMINOCYCLOHEXANE PLATINUM（II）COMPLEXES AND THE CONTRIBUTION OF LEAVING GROUPS

ＴＨＥＣＨＩＲＡＬＳＥＬＥＣＴＩＶＩＴＹＩＮＡＣＲＯＳＳ－ＭＥＭＢＲＡＮＥＴＲＡＮＳＰＯＲＴＯＦ１，２－ＤＩＡＭＩＮＯＣＹＣＬＯＨＥＸＡＮＥＰＬＡＴＩＮＵＭ（ＩＩ）ＣＯＭＰＬＥＸＥＳＡＮＤＴＨＥＣＯＮＴＲＩＢＵＴＩＯＮＯＦＬＥＡＶＩＮＧＧＲＯＵＰＳ￥...     

STABILITY OF POLY（N,N＇-METHYLENEBISACRYLAMIDE-co-4-VINYLPYRIDINE） MICROGEL DISPERSION AND ADJUSTMENT OF THE HYDROPHOBICITY IN THE MICROGELS

In the UV-Vis spectra of pure light-scattering systems, there is an exponential relationship between absorbance and wavelength （A = Kλ^-n）. Here, the exponent n is named as flocculation-coagulation parameter. In the present paper, the effects of different additives on the stability of poly（N,N＇-methylenebisacrylamide-co-4-vinylpyridine） （poly（Bis-co-4-VP）） microgel dispersion were studied in detail via this parameter. The results showed that the stability of the dispersion mainly comes from the ionization of pyridine groups, making the microgel positively charged on its surface. This was confirmed by the measurement of Zeta potential and the result of conductometric titration. The result of fluorescence analysis indicated that the hydrophobicity in the microgels is enhanced with the increase in total 4-VP unit content.     

APPLICATIONS OF DSCPCF MODEL IN RARE EARTH COMPLEXES (Ⅳ)——ANALYSIS OF ABSORPTION SPECTRA FOR Pr~(3+)- AND Tm~(3+)-2-THENOYLTRIFLUOROACETONE-PIPERIDINE COMPLEXES

The new complexes, RE(TTA)_4·HP(RE are Pr~(3+) and Tm~(3+)), have been prepared, and their UV-VIS-NIR absorption spectra measured. All the matrix element formulas of f~2 and f~(12) configurations in D_4 symmetry field have been derived with the Double Sphere Coordination Point Charge Field Model, and the influence of the symmetry change of the complex unit, REO_3, on the forbital levels of Pr~(3+) is discussed. And based on the theoretical calculations, the transition peaks in the absorption bands are assigned.     

DETERM INATION OF THE STABILITY CONSTANTS OF COMPLEXES OF HISTIDINE,SOME DIPEPTIDES AND TRIGLYCINE WITH Zn(Ⅱ)AND Cd(Ⅱ)USING SMALL-SCALE PH-METRIC TITRATIONS

A potentiometric study on the complexes of His,Gly-His,ALa-His,Gly-Gly andGly—Gly—Gly with Zn(Ⅱ)and Cd(Ⅱ)has been reported.Small-scale potentiometric titrations were car-ried out to determine stabil ity constants of complexes at 25℃ with I=0.10 mol dm~(-3)(KNO_3).The com-puter programs SUPERQUAD were applied for data treatment with satisfactory results.     

THE INFRARED SPECTRA (4000 - 50 cm−1) OF COMPLEXES OF QUINOLINE N-OXIDE AND ITS PERDEUTERATED ANALOGUE WITH METAL(II) PERCHLORATES OF THE FIRST TRANSITION SERIES

Abstract

Infrared assignments (4000 - 50 cm^?1) are presented for the complexes [M(quinO)_n](ClO₄)₂(quinO = quinoline N-oxide; n = 6 for Mn, Co, Ni; n = 5 for Zn, and n = 4 for Cu) and their perdeuterated analogues. The spectra are consistent with octahedral structures for the 6-coordinate complexes, a trigonal bipyramidal structure for the Zn(II) complex and a square planar structure for the Cu(II) complex, with some distortion from idealised symmetry evident for each complex. In the Mn(II) complex, strong coupling occurs between the vM-O of lowest frequency and the ligand vibration, xN-O (mode 45). In the Cu(II) complex, the single vCu-O is strongly coupled with the ring torsion (mode 28).     

SYNTHESIS OF BENZO[1,2-b: 5,4-b′]- DIFURANYL-TRIAZOLES, -OXADIAZOLES, -THIAZOLIDINONES, -THIADIAZOLES,AND THE USE OF DNA IN EVALUATION OF THEIR BIOLOGICAL ACTIVITY

Benzo[1,2-b:5,4-b′]difuran-2-carbohydrazides 5a, b were reacted with aryl or alkyl isothiocyanates to give the corresponding thiosemicarbazides 6a–h. Cyclization of the substituted thiosemicarbazides with sodium hydroxide led to the formation of benzo[1,2-b:5,4-b′]difuranyl-1,3,4-triazoles 7a–f. Desulfurization of thiosemicarbazides by mercuric oxide gave benzo[1,2-b:5,4-b′]difuranyl-1,3,4-oxadiazoles 8a–f. Treatment of thiosemicarbazides with ethyl bromoacetate or α-bromopropionic acid yielded benzo[1,2-b:5,4-b′]difuranyl-carbonyl-hydrazono-4-thiazolidinones 9a–f and 10a–f, respectively. Furthermore, the reaction of the thiosemicarbazides with phosphorus oxychloride gave benzo[1,2-b:5,4-b′]difuranyl-1,3,4-thiadiazoles 11a–f. Some compounds in this study were biologically evaluated for their ability to bind to DNA.     

SYNTHESIS, CHARACTERIZATION OF IMIDAZOLATE-BRIDGED HETEROPOLY- NUCLEAR COMPLEXES AND THEIR ACTIVITY IN DISMUTATION OF O~(-)_(2)

A series of imidazolate-bridged heteropolynuclear complexes containing Cu2+ or Zn2+ were synthesized and characterized by reflectance spectroscopy, NMR and X-ray diffraction analysis. The bonding nature and the stability of imidazolate bridges in the complexes were studied by ESR spectroscopy, and the catalytic activity of the complexes in dismutation of O-2 was determined by NBT method. Results obtained indicate that the central Cu with N4 and N2O2 square planar or N4O square pyramidal coordination in which there is a weak bond H2O or ClO-4 on axial position, has a comparatively higher activity, but that with N5 square pyramidal having a strong bond axial ligand has almost no activity. Thus the results imply a possible formation of Cu-O-2 intermediate adduct in the catalytic process by Cu, Zn-SOD.     

SYNTHESIS,LASER-RAMAN,INFRARED AND PROTON MAGNETIC RESONANCE SPECTRA OF (CH3)3PtX2- 3 IONS (X = Cl−, Br−) AND (CH3)3Ptiv ISOCYANIDE COMPLEXES

Abstract

The novel ionic complexes [(C₆H₅)₄As]₂ [(CH₃)₃PtX₃](X = Cl^? and Br^?) and [(CH₃)₃Pt(bipy)L]⁺[B(C₆H₅)₄]^? (bipy = 2,2′-bipyridine, L = aliphatic and aromatic isocyanide) have been prepared. The structure of the complex ions has been inferred from Laser-Raman and infrared spectra in the solid state and ¹H NMR in solution. These data are consistent with a facial configuration of the organometallic moiety. Trends in vibrational frequencies ν(Pt-C) and ν(Pt-X) indicate a “trans” influence sequence for the ligands, which in the case of (CH₃)₃PtX^2- ₃ is related with that found for (CH₃)₂AuX^? ₂ ions.     

THE APPLICATION OF N,N′DIBROMO-N,N′-1,2-ETHANEDIYL BIS(P-TOLUENESULFONAMIDE) AS A POWERFUL REAGENT FOR CONVERSION OF CARBOXYLIC ACIDS INTO ESTERS AND AMIDES WITH TRIPHENYLPHOSPHINE

In the presence of equivalent amounts of triphenylphenylphosphine and N,N′-dibromo-N,N′-1,2-ethanediylbis(p-toluenesulphonamide) ester and amide compounds can be generated in high yields from the corresponding carboxylic acid and alcohols or amines.     

BINDING ABILITY OF OXINE-LIKE LIGANDS. POTENTIOMETRIC AND POLAROGRAPHIC STUDY ON Ni(II), Co(II), Zn(II) AND Cd(II) COMPLEXES OF 9-HYDROXYPYRIDO(1,2,-α)PYRIMIDIN-4-ONE

Abstract

Potentiometric and polarographic studies of metal ion coordination with 9-hydroxypyrido[1,2-α]pyrimidin-4-one (HPP) with Ni(II), Zn(II), Co(II) and Cd(II) ions have been carried out. For comparison, stability constants with 8-hydroxy-imidazo[1,2-α]pyridine (HIP) were also measured. Due to the low solubility of the latter ligand complexes, measurements were made also in dioxan/water solutions. In the case of both ligands the coordination mode is the same. The oxine-like binding via {N, O^?} donor set leads to formation of stable ML and ML₂ complexes. Stability constants clearly indicate that both ligands are very effective and the HPP, having a more favourable position of the electron pair on nitrogen, forms stronger complexes with smaller metal ions i.e., Ni(II), Zn(II) and Co(II). Cd(II) is better fitted to the HIP donor set.     

BINUCLEAR COPPER(Ⅱ) COMPLEXES OF SOME PLANT GROWTH-STIMULATING SUBSTANCES Ⅱ. SYNTHESES AND STRUCTURES OF BIS(N,N-DIMETHYLFORMAMIDE)-TETRAKIS-[μ-(N-p-(AND m-)METHYLPHENYLPHTHALAMINO)]DICOPPER(Ⅱ)TETRAKIS(N,N-DIMETHYLFORMAMIDE) SOLVATE

<正> [Cu2( -C-N-C6H4CH3-p)4(DMF)2]-4DMF(1), Mr = 1582.7, triclinic,Pl, a = 10.761(1), b = 13.930(3), c = 15.116(3) A;α= 114.74(1),β= 101.82 (1),r= 95.85(1)°,V = 1969.0 A3,Z=1,Dm= 1.36,DC =1.335 g/cm3.[Cu2(-C-N-C6H4Ch3-M)4.(DF)2].4DMF(2), Mr = 1582.7, triclinic, Pl,a = 10.588(5), b = 13.699(2), c = 15.759(4) A;α= 114.88(2),β= 103.89(3), γ=92.56(3)°, V =1985.3 A3, Z = 1, 0. = 1.39,Dc= 1.324 g/cm3.The four phthalamine groups in molecules of (1) and (2) are all biden-tate bridging ligands to Cu atoms and there are two terminal DMF ligands, one on each Cu atom. The Cu-Cu distances are 2.635(1) and 2.641(1) A for (1) and (2) respectively.     

CRYSTAL STRUCTURE INVESTIGATION OF VANADYL COMPLEXES OF TRIDENTATE LIGAND (Ⅰ)——THE CRYSTAL STRUCTURES OF BIS[(1-(2,4-PENTANE- DIONATO(NITROBENZOYL) HYDRAZONE)-2- ETHOXY)OXOVANADIUM] AND BIS-[(1-(2, 4-PENTANEDIONATO-(3-NITROBENZOYL) HYDRAZONE)-2- METHO

The title complexes were obtained by the reactions of bis(2,4-pentanedionato)oxovanadium VO(Acac)_2 and m-nitrophenylhydrazide m-NO_2PhCONHNH_2 in the media EtOH and MeOH respectively. The compound (Ⅰ) crystallizes in the space group PT with unit cell dimensions a=8.123(2), b=10.409(5), c=10.822(4), α=65.78(3)°, β=85.50(3)°,γ=89.04(3)°. The compound (Ⅱ) crystallizes in the space group P2_1/a with unit cell dimensions a=7.745(2), b=19.164(5), c=10.787(4), β=107.87(2)°. The resuhs of structural analyses show that the two compounds have the same characteristics: the tridentate ligand formed by condensation occupies three of the four equatorial positions of vanadium and the rest equatorial position is occupied by alkoxy group RO~-. As RO~-group also bridges the sixth coordinated position of each vanadium atom, it brings about the formation of the new type binuclear complexes of vanadium.     

STEREOSELECTIVITY ON ELECTRON TRANSFER REACTIONS(I); REACTION OF THE Λ-[Co(EDDS)]− AND RAC-[Co(DIAMINE)3]2+ COMPLEXES (DIAMINE = EN,CHXN)

Abstract

The absolute configuration of an optically active Λ-[Co(EDDS)]^? (EDDS = ethylene-diaminedisuccinate) complex was determined as Λ by the regional rule and spectroscopic data. The stereoselective ionic association between Λ-[Co(EDDS)]^? and rac-[Co(en)₃]³⁺ occurs preferentially between Λ-[Co(EDDS)]^? and δ-[Co(en)₃]³⁺. The stereoselective electron transfer reaction between Λ-[Co(EDDS)]^? and rac-[Co(en)₃]²⁺ has been investigated in aqueous solution, DMF and DMSO. Their enantiomeric excesses (e.e.) observed are 14%, 26% and 40% of δ-[Co(en)₃]³⁺, respectively. The electron transfer reaction between Λ-[Co(EDDS)]^? and conformationally restricted [Co(chxn)₃]²⁺ has been examined in aqueous and DMSO solution. In aqueous solution, there are four isomers in the product which were determined as lel₃, lel₂ob, lelob₂ , and ob₃ of δ-[Co(chxn)₃]³⁺ with optical purities of 22%, 25%, 11% and 10% e.e. respectively. In DMSO, the reaction produces lel₃ -δ-and lel₂ob-δ-[Co(chxn)₃]³⁺ with optical purities of 100% and 75% e.e. respectively.     

CHIRAL METAL COMPLEXES. 30 THE CRYSTAL AND MOLECULAR STRUCTURES OF A-β-[DINITRO{N,N′-BIS(2-PICOLYL)-lR,2R-DIAMINOCY CLOHEXANE}COBALT(III)] PERCHLORATE MONOHYDRATE,AND α-β-EXO-[DINITRO{ 3R-METHYL-1,6-BIS(2-PYRIDYL)-2,5-DIAZAHEXANE}COBALT(III)] PERCHLORATE MONOHYDRATE

Abstract

The structures of two Co(III) complexes containing N-bonded nitrite ions and one of the N⁴ tetradentate ligdnds R,R-picchxn (N,N'-bis(2-picolyl)-1 R,2R-diaminocyclohexane) or R-picpn (3R-methyl-1,6-bis(2-pyridyl)-2.5-diazahexane) have been determined by X-ray analyses. A-β-[Co(R,R-picchxn)(NO₂)₂1 CLO₄,.H₂O is triclinic. space group P1, with a = 8.611(2), b = 9.188(1), c = 8.576(1) Å, α = 117.60(1), β = 96.40(1). γ = 73.69(1)° and Z = 1. The structure ivas refined by full-matrix least-squares methods to R = 0.035 for 2712 non-zero reflexions. δ-β-eso-[Co(R-picpn) NO₂)₂]CIO₄,.H₂O is orthorhombic, space group P2₁2₁2₁. with a = 7.664(1). b = 15.121(3). c = 18.429(4) a and Z = 4. The structure was refined as above to R = 0.040 for 2063 non-zero reflexions. In the R.R-picchxn complex both amine nitrogen atoms of the tetradentate have the same relative configuration, Hhereds in the R-picpn diastereoisomer their relative configurations are opposite. In the latter complex this permits the exo methyl group substituent to adopt a nearly ideal equatorial position in the central chelate ring. Hydrogen bonding networks in the two structures. which link the complex cations to the perchlorate ions and lattice water molecules, are apparent.     

HYDROGEN BONDING IN THE CRYSTAL OF 1,1′-((1E,1′E)-(PYRIDINE-3,4-DIYLBIS (AZANYLYLIDENE))BIS(METHANYLYLIDENE))- BIS(NAPHTHALEN-2-OL) ACETONITRILE SOLVATE: COMBINED EXPERIMENTAL AND THEORETICAL STUDY

Journal of Structural Chemistry - The title compound, 1,1′-((1E,1′E)-(pyridine-3,4-diylbis(azanylylidene))bis(methanylylidene))bis (naphthalen-2-ol) (1), was synthesized and...     

A NOVEL REACTION BETWEEN [μ-PhC(O)S]-(μ-RS)Fe_2(CO)_6 AND (μ-R~1S)(μ-XMgS)Fe_2(CO)_6——THE SYNTHESIS, CHARACTERIZATION AND FORMATION MECHANISM OF TWIN CLUSTER COMPLEXES [(μ-RS)Fe_2(CO)_6](μ_4-S)[(μ-R~1S)Fe_2(CO)_6]

The reaction of (μ-RS)(μ-XMgS)Fe_2(CO)_6 with PhC(O)Cl gave four new benzoyl complexes [μ-PhC(O)S](μ-RS)Fe_2(CO)_6(R=Me, Et, n-Bu, CH_2=CHCH_2), which further reacted with (μ-R~1S)(μ-XMgS)Fe_2(CO)_6 to afford eight new twin cluster complexes with the general formula of [(μ-RS)Fe_2(CO)_6](μ_4-S)[(μ-R~1S)Fe_2(CO)_6]. The single crystal X-ray analysis for one of these complexes (R=n-Bu, R~1=Ph) showed that it consists of two different moieties PhSFe_2(CO)_6 and n-BuSFe_2(CO)_6 joined together through the spiran type of μ_4-S., The complex belongs to space group P-1; cell parameters are a=9.028(3), b=10.386(1), c=16.723 (5); α=87.70(2)°,β=75.67(2)°, r=82.26(2)°; z=2, Dx=1.743 g/cm~3. Final deviation factor R=0.031.