SYNTHESIS AND ELECTROCHEMICAL PROPERTIES OF CYCLOPENTADIENYLIRON(II) COMPLEXES WITH BIS(DIPHENYLPHOSPHINO)AMINE AS LIGAND

Abstract

The synthesis and properties of new cationic iron(II) complexes of general formula [(η⁵-C₅H₅)FeL(η²-dppa)]A [A=I^?, L = CO(1); A = BF₄, L = CO(2) CH₃CN(4), η¹-dppa(5); dppa = NH(PPh₂)₂] are described. The carbonyl complex [(η⁵-C₅H₅)Fe(CO)(η²-dppa)]BF₄ is deprotonated to give the neutral complex [(η⁵-C₅H₅)Fe(CO){η²-(PPh₂)₂N}](3). All complexes have been characterized by elemental analysis and IR and NMR spectroscopies. Cyclic voltammetry of complexes 1–5 shows a diverse redox chemistry in acetonitrile solution. While the reduction of 1 and 2 leads to the formation of a dinuclear Fe(I) complex, 4 and 5 form mononuclear species of Fe(I); oxidation of metal centers of 1 and 2 is not observed and in complexes 3 and 4 the metal centers are oxidized at potentials < 1. Complex 5 in acetonitrile solution is transformed into complex 4.     

AN UNUSUAL RUTHENIUM(II) COMPLEX OF 2-(2-PYRIDYL)BENZOTHIAZOLE

Abstract

The ligand 2-(2-pyridyl)benzothiazole (L) can act both as an N-N and an N-S chelating donor. The latter coordination mode is expected to be preferred when it is involved in coordination to Ru(II) which is a soft acceptor centre However, in the title compound, chlorobis(acetonitrile)triphenylphosphino-2-(2-pyridyl)benzothiazole-N,N-ruthenium(II) chlride, [Ru(L)(PPh₃(CH₃CN)₂Cl]Cl, the ligand acts in N,N-bidentate manner and the Ru(II) ion is found to be present in an N₄PCl coordination environment. PPh₃ and Cl are trans to each other and the two CH₃CN ligands occupy cis positions facing the NN donor atoms of ligand L.     

Synthesis, thermal, spectral and magnetic studies of complexes of Co(II), Ni(II), Cu(II), Ru(II), Pd(II) and Pt(II) with 2, 3-disubstituted quinazolin-(3H)-4-ones

A number of complexes of Co(II), Ni(II), Cu(II), Ru(II), Pd(II) and Pt(II) with 2-methyl-3-(carboxy methyl) quinazolin (3H)-4-one (MCMQ) and 2-phenyl-3-(carboxy methyl) quinazolin (3H)-4-one (PCMQ) have been synthesized and characterized by analytical, conductivity, thermal, magnetic, infrared, electronic, proton magnetic resonance and electron spin resonance spectral data. Based on analytical data, the stoichiometry and the association with other molecules of the complexes have been determined. Conductivity data show that all these complexes are nonelectrolytes. Infrared and PMR spectral data indicate that both the ligands are uninegative bidentate with all the metal ions. Based on electronic spectral data, the geometries of the complexes have been indicated. Electronic spectral parameters for Co(II) and Ni(II) and ESR parameters for Cu(II) complexes have been calculated and relevant conclusions have been drawn with respect to the nature of bonds present in them.     

NEW RUTHENIUM(II) COMPLEXES CONTAINING ORGANODISULFIDE LIGANDS

Abstract

The new complexes [CpRu(PPh₃)₂(RSSR)PF₆ R=CH₃, iso-Pr, CH₂C₆H₅ and C₆H₅ have been prepared from the reaction of CpRu(PPh₃)₂Cl with RSSR in CH₃OH in presence of NH₄Cl. This result contrasts with the oxidative additions of RSSR to CpFe(dppe)1 dppe=PPh₂ (CH₂)₂PPh₂ to give [CpFe(dppe)SR]PF₆ (C. Diaz et al., J. Organomet. Chem. 516, 59 (1996)). Huckel calculations on model fragments CpFe(PPh₃)₂ and CpRu(PPh₃)₂ suggest that the higher electron density of iron could explain the differences observed in reactivity. Possible biological implications are discussed.     

联吡啶钌催化的异丙苯自动氧化反应

联吡啶钌[Ru(bpy)₃²⁺]的光化学始于1972年,它是一种理想的进行激发态电子转移反应的试剂。但迄今其作为光氧化反应敏化剂的研究还不多。根据文献报道,认为它是一种单重态氧的敏化剂。     

Synthesis and spectral studies on Co (II) and Ni (II) complexes with polyfunctional quinazoline-(3H)-4-ones

A series of complexes of Co(II) and Ni(II) with 2-(R)-3-(X)-substituted quinazoline-(3H)-4-ones, where R = methyl/phenyl and X = furalamino, uramino and thiouramino have been synthesised and characterised by analytical, conductivity, thermal and magnetic, infrared and electronic spectral data. Based on analytical and conductivity studies the stoichiometries of the complexes have been established. Conductivity data also show that all these complexes are non-electrolytes. Infrared spectral data indicate that all the ligands manifest neutral bidentate with both the metal ions. Geometries for the complexes have been proposed based on electronic spectral data. Various electronic spectral parameters have been calculated for all the complexes and relevant conclusions have been drawn with respect to the nature of bonds present in them.     

RUTHENIUM (II) COMPLEXES IN CATALYTIC OXIDATION

Abstract

Ruthenium (II) complexes of the type RuL(CO)₂Cl₂, [RuL(CO)₂L^? ₂]²⁺ and [RuL(CO)₂Cl L′]⁺ [L = bipyridine (bpy), phenanthroline (phen), biquinoline (biq) and L′ = pyridine (py), 4-chloropyridine (Cl-py), 4-methoxypyridine (MeO-py)] were synthesized from [Ru(CO)₂Cl₂]_n and L, to produce the intermediate RuL(CO)₂Cl₂ followed by hydrolysis and reaction with L′. The catalytic activity of these complexes in epoxidation of olefins with iodosylbenzene under ambient conditions was investigated. A possible mechanism of these reactions, explaining the effects of the ligands on the reaction was explored. At least one carbonyl ligand remained bound to the metal through the reaction. The formation of an oxo intermediate was inferred from spectroscopic detection of bridged oxygen Ru—O—Ru and Ru=O species.     

叠氮二(2,2′-联吡啶)钌(Ⅱ)配合物的光物理和光化学性质

本文研究了叠氮二(2,2′—联吡啶)钌(Ⅱ)配合物在有机溶剂及乙腈—水中的一些光物理和光化学性质。在77K的甲醇—乙醇玻璃态时,用245nm等波长激发表现较强的荧光,其最大发射峰在540nm,另一弱带在580nm。在室温甲醇中测得的磷光发射是弱的,且寿命<15us。 在254nm、300nm及514nm照射下,光反应机制及量子产率与溶剂、照射波长有关。在乙腈—水及乙腈中,分别用254nm和514nm照射均发生取代反应,最后的光产物为Ru(bpy)_2(N_3)(CH_3CN)~ ,配合物消失的量子产率分别为0.129±0.008mol einstein~(-1)及(6.77±0.22)×10~(-5)mol einstein~(-1);在乙腈—水中用514nm照射,生成的光产物先是Ru(bpy)_2(N_3)(CH_3CN)~ ,再生成Ru(bpy)_2(CH_3CN)_2~(2 ),配合物消失的量子产率为(5.32±0.13)×10~(-4)mol einstein~(-1)。     

ZINC(II), CADMIUM(II), MERCURY(II) AND LEAD(II) SEMIQUINONE-TYPE COMPLEXES OF A NEW SCHIFF-BASE LIGAND: ANTIBACTERIAL STUDIES

Abstract

A new Schiff-base ligand LH₂, has been prepared by reaction of 2,9-diformv 1-1,10-phenan-throline with 2,3-diamino-l,4-naphthoquinone. The formation and characterization of complexes of Zn(II), Cd(II), Hg(II) and Pb(II) with the semi-oxidized ligand LH is described. The M(LH)X₂ (X = CI, Br and AcO) radical species are paramagnetic and the observed EPR signals in the solid state at room temperature, with g values close to the electron free g value are proof of the semiquinonic character of the ligand. The antibacterial activity of the ligand and the metal complexes prepared were tested against four bacteria strains and compared with the activity of penicillin.     

CRYSTAL STRUCTURE AND PROPERTIES OF A COPPER(II) COMPLEX OF AN 18-MEMBERED MACROCYCLIC LIGAND WITH N,N' -DICARBOXYLIC ACID ARMS

Abstract

CuL 5H₂O (H₂L = 1, 15-diaza-3, 4; 12, 13-dibenzo-5, 8, 11 -trioxacyclo-octadecane-N,N′-diacetic acid) crystallized from water. Its crystal structure was determined by X-ray diffraction analysis and refined in space group Pnma, a = 20.1784(11), b = 15.8745(9), c = 8.9266(5)Å, V = 2859.4(3)ų, Z = 4, ?(MOKα) = 0.71073, R_W . = 0.0294 for 1822 observed reflection [I > 2[sgrave](I)]. The copper atom is surrounded by two nitrogen atoms, two oxygen atoms from the carboxyl groups in the ligand and one oxygen atom from a coordinated water to form a distorted square pyramidal arrangement. The three ether oxygen atoms in the cycle have no contact with the copper ion.

The stability constant for the 1 :1 complex of copper(II) and protonation constants for the ligand have been determined by potentiometric titration in water (I = 0.1, KNO₃) at 25°C. Electronic spectra, conductivity measurements, thermal analysis, and the EPR of the complex are discussed in terms of the crystal structure.     

NOTE: STRUCTURE OF A COPPER(II) COMPLEX WITH THE MACROCYCLIC LIGAND HEXACYCLEN

Abstract

The saturated macrocyclic ligand 1,4,7,10,13,16-hexaazaoctadecane (hexacyclen, I) exhibits excellent coordination ability^1–5 and extraction properties^6.7 towards different metal ions. Due to the remarkable flexibility of the ligand complexes with different structures are formed.^1–5     

含氮杂茂配体的类茂配合物NpCpTiCl_2催化乙烯聚合研究

茂金属催化烯烃聚合时不仅须大量甲基铝氧烷(MAO)作助催化剂,而且其稳定性较差,结构修饰困难,这都一定程度上限制了茂金属催化剂的发展.近几年来,将非环戊二烯类配体与IVB 族金属作用形成的配合物应用于催化烯烃聚合的研究大量出现[1],其中非环戊二烯配体有脒化物[2,3]、酰胺基[4,5]、NFDA3唑啉[6]、卟啉[7 ]、烷氧基[8]、芳氧基[9～11]、和β-二酮[12,13]、8-羟基喹啉[14～16]等.这些非茂配合物均可催化乙烯或丙烯聚合,但活性都较低.我们曾制备了含配位原子为氧或氮的非环戊二烯基配体的半茂配合物,即茂金属中一个环戊二烯基配体被非环戊二烯基配体取代,使金属中心与一个茂和一个非茂配体配位而形成的桥连或非桥连型的配合物[17,18].这类配合物不仅稳定性好,而且消耗的助催化剂量较少,活性高,对所得聚合物的结构有一定的控制作用.桥连型半茂配合物以“限制几何构型”催化剂为代表[16,19～20 ],非桥连型半茂配合物的报道较少,如CpTi(OiPr)Me2和CpTi(OAr)X2 [21 ,22].我们选择氮杂茂类配体为非环戊二烯阴离子配体,氮杂茂环以一价阴离子的形式与金属中心钛配位,与另一个环戊二烯阴离子形成类茂型配合物.这种类茂配合物易于制备, 稳定性好,而且消耗的助催化剂量较小.     

Palladium(II)-, Platin(II)-, Ruthenium(II)-, Rhodium(III)- und Iridium(III)-Komplexe von Desoxyfructosazin

Metal Complexes of Biologically Important Ligands. CIII. [1] Palladium(II), Platinum(II), Ruthenium(II), Rhodium(III), and Iridium(III) Complexes of Desoxyfructosazine The reactions of the pyrazine derivative desoxyfructosazin(pz) with K₂PtCl₄ and with the chlorobridged [M(PR₃)Cl₂]₂ (M = Pd, Pt), [(η⁵-C₅Me₅)MCl₂]₂ and [(η⁶-p-Cymol)RuCl₂]₂ give the watersoluble complexes cis-Cl₂Pt(pz)₂, (R₃P)(Cl)M(pz)M(Cl)(PR₃) (M = Pd, Pt), (η⁵-C₅Me₅)(Cl)₂M(pz)M(Cl)₂(η⁵-C₅Me₅) (M = Rh, Ir), (η⁶-p-Cymol)(Cl₂)Ru(pz)Ru(Cl)₂(η⁶-p-Cymol).     

Amino-Acid-Induced Circular Polarized Luminescence in One-Dimensional Manganese(II) Halide Hybrid

Circular polarized luminescence (CPL)-active materials attract great attentions owing to their widely applications in 3D optical displays and encrypted transmission. Inspired by the strategies adopted in perovskite based CPL materials, herein, CPL-active hybrids (D)- and (L)-(tert-butyl prolinate)MnCl₃ were successfully prepared by assembling chiral D/L tert-butyl prolinate with manganese (II) chloride. Single crystal structures show the as-formed hybrids possess one-dimensional (1D) structure containing linear chains of face-sharing MnCl₆ octahedral surrounded by prolinate cations. The 1D Mn(II) hybrids display strong red emission peaked at 646 nm with PLQY of 67.1 % and 57.2 % for d -type and l -type, respectively, representing the highest PLQY for 1D Mn^II hybrids. Interestingly, the 1D Mn(II) hybrids exhibit prominent circular dichroism (CD) signals and remarkable CPL activity with the dissymmetry factor g of 6.1*10⁻³ and −6.3*10⁻³ from 550 to 800 nm for (D)- and (L)-(tert-butyl prolinate)MnCl₃, respectively, owing to the existence of chiral cations. It is worthy noted the obtained g represents the highest value for non-lead organic–inorganic hybrids.     

Manganese (II) complexes of some nitrogen-oxygen and nitrogen-sulphur donor ligands

Manganese(II) complexes of the general composition, Mn(L)₂X₂ (X = Cl or 1/2 SO₄,L = semicarbazones and thiosemicarbazones of acetone, ethyl methyl ketone and 2-methyl cyclohexanone) have been prepared and characterised by elemental analysis, magnetic moments, conductance measurements, IR, electronic and ESR spectral studies. All the complexes are six-coordinate octahedral.     

Reversible catenation of coordination rings with Pd(II) and/or Pt(II) metal centers: Chirality induction through catenation

A Pd(II)-linked coordination ring is reversibly transformed into its catenanted dimer at room temperature through the efficient organic stacking of the component rings. An analogous Pt(II)-linked ring is also catenated only at high temperature (100 °C), but not at room temperature because of the kinetic inertness of Pt(II)-ligand interaction. Interestingly, the combination of the Pd(II)- and the Pt(II)-linked coordination rings selectively gives a Pd(II)/Pt(II) cross-catenane, because the kinetically inert Pt(II) ring can be catenated only via the dissociation of the kinetically labile Pd(II) ring. Planer conformation of the monomer rings is twisted upon catenation, inducing helical chirality in the catenated structure. Thus, induced circular dichroism (ICD) is observed in the catenation when chiral-1,2-cyclohexandiamine is attached as a chiral auxiliary on the metal centers. The ICD decreases with increasing temperature due to less effective chiral aromatic stacking at higher temperature. The Pd(II) ring shows higher ICD than the Pt(II) ring, probably due to the more flexible conformation of the Pd(II) ring that can adopt chiral orientation easily. © 2003 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem 41: 3478–3485, 2003     

A NEW CYCLOBUTANE SUBSTITUTED SCHIFF BASE LIGAND,SYNTHESIS OF ITS Cd(II), Co(II), Cu(II), Ni(II) AND Zn(II) COMPLEXES AND INVESTIGATION OF THEIR STRUCTURE

Abstract

A new, thiazole derivative ligand, 4-(1-phenyl-1-methylcyclobutane-3-yl)-2-(2-hydroxy-5-bromo benzylidenehydrazino) thiazole (LH), has been synthesized by the reaction of 2-hydroxy-5-bromobenzaldehyde, thiosemicarbazide and subsequently 1-phenyl-1-methyl-3-(2-chloro-1-oxoethyl) cyclobutane. Mononuclear complexes with a metal-ligand ratio of 1 : 2 have been prepared with Cd(II), Co(II), Cu(II), Ni(II) and Zn(II). The authenticity of the ligand and its complexes was established by elemental analyses, IR, ¹³C and ¹H NMR spectra, magnetic susceptibility measurements and thermogravimetric analyses (TGA) and differential scanning calorimetry (DSC).     

Triple Helicates with Golden Strands: Self‐Assembly of M2Au6 Complexes from Gold(I) Metallaligands and Iron(II), Cobalt(II) or Zinc(II) Cations

Alkynyl gold(I) metallaligands [(AuC≡Cbpyl)₂(μ‐diphosphine)] (bpyl=2,2′‐bipyridin‐5‐yl; diphosphine=Ph₂P(CH₂)_nPPh₂, [n=3 (L^Pr), 4 (L^Bu), 5 (L^Pent), 6 (L^Hex)], dppf (L^Fc), Binap (L^Binap) and Diop (L^Diop)) react with MX₂ (M=Fe, Zn, X=ClO₄; M=Co, X=BF₄) to give triple helicates [M₂(L^R)₃]X₄. These complexes, except those containing the semirigid L^Binap metallaligand, present similar hydrodynamic radii (determined by diffusion NMR spectroscopy measurements) and a similar pattern in the aromatic region of their ¹H NMR spectra, which suggests that in solution they adopt a compact structure where the long and flexible organometallic strands are folded. The diastereoselectivity of the self‐assembly process was studied by using chiral metallaligands, and the absolute configuration of the iron(II) complexes with L^Binap and L^Diop was determined by circular dichroism spectroscopy (CD). Thus, (R)‐L^Binap or (S)‐L^Binap specifically induce the formation of (Δ,Δ)‐[Fe₂((R)‐L^Binap)₃](ClO₄)₄ or (Λ,Λ)‐[Fe₂((S)‐L^Binap)₃](ClO₄)₄, respectively, whereas (R,R)‐ or (S,S)‐L^Diop give mixtures of the ΔΔ‐ and ΛΛ‐diastereomers. The ΔΔ helicate diastereomer is dominant in the reaction of Fe^II with (R,R)‐L^Diop, whereas the ΛΛ isomer predominates in the analogous reaction with (S,S)‐L^Diop. The photophysical properties of the new dinuclear alkynyl complexes and the helicates have been studied. The new metallaligands and the [Zn₂(L^R)₃]⁴⁺ helicates present luminescence from [π→π*] excited states mainly located in the C≡Cbpyl units.     

SYNTHESIS AND CHARACTERIZATION OF A SERIES OF LIPOPHILIC CISPLATIN ANALOGS WITH CIS-1,4-DIAMINOCYCLOHEXANE AS NONLEAVING AMINE LIGAND

Abstract

A series of lipophilic platinum(II) complexes of the type [Pt(cis-1,4-DACH)L₂] (where cis-1,4-DACH = cis-1,4-diaminocyclohexane and L = acetate, propionate, butyrate, valerate, hexanoate, heptanoate, octanoate, 2,2′-dimethyloctanoate, nonanoate, decanoate, undecanoate, laureate, tridecanoate, myristate, pentadecanoate, palmitate, heptadecanoate, stearate, nonadecanoate, or eicosanoate) has been synthesized and characterized by elemental analysis and by infrared, ¹³C, and ¹⁹⁵Pt nuclear magnetic resonance spectroscopic techniques.     

Electronic Circular Dichroism Imaging (ECDi) Casts a New Light on the Origin of Solid-State Chiroptical Properties

Solid-state ECD (ss-ECD) spectra of a model microcrystalline solid, finasteride, dispersed into a KCl pellet were recorded by using the synchrotron radiation source at the Diamond B23 beamline. Scanning a surface of 36 mm² with a step of 0.5 mm, we measured a set of ECD imaging (ECDi) spectra very different from each other and from the ss-ECD recorded with a bench-top instrument (1 cm² area). This is due to the anisotropic part of the ECD (ACD), which averages to zero in solution or on a large number of randomly oriented crystallites, but can otherwise be extremely large. Two-way singular value decomposition (SVD) analysis, through experimental and simulated TDDFT spectra, disclosed that the measured and theoretical principal components are in line with each other. This finding demonstrates that the observed isotropic ss-ECD spectrum is governed by the anisotropy of locally oriented crystals. It also introduces a new quality for ss-ECD measurements and opens a new future for probing and mapping chiral materials in the solid state such as active pharmaceutical ingredients (APIs).