Synthesis and vibrational study of some polydentate ligands

Sodium salts of iminodiacetic acid (IDA), ethylenediaminetetraacetic acid (EDTA), 1,2-propylenediaminetetraacetic acid (PDTA) and 1,2-diaminocyclohexanetetraacetic acid (DCTA) were prepared by modification of the literature methods and their i.r. and Raman spectra were studied. The results obtained by application of both techniques allowed a better characterization of these polydentate ligands. Raman spectroscopy was specially useful in elucidating structural aspects in compounds containing acetate groups.     

Gallane complexes with amido-amine ligands

Gallane complexes bearing amido-amine ligands -N(R)CH2CMe2CH2NMe2 [R = H or SiMe3 (TMS)], (H2Ga[N(H)CH2CMe2CH2NMe2])2, 1, H2Ga[N(TMS)CH2CMe2CH2NMe2], 2, (H(Cl)Ga[N(H)CH2CMe2CH2NMe2])2, 3, ([(TMS)2N](H)Ga[N(H)CH2CMe2CH2NMe2])2, 4, and HGa[N(TMS)CH2CMe2CH2NMe2]2, 5, were synthesized from the reactions of the quinuclidine adducts of mono- and dichlorogallane with the corresponding lithium amides. Structural determinations of compounds 1, 3, and 4 showed all were dimeric with bridging amido groups. Rather than bond to gallium the tertiary amine groups in 1 and 4 were hydrogen-bonded to the amino N-H. In the structure of compound 3 the amine group occupied an axial position in the trigonal bipyramidal geometry of the five-coordinate gallium. The results were rationalized in terms of the steric and electronic properties of gallium ligands.     

Synthesis and study of polydentate ligands that contain a pyrimidine ring

The corresponding hydrazones, azo compounds, and 2,4-bis(1H-pyrazol-1-yl)pyrimidines were synthesized by the reaction of 5-ethyl-2-hydrazino-6-methyl-4(3H)-pyrimidinone, 2-(N-p-butylanilino)-4-hydrazino-6-methylpyrimidine, and 4-hydrazino-2-(1H-pyrazol-1-yl)pyrimidines with salicylaldehyde, isatin, -naphthoquinone, phenanthrenequinone, and acetylacetone. The structures of the synthesized compounds are discussed on the basis of a study of their electronic, IR, and mass spectra.Translated from Khimiya Geterotsiklicheskikh Soedinenii, No. 12, pp. 1682–1687, December, 1980.     

Tetrylenes based on polydentate sulfur-containing ligands

Polydentate SNO-coordinating proligands were obtained by addition of thioacetic acid to conjugated alkene, or ring-opening of thiiranes with organolithium compounds as the key stages. These SNO- and known SNS- and SOS- coordinating proligands were used for the synthesis of tetrylenes by the reaction with Lappert’s tetrylenes E[N(SiMe₃)₂]₂ (E = Ge, Sn), giving polymeric, monomeric or dimeric species depending on the type of the ligand. The structure of stannylenes in solution was analysed by ¹¹⁹Sn NMR spectroscopy.     

Copper(II) complexes of new biomimetic polydentate amide ligands: a spectroscopic study

Complexes of Cu(II) with N,N'-bis(3-carboxy-1-oxopropanyl)-1,2-ethylenediamine(C(10)H(16)N(2)O(6),L(1)), N,N'-bis(3-carboxy-1-oxopropanyl)-1,2-phenylenediamine(C(14)H(16)N(2)O(6),L(2)), N,N'-bis(2-carboxy-1-oxophenelenyl)-1,2-phenylenediamine(C(22)H(16)N(2)O(6),L(3)) and N,N'-bis(3-carboxy-1-oxoprop-2-enyl)-1,2-phenylenediamine(C(14)H(12)N(2)O(6),L(4)) have been prepared and characterised by elemental analyses, vibrational spectra, magnetic susceptibility measurements, ligand field spectra, EPR spectra, thermal studies and X-ray diffraction spectra. Vibrational spectra indicate coordination of amide and carboxylate oxygens of the ligands giving a MO(4) square planar chromophore. Ligand field and EPR spectra support square planar geometry around Cu(II). [Cu(L(1))] complex has the maximum activation energy and [Cu(L(3))] complex has the minimum activation energy.     

Efficient sensitization of lanthanide luminescence by tetrazole-based polydentate ligands

Tetrazolate groups have been included by a convenient synthetic route in diverse ligand topologies, which have allowed the incorporation of lanthanide ions into highly luminescent double- and triple-helical complexes, demonstrating their potential for the expansion of lanthanide chemistry and the development of lanthanide-based applications.     

Chromium chains as polydentate fluoride ligands for lanthanides

Hexametallic chromium(III) chains can act as fluoride donor ligands to lanthanide ions giving {(Cr(6))Ln(x)}(n) complexes; preliminary spectroscopic studies are reported.     

Synthesis,spectroscopic and thermal properties of Pt(II) complexes of some polydentate ligands

The new tetradentate symmetrical (2R,2′S)-1,1′-piperazine-1,4-diyldipropane-2-thiol) (L¹), (2S)-1-[bis(2-aminoethyl)amino]propan-2-ol) (L²), and 2-{(E)-[((1R,2S)-2-{[(1Z)-(2-hydroxy phenyl)methylene]amino}cyclohexyl)imino]methyl}phenol (L³) ligands were synthesized and characterized on the basis of FT-IR, ¹H, ¹³C NMR, EI mass, and elemental analysis. Three commercially available ligands, (2,2′-[ethane-1,2-diylbis(thio)]diethanol (L⁴), 2,2′-dithiodiethanenamine (L⁵), and (2,2′-[ethane-1,2-diyldi(imino)] diethanol (L⁶), were also studied. Pt(II) complexes were characterized by FTIR, elemental analysis and thermal methods. Thermal behaviors of these complexes were investigated in the range 10–1000 °C. Magnetic properties were also studied, and the all complexes were found to be diamagnetic. The structures consist of the monomeric units in which the Pt(II) atoms exhibit square planar geometry. N,N′-bis(salicylidene)-1,2-cyclohexane has been synthesized and characterized by X-ray single crystal diffraction measurement. The ligand crystallizes in monoclinic crystal system and space group, Cc.     

Oxovanadium(IV) complexes with polydentate nitrogen ligands

Summary Biacetyldihydrazone (BdH) and 2,2-6, 2-terpyridine (terpy) complexes of oxovanadium(IV) have been prepared and characterized by chemical analysis, conductance measurements, electronic, i.r. and e.p.r. spectral studies and magnetic susceptibilities measurements. Polymeric and monomer structures are proposed for the BdH and terpy complexes, respectively.     

Synthesis of new chiral thiazoline-containing ligands

New chiral ligands, including bi- and tridentate thiazoline derivatives, analogues of known oxazolines, have been synthesized by a general and convenient procedure, starting from dithioesters and commercial enantiopure 2-aminoalcohols. A preliminary test shows the ability of such ligands to act as asymmetric catalysts in Pd-catalyzed allylic substitution reaction.     

Coordination modes of some fluorinated,potentially polydentate,ligands

Through the use of template condensation reactions, we have developed synthetic routes to a number of fluorinated ligands containing a number of donor atoms in combination with a fluorinated alkoxy group. Typical examples are:

We find all of these to be capable of coordination to transition metals, generally giving stable, neutral, complexes. However, the mode of coordination of (i) and (ii) differs according to the donor atoms present in the chain, with a higher degree of coordination for X = N than for X = O. With ligand (iii), a ‘tripod’ mode of coordination is favoured, with the six donor sites surrounding a 3+ metal ion such as iron(III), cobalt(III), or a lanthanide(III) species.     

New family of polydentate tetrazole-pyrazoline ligands prepared by the azido-Ugi reaction

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Self-assembled polynuclear clusters derived from some flexible polydentate dihydrazide ligands

Polynuclear manganese(II), cobalt(II)/(III), iron(II)/(III) and nickel(II) complexes of a group of flexible polydentate dihydrazone ligands, based on pyridine-2,6-dipicolinic (A), oxalic (B) and malonic (C) subunits are described. Structural details are reported for the linear dinuclear complexes [Ni2(2poap)2(H2O)2](NO3)4 . 2CH3OH . 2.5H2O (1), [Mn2(pttp)(NO3)2(CH3OH)2(H2O)2](NO3)2 . H2O (2) and [Mn2(mapttp)2(NO3)2(H2O)2](NO3)2 . 10H2O (3), a square tetranuclear complex [Co4(pttp)4]Br6 . 9H2O (4), a tetranuclear tetrahedral complex [Ni4(pttp)6](BF4)6F2 . 14H2O (7), and a mixed spin state tetranuclear Ni(II) complex [(2pyoap)2Ni4(CH3OH)4] . 1.5CH3OH (10), with a diamond-like arrangement of metal ions. The paramagnetic metal centers are well separated in each case, leading to weak antiferromagnetic coupling or non-existent spin exchange.     

Synthesis of new dendritic antenna-like polypyridine ligands

An efficient synthesis of multidentate polypyridine ligands, 3,5-bis(2,2??-bipyridin-4-ylethynyl)benzoic acid and 3,5-bis(2,5-bis(2-pyridyl)-pyridin-4-ylethynyl)benzoic acid, with potential application in the production of ruthenium dyes for dye-sensitised solar cells was developed. Isolation of intermediate products and final compounds is simple and the yields are very high. The ligands obtained can be used in the synthesis of dendritic analogues of well known and very efficient N3 dye and ??black dye??.     

Synthesis and characterization of original calix-salen type ligands

Polycondensation reactions between various modified disalicylaldehyde derivatives and two chiral diamines afforded in each case macrocyclic structures, named calix-salen. Mixtures of oligomers (dimers to pentamers) were qualitatively analyzed by Maldi-Tof and ¹H NMR DOSY experiments allowed their easy quantitative investigation. Tuning the reaction conditions and namely the concentration of both monomeric partners led interestingly to the selective preparation of the dimer or the tetramer as main products, in diluted or concentrated media, respectively.     

Luminescent heteroleptic copper(I) complexes with polydentate benzotriazolyl-based ligands

Transition Metal Chemistry - Bis(benzotriazol-1-yl)phenylmethane CHPh(btz)2 and tris(benzotriazol-1-yl)methane CH(btz)3 were used as N-donor ligands to prepare luminescent heteroleptic copper(I)...