Synthesis and characterization of polymerizable β-diketone-based liquid crystalline metal chelates

Two novel square-planar palladium chelating liquid crystals, bis(p-n-(l-undecenoxyphenyl-3-dodecyloxyphenyl)-propane-1,3-dionato)palladium(II) (Pd-C₁₁-C₁₂) and bis(1,3-di(p-n-tetradecyloxphenyl)-propane-1,3-dionato) palladium (II) (Pd-C₁₄-C₁₄) have been synthesized. Moreover, the copper chelating liquid crystal bis(p-n-(l-undecynoxylphenyl-3-dodecyloxylphenyl)-propane-1,3-dionate)copper (II) (Cu-Cu₁₁-C₁₂) has been synthesized by heterogeneous ligand-exchange reaction. These β-diketone metal chelates have been characterized by elementary analysis, differential scanning calorimetry, polarizing microscopy, X-ray diffraction analysis and temperature-variable IR. It was found that these chelates were discotic lamellar-(D_L) mesophase liquid crystals. In particular, the temperature-variable IR study indicates that the central chelating ring and the surrounding benzene rings would form a co-planar conjugated structure in the liquid crystalline (LC) state.     

Properties of liquid-crystalline copper(II) complexes and their binary mixtures

Abstract

Eight new copper compounds with mesogenic properties from the series of the bis{1-[4-trans-(4-alkylcyclohexy1)phenyl]-alkylpropane-1,3-dionato} copper(II) complexes have been prepared. The thermal behaviour of these compounds was investigated by means of polarizing microscopy and differential scanning calorimetry (D.S.C.) measurements. The mesophase, which could be found in most of them, is of the monotropic nematic type. This has been confirmed by miscibility experiments. The physical data of a binary mixture with an enantiotropic mesophase are also presented. In addition the crystal structures of two of the compounds are reported.     

The dynamic stereochemistry of the allylic ligand in a μ-allylic complex of platinum(II)

¹H NMR studies of an equilibrium mixture of 1,1,1,5,5,5-hexafluoropentane-2,4-dionato-π-allylplatinum(II) [IA] and bis(1,1,1,5,5,5-hexafluoropentane-2,4-dionato)bis(μ-allyl)diplatinum(II) [IB] show that the μ-allylic ligands of (IB) exhibit temperature dependent tautomeric behaviour, giving rise to a site-exchange between protons on these ligands.     

Allgemeiner Zugang zu Polyaminen mit Ethan-1,2-diamin-Einheiten: Synthese von nicht natürlich vorkommenden homologen und isomeren N1,4-Di(4-cumaroyl)sperminen

█tl="American"█The synthesis of the three N,N′-di(4-coumaroyl)tetramines, i.e., of (E,E)-N-{3-[(2-aminoethyl)amino]propyl}-3,3′-bis(4-hydroxyphenyl)-N,N′-(ethane-1,2-diyl)bis[prop-2-enamide] ( 1a ), (E,E)-N-{4-[(2-aminoethyl)amino]butyl}-3,3′-bis(4-hydroxyphenyl)-N,N′-(ethane-1,2-diyl)bis[prop-2-enamide] ( 1b ), and (E,E)-N-{6-[(2-aminoethyl)amino]hexyl}-3,3′-bis(4-hydroxyphenyl)-N,N′-(ethane-1,2-diyl)bis[prop-2-enamide] ( 1c ), is described. It proceeds through stepwise construction of the symmetric polyamine backbone including protection and deprotection steps of the amino functions. Their behavior on TLC in comparison with that of 1,4-di(4-coumaroyl)spermine (=(E,E)-N-{4-[(3-aminopropyl)amino]butyl}-3,3′-bis(4-hydroxyphenyl)-N,N′-(propane-1,3-diyl)bis[prop-2-enamide]; 2 ) is discussed.     

Discotic metallomesogens: Synthesis and properties of square planar metal bis(β-diketonate) complexes

Abstract

Discotic β-diketonate liquid crystals containing palladium(II), and oxovanadium(IV), (V[tbnd]0), analogous to known copper complexes (which display discotic lamellar and columnar mesophases), have been prepared and characterized. These are the first enantiotropic discotics containing Pd(II) and among the earliest examples containing VO(IV). The best-behaved Pd(II) complex is [Pd(DK 10, 10)₂], and it also is probable that the complexes [Pd(DKn,n)₂] (n = 7–9) are mesomorphic, however their characterization is difficult due to decomposition in the isotropic phase. The mesophase of [Pd(DK 10²,10²)₂], which appears below 100°C, is suggested to be an example of the rare N_d phase on the basis of optical microscopy. The complex [VO(DK8,8)₂] is an enantiotropic discotic vanadyl complex; the monotropic behaviour of [VO(DK 10,10)₂] was also confirmed. It is suggested that the discotic phase which occurs for [VO(DK 8,8)₂] is more organized than that of [Cu(DK 8,8)₂].     

Structure and properties of bis{[2-(4-<Emphasis Type="Italic">tert</Emphasis>-butyl)phen]ethyl}phosphine sulfide

Previously unknown bis[2-(4-tert-butyl)phen]ethylphosphine sulfide is obtained with a high yield from 4-tert-butyl styrene, red phosphorus, and elemental sulfur. Using single crystal XRD, multinuclear NMR, IR, and UV spectroscopy, it is found that the phosphorus atom is four-coordinated in the bis[2-(4-tert-butyl)phen]ethylphosphine sulfide molecule (regardless of the phase state of the compound: crystal, solution). By the example of phosphorylation of bis[2-(4-tert-butyl)phen]ethylphosphine sulfide acetylene in the KOH-DMSO system it is shown that the reaction proceeds by double addition with the participation of phosphorus-centered nucleophiles.     

Multilayered iron complexes of metacyclophanes. 1H NMR behavior

Syntheses are described for a series of (η⁶-cyclophane)(η⁵cyclopentadienyl)iron(II) complexes, where the cyclophane moiety is anti-[2.2]metacyclophane, anti-4,12-dimethyl[2.2]metacyclophane, anti-4,12-dimethyl-7,15-dimethoxy[2.2]metacyclophane, and [2.2](2,5)thiophenophane. The triple-layered complexes η⁶,η⁶-anti-[2.2]metacyclophane)bis[(η⁵-cyclopentadienyl)iron(II)] bis(hexafluorophosphate) and (η⁶,η⁶-anti-4,12-dimethyl[2.2]metacyclophane)bis[(η⁵-cyclopentadienyl)iron(II)] bis(hexafluorophosphate) were also prepared. The NMR spectra of these compounds provide a useful insight into the nature of the iron-cyclophane bonding.     

Reactions with 5-aminopyrazoles. I. Synthesis of halogen-containing fused pyrazoles

5-Amino-3-phenylpyrazole (I) and 5-amino-4-bromo-3-phenylpyrazole (II) reacted with ethyl acetoacetate and acetylacetone to give various pyrazolo[1,5-a]pyrimidines IV-VI and with benzoins to give different fused pyrazoles, namely, imidazo[1,2-b]pyrazoles IX, pyrrolo[2,3-c]pyrazoles X and pyrazolo[4,3-b][1,4]oxazines XII. Diazotized II was coupled with active methylene-containing nitriles to afford pyrazolo[5,1-c]-as-triazines XIV.     

Potentiometric, electronic structural, and ground- and excited-state optical properties of conjugated bis[(porphinato)zinc(II)] compounds featuring proquinoidal spacer units

We report the synthesis, optical, electrochemical, electronic structural, and transient optical properties of conjugated (porphinato)zinc(II)-spacer-(porphinato)zinc(II) (PZn-Sp-PZn) complexes that possess intervening conjugated Sp structures having varying degrees of proquinoidal character. These supermolecular PZn-Sp-PZn compounds feature Sp moieties {(4,7-diethynylbenzo[c][1,2,5]thiadiazole (E-BTD-E), 6,13-diethynylpentacene (E-PC-E), 4,9-diethynyl-6,7-dimethyl[1,2,5]thiadiazolo[3,4-g]quinoxaline (E-TDQ-E), and 4,8-diethynylbenzo[1,2-c:4,5-c']bis([1,2,5]thiadiazole) (E-BBTD-E)} that regulate frontier orbital energy levels and progressively increase the extent of the quinoidal resonance contribution to the ground and electronically excited states, augmenting the magnitude of electronic communication between terminal (5,-10,20-di(aryl)porphinato)zinc(II) units, relative to that evinced for a bis[(5,5',-10,20-di(aryl)porphinato)zinc(II)]butadiyne benchmark (PZnE-EPZn). Electronic absorption spectra show significant red-shifts of the respective PZn-Sp-PZn x-polarized Q state (S0 --> S1) transition manifold maxima (240-4810 cm(-1)) relative to that observed for PZnE-EPZn. Likewise, the potentiometrically determined PZn-Sp-PZn HOMO-LUMO gaps (E1/2(0/+) - E1/2(-/0)) display correspondingly diminished energy separations that range from 1.88 to 1.11 eV relative to that determined for PZnE-EPZn (2.01 eV). Electronic structure calculations provide insight into the origin of the observed PZn-Sp-PZn electronic and optical properties. Pump-probe transient spectral data for these PZn-Sp-PZn supermolecules demonstrate that the S1 --> S(n) transition manifolds of these species span an unusually broad spectral domain of the NIR. Notably, the absorption maxima of these S1 --> S(n) manifolds can be tuned over a 1000-1600 nm spectral region, giving rise to intense excited-state transitions approximately 4000 cm(-1) lower in energy than that observed for the analogous excited-state absorption maximum of the PZnE-EPZn benchmark; these data highlight the unusually large quinoidal resonance contribution to the low-lying electronically excited singlet states of these PZn-Sp-PZn species. The fact that the length scales of the PZn-Sp-PZn species (approximately 25 angstrom) are small with respect to those of classic conducting polymers, yet possess NIR S1 --> S(n) manifold absorptions lower in energy, underscore the unusual electrooptic properties of these conjugated structures.     

Proton nuclear magnetic resonance and infra-red studies of the outer-sphere hydration of pentane-2,4-dionato metal complexes in benzene solution

Studies of hydrogen bonding between water and bis(pentane-2,4-dionato)-beryllium(II) (Be(acac)₂), bis(3-methylpentane-2,4-dionato)-beryllium(II) (Be(Meacac)₂), and tris(pentane-2,4-dionato)cobalt(III) (Co(acac)₃) have been undertaken in [²H]₆-benzene solution using¹H NMR and infra-red spectroscopy. Equilibrium constants for 1:1 water-metal complex hydrates, and approximate enthalpies and entropies of reaction, have been measured from the¹H NMR data. The equilibrium constants are larger for Co(acac)₃ than for the Be(II) complexes, in line with previous data for the partition of these chelates between water and aliphatic hydrocarbon solvents.     

Heteroaromatic boron compounds. XV. Deuteriodeprotonation in some borazarothienopyridines and thienopyridines

Deuteriodeprotonation of some substituted 4,5-borazarothieno[2,3-c]pyridines (I) and 7,6-borazarothieno[3,2-c]pyridines (II) has been studied by the nmr technique. Exchange occurred predominantly in the 3-position, and the effect of methyl substitution on rate is discussed. The rates of exchange in some derivatives of I and II were compared with those of the isoelectronic thieno[2,3-c]pyridines (III) and thieno[3,2-c]pyridines (IV). Similar rates were obtained, confirming the aromatic nature of I and II. The deuteriodeprotonation of 4-methyl-4,5-borazaro-thieno[2,3-c]pyridine (Ie), 7-methyl-7,6-borazarothieno[3,2-c]pyridine (IIe), 4-methylthieno-[2,3-c]pyridine (IIIe), and 7-methylthieno[3,2-c]pyridine (IVe) were measured at different concentrations of deuteriosulfuric acid and different temperatures, showing that the protonated heterocycles are substrates in the deuteriodeprotonation reaction. Standard rates at p0 H and 100° were calculated for these systems.     

13C NMR spectra of 1,4,5,8-tetraazaphenanthrene derivatives

The ¹³C NMR spectra of 1,4,5,8-tetraazaphenanthrene (pyrazino[2,3-f] quinoxaline), eleven of its derivatives [2- and 3-chloro, -methoxy and -(1′-piperidino), 2,3-dichloro, -dimethoxy, -dimethyl and -di(1′-piperidino) and 9-methoxy] and of 1,4,5,8,9,12-hexaazatriphenylene (dipyrazino[2,3-f: 2′,3′-h]quinoxaline) have been assigned by {¹H} selective decoupling experiments, correlations and additivities of substituent-induced chemical shifts and proton–carbon coupling patterns. Assignments of proton spectra are extended.     

1-Ethoxycarbonyl-3-ferrocenyl-propan-1,3-dion und Ferrocen-1,1'bis(2,4-dioxobutansäureethylester) als Liganden für Übergangsmetallionen. Kristallstruktur von Bis(1-ethoxycarbonyl-3-ferrocenyl-propan-1,3dionato)kupfer(II)

1-Ethoxycarbonyl-3-ferrocenyl-propane-1,3-dion and Ferrocene-1,1′bis(2,4-dioxobutanoic acid ethylester) as Ligands for Transition Metal Ions. Crystal Structure of Bis(1-ethoxycarbonyl-3-ferrocenyl-propane-1,3dionato)copper(II) The ligands 1-ethoxycarbonyl-3-ferrocenyl-propane-1,3-dion and ferrocene-1,1′-bis(2,4-dioxo-butanoic acid ethylester) have been prepared by reaction of acetylferrocene or 1,1′-diacetylferrocene and diethyl oxalate. They yield neutral chelates with Cu^II, Ni^II, Zn^II, Co^II, and Mn^II. The acid dissociation constants of the ligands and the stability constants of their metal complexes including Fe^II complexes are reported. The structure of bis(1-ethoxycarbonyl-3-ferrocenyl-propane-1,3-dionato)copper(II) was determined by X-ray structure analysis. A cis arrangement with a nearly square planar coordination sphere at the Cu atom is found.     

Polymeric copper(II) and nickel(II) complexes of a tetraoxime containing a binucleating macrocycle ligand

Polymeric copper(II) and nickel(II) complexes of a binucleating tetraoxime macrocycle, 6,6-methylene-bis[1,12-di(hydroximino)- 2,3;9,10-dibenzo-1,11-diaza-4,8-dithiacyclotridecane] (H4L), have been prepared and characterised by elemental analysis, magnetic moments, i.r., uv/vis., and e.p.r. spectral studies. I.r. spectra show that the ligand acts in a tetradentate manner and coordinates via N, S and O donor atoms. The geometry of the resulting metal chelates is discussed with the help of magnetic and spectroscopic measurements. The elemental analyses, stoichiometry and the spectroscopic data of the complexes indicate that the copper(II) and nickel(II) ions are coordinated by the coordination environment of the ligand. The spectral data suggest a distorted tetragonal geometry for polymeric copper(II), and nickel(II) ions in the complexes. The stoichiometry of the metal-to- H4L ratio of complexes (2) and (3), prepared from CuCl2 and NiCl2 respectively, was 3:1, suggesting the formation of polymeric species.     

Synthesis of novel chiral tetraaza ligands and their application in enantioselective transfer hydrogenation of ketones

Novel chiral tetraaza ligands(R)-N,N′-bis[2-(piperidin-1-yl)benzylidene]propane-l,2-diamine 6 and(S)-N-[2-(piperidin-l- yl)benzylidene]-3-{[2-(piperidin-1-yl)benzylidene]amino}-alanine sodium salt 7 have been synthesized and fully characterized by NMR,IR,MS and CD spectra.The catalytic property of the ligands was investigated in Ir-catalyzed enantioselective transfer hydrogenation of ketones.The corresponding optical active alcohols were obtained with high yields and moderate ees under mild reaction conditions.     

Synthesis,crystal structures and characterizations of three new copper(II) complexes including anti‐inflammatory diclofenac

Three new diclofenac‐based copper(II) complexes, namely tetrakis{μ‐2‐[2‐(2,6‐dichloroanilino)phenyl]acetato‐κ²O:O′}bis(methanol‐κO)copper(II), [Cu₂(μ‐dicl)₄(CH₃OH)₂] ( 1 ), bis{2‐[2‐(2,6‐dichloroanilino)phenyl]acetato‐κ²O,O′}bis(1‐vinyl‐1H‐imidazole‐κN³)copper(II), [Cu(dicl)₂(vim)₂] ( 2 ), and bis{2‐[2‐(2,6‐dichloroanilino)phenyl]acetato‐κ²O,O′}bis(1H‐imidazole‐κN³)copper(II), [Cu(dicl)₂(im)₂] ( 3 ) [dicl is diclofenac (C₁₄H₁₀Cl₂NO₂), vim is 1‐vinylimidazole (C₅H₆N₂) and im is imidazole (C₃H₄N₂)], have been synthesized and characterized by elemental analysis, FT–IR spectroscopy, thermal analysis and single‐crystal X‐ray diffraction. X‐ray diffraction analysis shows that complex 1 consists of dimeric units in which the dicl ligand exhibits a bidentate syn,syn‐μ₂ coordination mode linking two copper(II) centres. Complexes 2 and 3 have mononuclear units with the general formula [Cu(dicl)₂L₂] (L is vim or im) in which the Cu^II ions are octahedrally coordinated by two L and two dicl chelating ligands. The L and dicl ligands both occupy the trans positions of the coordination octahedron. The different coordination modes of dicl in the title complexes were revealed by Fourier transform IR (FT–IR) spectroscopy. The spin matching between the copper(II) centres in the dimeric [Cu₂(μ‐dicl)₄(CH₃OH)₂] units was also confirmed by magnetic data to be lower than the spin‐only value and electron paramagnetic resonance (EPR) spectra. The thermal properties of the complexes were investigated by thermogravimetric (TG) and differential thermal analysis (DTA) techniques.     

Azinotriazines. II Cyclizations leading to pyrido[3,4-e] - and [4,3-e]-as-triazines. Ring interconversion of a pyrido-as-triazine 1-oxide to a pyridotriazole

Treatment of 4-chloro-3-nitropyridine (I) with hydrazine hydrate followed by catalytic reduction gave 3-amino-4-hydrazinopyridine (III). Acid-catalyzed cyclizations of III and subsequent dehydrogenation gave pyrido[3,4-e]-as-triazines (V). Treatment of I with guanidine followed by base-catalyzed cyclization gave 3-aminopyrido[4,3-e]-as-triazine 1-oxide (VII). The 1-oxide function was removed by reduction and subsequent dehydrogenation gave the 3-amino derivative (IX). On treatment with hot alkali VII rearranged to a triazolo[4,5-c]pyridine (X). The ultraviolet and nmr spectra of derivatives of the title ring systems are reported.     

Discotic metallomesogens: Synthesis and properties of square planar metal bis(β-diketonate) complexes

Discotic β-diketonate liquid crystals containing palladium(II), and oxovanadium(IV), (V≡0), analogous to known copper complexes (which display discotic lamellar and columnar mesophases), have been prepared and characterized. These are the first enantiotropic discotics containing Pd(II) and among the earliest examples containing VO(IV). The best-behaved Pd(II) complex is [Pd(DK 10, 10)₂], and it also is probable that the complexes [Pd(DKn,n)₂] (n = 7-9) are mesomorphic, however their characterization is difficult due to decomposition in the isotropic phase. The mesophase of [Pd(DK 10²,10²)₂], which appears below 100°C, is suggested to be an example of the rare N_d phase on the basis of optical microscopy. The complex [VO(DK8,8)₂] is an enantiotropic discotic vanadyl complex; the monotropic behaviour of [VO(DK 10,10)₂] was also confirmed. It is suggested that the discotic phase which occurs for [VO(DK 8,8)₂] is more organized than that of [Cu(DK 8,8)₂].     

Relation between intramolecular NH...S hydrogen bonds and coordination number in mercury(II) complexes with carbamoylbenzenethiol derivatives

A novel series of bis(carbamoylthiophenolato)mercury(II) complexes, [Hg(S-RNHCOC6H4)2] (1, R = 2-t-Bu; 2, R = 2-CH3; 3, R = 2-C6H5CH2; 4, R = 4-t-Bu), and a tetrakis(carbamoylthiophenolato)mercury(II) complex, (NEt4)2[Hg-(S-2-CH3NHCOC6H4)4] (5), were synthesized and characterized by 1H NMR, IR, 199Hg NMR, and crystallographic analyses. The bis(carbamoylthiophenolato)mercury complexes 1-3 do not have intramolecular NH...S hydrogen bonds between the amide NH group and the sulfur atom coordinated to mercury, whereas the tetrakis(thiophenolato)mercury complex 5 does have an intramolecular NH...S hydrogen bond. A relatively weak NH...S hydrogen bond in 5 can be seen in the 1H NMR spectra and the IR spectra in chloroform and in the solid state. The 199Hg NMR spectra in bis(carbamoylthiophenolato)mercury complexes 1-4 show a downfield shift, with an increase in the flow of electrons to mercury(II) from the oxygen atom due to the intramolecular Hg...O bonding interaction. Conversely, the 199Hg NMR spectra in 5 show a high-field shift with a decrease in the flow of electrons to mercury(II) from the sulfur atom due to the intramolecular NH...S hydrogen bond.     

[La2I2(OH)2(Dibenzo-18-Krone-6)2]I(I3), ein kationischer,dimerer in-cavity-Komplex mit Iodid und Triiodid als Anionen

[La₂I₂(OH)₂(dibenzo-18-crown-6)₂]I(I₃), a Cationic Dimeric in-cavity Complex with Iodide and Triiodide as Anions Single crystals of [La₂I₂(OH)₂(dibenzo-18-crown-6)₂]I(I₃) are obtained from the reaction of LaI₃ and dibenzo-18-crown-6 in acetonitrile. The crystal structure monoclinic, C2/m, Z = 4, T = 293 [100] K, a = 2179(3) [2162.3(3)], b = 1070.3(3) [1069.6(1)], c = 1118.2(3) [1110.6(1)] pm, β = 93.1(1) [92.83(1)]°, R1 = 0.0601 [0.0411], wR2 = 0.1449 [0.1014] contains hydroxide-bridged cationic dimers and iodide as well as triiodide as anions.