Ligand exchange in the complexone-porphyrin macrocycle system in reactions of copper(II) ethylenediaminetetraacetate with porphyrins and phthalocyanines

Complexation between 5,10,15,20-tetraphenylporphine H₂TPP and tetra(tert-butyl)phthalocyanine H₂(t-Bu)₄Pc with copper(II) ethylenediaminetetraacetate in DMSO was studied by spectrophotometry. The kinetic parameters of the reaction were calculated and the mechanism of ligand exchange in the complexone-porphyrin macrocycle system was proposed. The reactivities of H₂TPP and H₂(t-Bu)₄Pc in reactions with copper ethylenediaminetetraacetate and some other copper chelate complexes were compared.     

Spectral properties and solubility of the lanthanide complexes with substituted and annelated porphyrazines

An analysis of the electronic optical properties and solubility in chloroform and DMF of the erbium and ytterbium complexes with porphyrazine and its octaphenyl- and octa(p-alkylsulfamoylphenyl)-substituted derivatives and tetrapyrazinoporphyrazine and its octaethyl-, tetra(tert-butyl)-, and octaphenyl-substituted derivatives is presented. The dependence of the electronic optical properties and solubility on the composition of the macrocycle of the studied complexes, namely, on the nature of the extraligand and peripheral environment of the porphyrazine macrocycle, is shown.     

Kinetics of the formation and dissociation of complexes of cobalt(II) with <Emphasis Type="Italic">meso</Emphasis>-Phenylocta(methyl)porphyrin derivatives in organic solvents

The influence of the deformation of the tetrapyrrole aromatic macrocycle and the electronic effects of substituents on the kinetic parameters in the formation and dissociation reactions of cobalt complexes of porphyrins are discussed on the basis of a study of the kinetics of the formation and dissociation of cobalt complexes with meso-phenyl octa(methyl)porphyrin derivatives: 5,10,15-triphehyl octa(methyl) porphyrin; 5,15-bis-(3′,5′-di-tert-butyl phenyl) octa(methyl)porphyrin; 5,10,15-tris-(3′,5′-di-tert-butyl phenyl) octa(methyl)porphyrin; and 5,10,15,20-tetrakis-(3′,5′-di-tert-butyl phenyl) octa(methyl)porphyrin in acetic acid and pyridine.     

Synthesis,Structure, and Spectroscopic Properties of Octa(iso‐pentoxy)phthalocyaninatometal Complexes

A series of octa‐substituted metal phthalocyanines [MPc(OC₅H₁₁)₈] (M = Co, Ni, Cu, Zn, Pc = phthalocyaninato, (OC₅H₁₁)₈ = iso‐pentoxy) were obtained from condensation of iso‐pentoxy phthalonitrile in the presence of DBU in n‐pentanol. The compounds were characterized using elemental analysis, IR, and UV/Vis spectra. The crystal structures of all compounds except M = Zn were determined by X‐ray diffraction methods. It was found that the distortion of Pc skeleton come of not only the intra‐molecular steric congestion of bulky substituents, but also the slipped overlaps of the closest molecules. The relations of some bond lengths of the Pc's skeleton to the substituents and central metal atom, as well as the spectroscopic properties are discussed.     

X-ray crystal structure of the tetra(tert-butyl)erbate anion and attempts to prepare tetravalent organolanthanide complexes

The new [Li(DME)₃⁺] salt of the previously-known tetra(tert-butyl)erbate(III) anion [Er(t-Bu)₄⁻] has been prepared and structurally characterized. The erbium(III) center is ligated by four tert-butyl groups in an approximately tetrahedral arrangement. The C–Er–C angles between the tert-butyl groups range from 108.8(3)° to 111.2(3)° and the Er–C distances range from 2.352(6) to 2.395(6) Å. The lithium cation is surrounded by three DME molecules, which form a distorted octahedral coordination sphere. Attempts to oxidize the analogous terbate complex [Li(DME)₃][Tb(t-Bu)₄] and its cerium analog to electrically neutral tetra(alkyl)lanthanide(IV) compounds are described.     

Cage octaphenylsilsesquioxane from cyclic tetrasiloxanetetraol and its sodium salt

Cage octasilsesquioxane with various substituents were obtained by the condensation reaction of various all-cis cyclic tetrasiloxanetetraol (R-T₄-tetraol, R = phenyl, p-tolyl, i-butyl, naphthyl) with benzyltrimethylammonium hydroxide or tetrabutylammonium fluoride as a catalyst. Co-condensation of phenyl-T₄-tetraol with phenyl-d₅-T₄-tetraol or with p-tolyl-T₄-tetraol were found to proceed through reshuffling process evidenced by scrambling of the substituents. Pure octa(4-bromo-substituted phenyl)octasilsesquioxane was synthesized for the first time from tetra(4-bromo-substituted phenyl)tetrasiloxanetetraol sodium salt.     

Kinetics of the Acid-Base Interaction between Tetra(4-<Emphasis Type="Italic">tert</Emphasis>-butyl)phthalocyanine and Nitrogen-Containing Bases in Dimethyl Sulfoxide

Specific features of the acid-base interaction of tetra(4-tert-butyl)phthalocyanine with cyclic and acyclic nitrogen-containing bases in dimethyl sulfoxide are studied. The effect of pK _a of proton-withdrawing molecules, basicity of a medium, and steric screening of acidic NH centers on the kinetic parameters of formation of proton-transfer complexes stable in time is shown.     

Synthesis of pyridine-containing α-hydrazino phosphonates by two-component catalytic procedure

Pyridine-containing α-hydrazino phosphonates were synthesized in high yields by reaction of hydrazones of pyridine series with diethyl phosphite in the presence of [tetra(tert-butyl)-phthalocyanine]aluminum chloride as a catalyst.     

Structural evidence of the formation of ZnPc-DBU complex during recrystallisation of commercially available ZnPc dye

Recrystallisation of commercially available ZnPc dye in a liquid 2-cyanopyridine or 4-cyanopyridine leads to formation of well developed parallelepipedal violet single crystals with the same composition in both cases. A combination of X-ray single crystal analysis and NMR spectroscopy together with an elemental analysis enable to identify the composition and the structure of the obtained ZnPc-DBU crystals (where DBU is 1,8-diazabicyclo[4.5.0]undec-7-ene). The commercially available ZnPc dye contains DBU as impurity, since DBU is usually used as a strong base in the synthesis of phthalocyanines, and therefore recrystallisation in 2- or 4-cyanopyridine as weaker bases leads to formation of ZnPc-DBU crystals. The ZnPc-DBU crystallizes in the centrosymmetric space group P2₁/c of the monoclinic system with four molecules per unit cell. The Zn center is equatorially coordinated by four isoindole N atom of phthalocyaninato macrocycle and by the N atom of DBU ligand in an axial position. Thus the ZnPc unit of the ZnPc-DBU molecule adopts a saucer shape form. The ZnPc-DBU compound exhibits better solubility than the parent ZnPc compound due to the steric hindrance of the axial DBU ligand that lowers the aggregation in solution. The electronic spectra in DBU and cyclohexane solutions exhibit the B and Q bands typical of the phthalocyaninate(2-) macrocycle. The bands are blue shifted in cyclohexane solution in relation to DBU solution.     

XYZH systems as potential 1,3-dipoles. Part 62: 1,3-Dipolar cycloaddition reactions of metallo-azomethine ylides derived from α-iminophosphonates

Metallo-azomethine ylides, generated from iminophosphonates in combination with LiBr or AgOAc and bases Et₃N, DBU, t-butyl tetramethylguanidine(BTMG) undergo cycloaddition to give dialkyl pyrrolidine-2-phosphonates along with the corresponding Michael adduct in some cases. Cycloadditions with the chiral dipolarophile 5R-(1′R,2′S,5′R-menthyloxy)-2-(5H)-furanone (MOF) afforded enantiopure cycloadducts.     

Determination of acidity of di-, tri-, and tetraazaporphyrins in dimethyl sulfoxide-potassium cryptate medium

Acidic properties of 10,20-diaza-3,7,13,17-tetramethyl-2,8,12,18-tetra-n-hexylporphyrin, 2,7,12,17-tetra-t-butyltetrabenzo-5,10,15-triazaporphyrin and octa(n-amyloxy)phthalocyanine in the system of dimethyl sulfoxide-potassium cryptates (DMSO-K[222]OH) at ambient temperature was investigated by the method of spectrophotometric titration. The porphyrins in the DMSO-K[222]OH medium were shown to dissociate sequentially forming mono- and dianions in two steps. The concentration ranges of existence of the anionic forms and the acidity sequence of the studied meso-aza-substituted porphyrins were investigated.     

The effects of substituents,molecular symmetry,ionic radius of the rare earth metal,and macrocycle on the electronic absorption spectra characteristics of sandwich-type bis(phthalocyaninato) and mixed (phthalocyaninato)(porphyrinato) rare earth complexes

The electronic absorption spectroscopic data for two series of 60 unsubstituted/substituted bis(phthalocyaninato) and mixed [tetrakis(4-chlorophenyl)porphyrinato](phthalocyaninato) rare earth complexes M(Pc)₂, M(Pc^∗)₂ and M(TClPP)(Pc) [M = Y, La…Lu except Pm; Pc^∗ = dianion of 2,3,9,10,16,17,23,24-octakis(4-methoxyphenoxy)phthalocyanine [Pc(MeOPhO)₈], dianion of 3(4),12(13),21(22),30(31)-tetra(tert-butyl)phthalocyanine (TBPc) and TClPP = tetra(4-chloro)phenylporphyrin] have been measured in CHCl₃. In this paper, the influence of the symmetry of macrocycle rare earth molecules, the effects of ionic radius of the rare earth metal and the influence of substituent species (tert-butyl and 4-methoxyphenoxy groups) onto the peripheral benzene rings on the electronic absorption characteristics of sandwich-type compounds have also been tentatively studied in detail.     

Kinetic characteristics of the destruction of β,β-annelated porphyrazines in a nitrogen-containing base–dimethylsulfoxide system

The state of tetra(1,2,5-thiadiazolo)porphyrazine in a dimethyl sulfoxide medium is investigated. Relatively high stability is observed for the resulting proton-transfer complex, and a chemical structure is proposed for it. It is shown that the nature of the substituent in the porphyrazine macrocycle influences the kinetic parameters of the destruction of tetra(1,2,5-thiadiazolo)porphyrazine, tetra(5-tert-butylpyrazino) porphyrazine, octaethyltetrapyrazinoporphyrazine, and octaphenyltetrapyrazinoporphyrazine in a nitrogen-containing base–dimethylsulfoxide system. The effect the NH acidity of the porphyrazine macrocycle and the nature of the nitrogenous bases have on the reaction rate and activation parameters of the destruction of β,β-annelated porphyrazine proton-transfer complexes is established.     

Synthesis of a C3-symmetric macrocycle with alternating sugar amino acid and tyrosine residues

A C₃-symmetric macrocycle with alternating sugar amino acid and tyrosine residues was synthesized in seven steps from tyrosine tert-butyl ester and a sugar amino acid precursor derived from D-glucosamine. An Fmoc-protected D-glucosamine derivative was oxidized at C-6 to give the sugar amino acid, which was immediately coupled to tyrosine tert-butyl ester to produce an orthogonally protected building block. This building block was subsequently elongated to the trimer via the dimer, and finally cyclized to give the C₃-symmetric macrocycle.     

Porphyrin acidity and metal ion coordination revisited: electronic substitution effects

Macrocycle acidity and Zn²⁺ ion coordination are reported for three porphyrin derivatives which differ in both steric and electronic substitution effects on the macrocycle π-conjugated system. The role of the electronic substitution effects in the macrocycle deprotonation and metal ion chelating was found to be dominating whereas the macrocycle nonplanar distortions contribute to the acidity and metal chelation rate of the studied porphyrins in less extent. The contributions of both resonance and inductive electronic substitution effects have been distinguished based on the relationship between the weighted sum of resonance and inductive Hammett constants and the acidity and metal ion chelation rate.     

Acid-Base Properties of Octaaryltetraazaporphyrins

Stability constants were determined for acid forms of octa(4-chloromethylphenyl)-, octa(4-bromophenyl)-, and octa(4-nitrophenyl)tetraazaporphyrins, formed by acid-base interactions in H₂SO₄-CH₃COOH mixtures. The probability of formation of each form depends not only on the electronic structure of the molecule, but also on the composition and properties of the medium.     

Facile preparation of cyclopropanes from 2-iodoethyl-substituted olefins and 1,3-dihalopropanes with zinc powder

Two efficient, simple, cheap, and environmentally benign preparations of cyclopropanes were achieved. One is the formation via 3-exo-trig manner from various electron-deficient 2-iodoethyl-substituted olefins with zinc powder in a mixture of t-butyl alcohol and water, and the other is the formation via 3-exo-tet manner from various 1,3-dihalopropanes with zinc powder in ethanol.     

Stereoselective synthesis of a new methyl-substituted inositol derivative

The stereoselective synthesis of methyl-substituted inositol derivative is described. Diene diacetate which is a key compound was first prepared via three steps starting from 2-methyl-p-benzoquinone. Osmium-catalyzed regio- and stereoselective dihydroxylation of diene diacetate afforded cis-diol diasetate, which then produced tetra acetate via acetylation with Ac₂O-pyridine. Oxidation and acetylation of the other alkene moiety in the compound gave a hexaacetate compound stereoselectively. Finally, the acetate groups were removed by NH₃ leading to formation of the desired new methyl-substituted inositol derivative having a muco-inositol-type stereochemical pattern in the six-membered ring. Spectroscopic methods were used for characterization of all synthesized compounds.     

Complex formation of tetra(3,5-di-<Emphasis Type="Italic">tert</Emphasis>-butylphenyl)porphine with copper(II) and zinc(II) acetates in organic solvents

The effect of accumulation of the tert-butyl groups in the phenyl rings of tetraphenylporphine on the complex formation rate of tetra(3,5-di-tert-butylphenyl)porphine (I) with copper(II), zinc(II), and cadmium(II) acetates in acetic acid and in a mixed ethanol-benzene solvent was studied by the chemical kinetics method with spectrophotometric monitoring. The activation characteristics of the complex formation were calculated. The complex with zinc was found to form three times more slowly that the copper complex. Benzene additives to the organic solvent decreased the reaction rate because of steric hindrance created by the benzene molecules that formed stable solvates with compound I.     

Unerwartete Reduktion von [Cp*TaCl4(PH2R)] (R = But,Cy, Ad,Ph, 2,4,6‐Me3C6H2; Cp* = C5Me5) durch Reaktion mit DBU – Molekülstruktur von [(DBU)H][Cp*TaCl4] (DBU = 1,8‐Diazabicyclo[5.4.0]undec‐7‐en)

Unexpected Reduction of [Cp*TaCl₄(PH₂R)] (R = Bu^t, Cy, Ad, Ph, 2,4,6‐Me₃C₆H₂; Cp* = C₅Me₅) by Reaction with DBU – Molecular Structure of [(DBU)H][Cp*TaCl₄] (DBU = 1,8‐diazabicyclo[5.4.0]undec‐7‐ene) [Cp*TaCl₄(PH₂R)] (R = Bu^t, Cy, Ad, Ph, 2,4,6‐Me₃C₆H₂ (Mes); Cp* = C₅Me₅) react with DBU in an internal redox reaction with formation of [(DBU)H][Cp*TaCl₄] ( 1 ) (DBU = 1,8‐diazabicyclo[5.4.0]undec‐7‐ene) and the corresponding diphosphane (P₂H₂R₂) or decomposition products thereof. 1 was characterised spectroscopically and by crystal structure determination. In the solid state, hydrogen bonding between the (DBU)H cation and one chloro ligand of the anion is observed.