Desolvaton of Zinc(II)tetra-tert-butylphthalocyanine Crystal Solvates as Probed by Thermogravimetry

Kinetic analysis of the thermal destruction of complexes of zinc(II)tetra-tert-butylphthalocyanine Zn(t-Bu)₄Pc with organic solvent molecules has been carried out. For ligands having high ionization potentials, long refluxing of solution is required for preparing biligand complexes. For molecular ligands whose ionization potentials do not exceed 9.2 eV, the composition of complexes with Zn(t-Bu)₄Pc is independent of the preparation parameters. The destruction of the Zn(t-Bu)₄Pc complexes with n-propylamine, diethylaniline, piperidine (1: 1, cold synthesis), diethylamine, morpholine, quinoline, or cyclopentanone (1: 2, hot synthesis; 1: 2, cold synthesis) obeys fist-order equations; for complexes with pyridine, 1,4-dioxane, DMF, cyclopentanone (1: 1, hot synthesis), 3-dimethylaminopropionitrile, or piperidine (1: 2, hot synthesis), destruction obeys second-order equations. The activation energies of thermal destruction for the first group of molecular complexes fall in the range from 89 to 370 kJ/mol; the rate-controlling stage is nucleation and growth. For the second group, the activation energies fall in the range from 160 to 640 kJ/mol; the rate-controlling stage is a chemical reaction.     

Dimerization and Coordination Properties of Zinc(II)tetra-4-alkoxybenzoyloxiphthalocyanine in Relation to DABCO in <Emphasis Type="Italic">o</Emphasis>-Xylene and Chloroform

For the first time the interactions between zinc(II)tetra-4-alkoxybenzoyloxiphthalocyanine (Zn(4—O—CO—C₆H₄—OC₁₁H₂₃)Pc) and 1,4-diazabicyclo[2.2.2]octane (DABCO) in o-xylene and chloroform have been studied by calorimetric titration and NMR and electron absorption spectroscopic methods. It has been found that in o-xylene at concentrations of Zn(4—O—CO—C₆H₄—OC₁₁H₂₃)Pc higher than 6×10⁻⁴ mol⋅L⁻¹ π–π dimers species are formed (λ _max= 685 nm). Additions of DABCO to the solution up to mole ratio 1 : 8 (Zn(4—O—CO—C₆H₄—OC₁₁H₂₃)Pc : DABCO) lead to a shift of the aggregation equilibrium towards monomer species due to formation of monoligand axial complexes. Further increasing the DABCO concentration results in formation of Zn(4—O—CO—C₆H₄—OC₁₁H₂₃)Pc—DABCO—Zn(4—O—CO—C₆H₄—OC₁₁H₂₃)Pc sandwich dimers (λ _max= 675 nm).     

Crystal solvates of carboxy-substituted Zn(II) phthalocyaninates with pyridine

Physicochemical characteristics (composition, energetic and chemical stability) of the molecular complexes of carboxy-substituted Zn(II) phthalocyaninates with pyridine were determined. It was found that the carboxyl substituents in positions 4 and 5 of the complex Zn(4,5-COOH)₈Pc favor the formation of the most stable molecular complexes with pyridine. The carboxyl substituents in the composition of Zn(3-COOH)₄Pc are not solvated with pyridine due to steric hindrances and the formation of the hydrogen bond between the carboxyl H atom and the meso-nitrogen atom; the molecular complexes of a tetrasubstituted Zn(4-COOH)₄Pc with pyridine are unstable.     

X-ray diffraction and IR spectral characteristics of zinc(II)tetra-tert-butylphthalocyanine

According to well-known procedures, alpha- and beta-crystal polymorphic modifications of zinc(II)tetra-tert-butylphthalocianine (Zn(t-Bu)4Pc) were prepared and X-ray analysis of their powders was carried out. It was found that four tert-butyl groups in Zn(t-Bu)4Pc molecule do not prevent the formation of the alpha- and beta-polymorphs. The alpha- and beta-polymorphs differ from each other mainly by a mutual arrangement of neighboring metallophthalocyenine molecules in pi-stacking. Comparison of IR spectra of the alpha- and beta-polymorphs of ZnPc and Zn(t-Bu)4Pc was carried out. It was indicated that new bands appear at 670-690, 1256 and 1362 cm(-1) in the spectrum of Zn(t-Bu)4Pc in comparison with that of ZnPc. The appearance of new band at 1256 cm(-1) is assigned to rocking C-CH(3) vibrations and the band at 1362 cm(-1) to symmetrical deformational C-H vibrations of methyl groups of the peripheral substitutes. The main spectral characteristics for identification of the polymorphic modifications of Zn(t-Bu)4Pc are listed.     

Zinc(II) (o-hydroxybenzaldoximates) Complexes with Mono- and Bidentate Ligands

New complexes:Zn(Hsalox)(ox), Zn(Hsalox)(NHPh), Zn(Hsalox)(Hsal) and Zn(Hsalox)₂(1,2-diMeim) have been synthesised as a result of a reaction of Zn(salox) and Zn(Hsalox)₂ (where: salox ^2–=OC₆H₄CHNO^2–, Hsalox ^–=OC₆H₄CHNOH^–) with 8-hydroxyquinoline (Hox), o-aminophenol (NH₂Ph), o-hydroxybenzoic acid (H₂Sal) and 1,2-dimethylimidazole (1,2-diMeim). Chemical, X-ray and thermal analyses of the complexes and their sinters have been carried out. Thermal decomposition pathways have been postulated for the complexes. The mixtures about not definite composition have been obtained as a result of a reaction of zinc(o-hydroxybenzaldoximates) with imidazole(Him) and 4-methylimidazole (4-MeHim). This revised version was published online in August 2006 with corrections to the Cover Date.     

Comparative study of beryllium,magnesium and zinc phthalocyanine complexes with 4-picoline

Three new Be(II), Mg(II) and Zn(II) phthalocyaninato(2-) complexes with 4-picoline (4-Mepy) in the crystalline form have been obtained by recrystallization of the respective M(II)Pc in 4-picoline under water-free conditions. BePc and ZnPc in 4-picoline solution form 4 + 1 coordinated complexes, while the 4-Mepy molecules biaxially ligate MgPc. The planar phthalocyaninato(2-) macroring of BePc and ZnPc upon mono-axial ligation by the 4-Mepy molecule adopts the saucer-shape form. The interaction of the central M(II) with the ligated 4-Mepy molecule leads to a deviation of the metal from the centre cavity by ∼0.31 Å and ∼0.35 Å in the Be and Zn phthalocyaninato complexes, respectively. In MgPc, the Pc ring upon biaxial ligation retains a planar configuration. The axial M(II)–N(4-Mepy) bond is longer than the four equatorial M(II)–N_iso bonds in Mg and Zn phthalocyaninato complexes, while in the Be complex the opposite relation between the axial and equatorial Be–N bonds is observed. Thermogravimetric analysis for all these compounds exhibits only one slope down, due to the loss of 4-Mepy molecules from the complexes, which transform finally into the respective M(II)Pc complexes in the β-form.     

Synthesis and structure of heteroleptic triple-decker neodymium,europium, holmium,erbium, and ytterbium crown phthalocyaninates

Two series of heteroleptic crown-substituted tris(phthalocyaninate) complexes (Pc)Ln[(15C5)₄Pc]Ln(Pc) and [(15C5)₄Pc]Ln[(15C5)₄Pc]Ln(Pc), where 15C5 is 15-crown-5, (Pc²⁻) is the phthalocyaninate dianion, Ln = Nd, Eu, Ho, Er, and Yb, were prepared by the reaction of tetra-15-crown-5-phthalocyanine H₂[(15C5)₄Pc] with the corresponding lanthanide acetylacetonates and lanthanum bis(phthalocyaninate) La(Pc)₂, which was used as a phthalocyaninate dianion donor. The composition and structure of the synthesized complexes were confirmed by MALDI TOF mass spectrometry, UV-Vis absorption spectroscopy, and ¹H NMR. Complete assignment of the proton resonance signals of the paramagnetic lanthanide complexes was based on analysis of lanthanide-induced shifts.     

Monoalkyl- and monoaryl-amidotitanium complexes

A series of new monoalkyl- and monoaryl-amido complexes, CpTiCl₂NHR (R = Et, i-Pr, t-Bu, Ph), has been synthesized and characterized. They were made in essentially quantitative yields by a very convenient reaction of CpTiCl₃ with Me₃SiNHR. The new complexes yield NMR and IR spectroscopic data for monoalkylamido complexes, such data being previously scarce. The compounds have very reactive amido hydrogen atoms, as is demonstrated by their thermal decomposition and their reaction with (Lewis) bases such as amines or organoalkali compounds. The products are the new bridged imido complexes, (CpTiCI)₂(μ-NR)₂.     

Preparation of metal Niacin complexes and characterization using spectroscopic and electrochemical techniques

Metal complexes of Niacin (3-pyridin carboxylic acid) were prepared in aqueous medium and characterized by different physico-chemical methods. On the basis of elemental analysis the empirical formula of the complexes have been proposed as [Fe(C₆H₄NO₂)]Cl₂, [Co(C₆H₄NO₂)]Cl, [Zn(C₆H₄NO₂)]Cl, [Cd(C₆H₄NO₂)]Cl and [Hg(C₆H₄NO₂)]Cl. IR spectral data indicate that the metal-ligand bonding occurs through nitrogen atom of aromatic ring and oxygen atom of COO⁻-group. UV-visible spectra show that Fe(III) and Co(II) complexes show d-d electronic transition in addition to π → π*, n → π* and n → σ* transitions. The Fe(II) and Co(II) complexes are paramagnetic. QSTG analysis data strongly support the absence of water molecules in the complexes, and the weight of the residue corresponds to the respective metal oxides. Cyclic voltammetric studies suggest that the redox properties of Zn(II), Cd(II) and Hg(II) in their complexes are modified compared to the uncoordinated metal ion. The CV data also indicate that the charge transfer processes are not reversible.     

Highly soluble tetra lauryl alcohol substituted phthalocyanines; synthesis,electrochemistry, spectroelectrochemistry

The tetra peripherally β-substituted 2(3),9(10),16(17),23(24)-tetrakis undecyloxy phthalocyanine derivatives, M{Pc[O-(CH₂)₁₁CH₃)]₄} Pc: Phthalocyanine, [M: Zn(II)(2), Ga(III)(3), and Ti(IV)(4)], have been synthesized and characterized using FT-IR, ¹H, and ¹³CNMR, MS (MALDI-TOF), UV–vis, atomic force microscopy, electro and spectroelectro chemical and elemental analysis. The new synthesized complexes are soluble in both polar solvents and nonpolar solvents, such as THF, DMF, CHCl₃, CH₂Cl_2, benzene, and even hexane. Electrochemical and spectroelectrochemical measurements give common metal-based and/or Pc ring-based redox processes which support the proposed structures of the complexes. While titanium phthalocyanine exhibits metal- and Pc ring-based reduction and/or oxidation couples, gallium and zinc phthalocyanines give only Pc ring-based electron transfer processes.     

Comparative studies of photophysical and electrochemical properties of sulfur-containing substituted metal-free and metallophthalocyanines

The synthesis, photophysical and electrochemical properties of soluble sulfur-containing 4-(methylthio) benzenethiol substituted, non-peripherally metal-free and metallo (Zn, Ga, Co, and Mn) phthalocyanine complexes (2–6) are reported for the first time. The new phthalocyanines have been characterized by FT-IR spectroscopy, ¹H-NMR, ¹³C-NMR, mass and UV–Vis spectroscopy techniques. Spectroscopic properties of these compounds were investigated in different solvents. Spectral and photophysical (fluorescence quantum yield) properties of metal free (2), zinc(II) (3), and gallium(III) phthalocyanines (4) were reported in different solvents toluene, tetrahydrofuran, and dimethyl sulfoxide. These results suggest that the solvents play role on the fluorescence quantum yields Φ _F of the synthesized complexes (2–4). The electrochemical studies exhibit that while complexes (3) and (4) give only Pc ring-based redox processes, complexes (5) and (6) give both metal and ring-based redox reactions due to the energy level of metal in the Pc core lie between the HOMO and the LUMO of the ring.     

Thermoanalytical behaviour of carbaryl and its copper(II) and zinc(II) complexes

Non-isothermal techniques, i.e. thermogravimetry (TG) and differential scanning calorimetry (DSC), have been applied to investigate the thermal behaviour of carbaryl (1-naphthyl-N-methylcarbamate = 1-Naph-N-Mecbm) and its complexes, M(1-Naph-N-Mecbm)₄X₂, where M = Cu, X = Cl, NO₃ and CH₃COO and M = Zn, X = Cl. Carbaryl and Zn(1-Naph-N-Mecbm)₄Cl₂ complex exhibit two-stage thermal decomposition while the copper(II) complexes exhibit three and four-stage decomposition in their TG curves. The nature of the metal ion has been found to play highly influential role on the nature of thermal decomposition products as well as energy of activation ‘E*’. The presence of different anions does not seem to alter the thermal decomposition patterns. The complexes display weak to medium intensity exothermic and endothermic DSC curves, while the free ligand exhibits two endothermic peaks. The kinetic and thermodynamic parameters namely, the energy of activation ‘E*’, the frequency factor ‘A’ and the entropy of activation ‘S*’ etc. have been rationalized in relation to the bonding aspect of the carbaryl ligand. The nature and chemical composition of the residues of the decomposition steps have been studied by elemental analysis and FTIR data.     

Structure of reaction products of hydrous and anhydrous zinc acetates with 1,10-phenanthroline

A reaction of aqueous zinc acetate with 1,10-phenanthroline produces the ionic complex [(Phen)₂Zn(OOCMe)](OOCMe) · 5H₂O. A similar reaction of “anhydrous zinc acetate” [Zn₇(μ₄-O)₂(μ-OOCMe)₁₀][η-OC(Me)OHNEt₃]₂ in benzene yields a precipitate, which is recrystallized from acetonitrile into trinuclear (Phen)₂Zn₃(μ-OOCMe)₆; and the reaction in acetonitrile yields mononuclear (Phen)Zn(OOCMe)₂ · MeCN. These complexes have been characterized by single-crystal X-ray diffraction.     

Divalent transition metal complexes of 3,5-pyrazoledicarboxylate

New divalent transition metal 3,5-pyrazoledicarboxylate hydrates of empirical formula Mpz(COO)₂(H₂O)₂, where M=Mn, Co, Ni, Cu, Zn and Cd (pz(COO)₂=3,5-pyrazoledicarboxylate), metal hydrazine complexes of the type Mpz(COO)₂N₂H₄ where M=Co, Zn or Cd and Mpz(COO)₂nN₂H₄·H₂O, where n=1 for M=Ni and n=0.5 for M=Cu have been prepared and characterized by physico-chemical methods. Electronic spectroscopic data suggest that Co and Ni complexes adopt an octahedral geometry. The IR spectra confirm the presence of unidentate carboxylate anion (Δν=ν_asy(COO^–)–ν_sym(COO^–)>215 cm^–1) in all the complexes and bidentate bridging hydrazine (ν_N–N=985–950 cm^–1) in the metal hydrazine complexes. Both metal carboxylate and metal hydrazine carboxylate complexes undergo endothermic dehydration and/or dehydrazination followed by exothermic decomposition of organic moiety to give the respective metal oxides as the end products except manganese pyrazoledicarboxylate hydrate, which leaves manganese carbonate. X-ray powder diffraction patterns reveal that the metal carboxylate hydrates are isomorphous as are those of metal hydrazine complexes of cobalt, zinc and cadmium.     

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.     

The syntheses and coordination properties of M(CO)3X(DAB) (M = Mn,Re; X = Cl,Br, I; DAB = 1,4-diazabutadiene)

M(CO)₅X (M = Mn, Re; X = Cl, Br, I) reacts with DAB (1,4-diazabutadiene = R₁N=C(R₂)C(R₂)′=NR′₁) to give M(CO)₃X(DAB). The ¹H, ¹³C NMR and IR spectra indicate that the facial isomer is formed exclusively. A comparison of the ¹³C NMR spectra of M(CO)₃X(DAB) (M = Mn, Re; X = Cl, Br, I; DAB = glyoxalbis-t-butylimine, glyoxyalbisisopropylimine) and the related M(CO)₄DAB complexes (M = Cr, Mo, W) with Fe(CO)₃DAB complexes shows that the charge density on the ligands is comparable in both types of d⁶ metal complexes but is slightly different in the Fe-d⁸ complexes. The effect of the DAB substituents on the carbonyl stretching frequencies is in agreement with the A′(cis) > A″ (cis) > A′(trans) band ordering.Mn(CO)₃Cl(t-BuNCHCHNt-Bu) reacts with AgBF₄ under a CO atmosphere yielding [Mn(CO)₄(t-BuNCHCHN-t-Bu)]BF₄. The cationic complex is isoelectronic with M(CO)₄(t-BuNCHCHNt-Bu) (M = Cr, Mo, W).     

The Suprising Variety of Products from Reactions of P-P Bonds with Dichlorogermylene

Abstract

Insertion of dichlorogermylene (from GcCl₂-dioxane) into the P-P bonds of tetraalkyldiphosphanes ((PRR)₂ (2a: R, R ? i-Pr; 2b: R? t-Bu, R?i-Pr; 2C; R, R, ?t-Bu) leads 10 dichlorobis(dialkylphosphanyl)germanes 3a-c. With 2a. the insertion remains incomplete: 38 exists in an equilibrium with an adduct of diphosphane 2a with GeCI₂, Subsequently 3b and 3c undergo a-climinarions to dialkylchlorophosphanes Sb and Sc and the dimeric phosphanylgermylenes (RR PGeGl)² 4b and 4c [1]. Similar to the above (but in absence of dioxane), reacting the richlorogcrmylphosphane i-Pr(t-Bu)PGeCL₃, 7c [2] with the related trichlorosilylphosphanc i-Pr(t-Bu)PSiCl₃ provided a mixture of SiCl₄, 1c, 3c, 5c and 7c, 3a and 3c have been trapped as inert molybdenum complexes (CO)₄ MO(μ-PRR)₂ GeGl₂ 6a and 6c from cquilibrilia conraining la/ 2a/ 3a and 3c/ 4c / 5c / 7c respectively.     

Complex Formation Equilibria Between Zinc(II), Nitrilo-tris(Methyl Phosphonic Acid) and Some Bio-relevant Ligands. The Kinetics and Mechanism for Zinc(II) Ion Promoted Hydrolysis of Glycine Methyl Ester

Binary and ternary complexes of zinc(II) involving nitrilo-tris(methyl phosphonic acid (H₆A) and amino acids, peptides (HL), or DNA constituents have been investigated. The stoichiometry and stability constants for the complexes formed are reported. The results show that ternary complexes are formed in a stepwise manner whereby nitrilo-tris(methylphosphonic acid) binds to zinc(II), which is then followed by coordination of an amino acid, peptide or DNA. Zinc(II) was found to form ZnA and ZnAH _n complex species where n=3, 2 or 1. The stabilities of the ternary complexes are compared with the stabilities of their corresponding binary complexes. The concentration distributions of the various complex species have been evaluated. The kinetics of the base hydrolysis of glycine methyl ester in the presence of Zn(II)-NTP complexes was studied in aqueous solution using a pH-stat technique. The pK _a for ionization of the coordinated water molecule is 9.14 as determined from the kinetic results, while direct potentiometric titration of the complex [Zn(NTP)(H₂O)] gave 9.98 (±0.02). The rate constant for the intramolecular attack of coordinated hydroxide on the ester is k=(2.65×10⁻⁴±0.003) dm³⋅mol⁻¹⋅s⁻¹.     

The influence of a solvent on the aggregation of ruthenium(II) tetra-15-crown-5-phthalocyaninate

The images of ensembles of ruthenium(II) complexes with tetra-15-crown-5-phthalocyanine and axially coordinated triethylenediamine molecules, (R₄Pc)Ru(TED)₂, obtained on an atomic force microscope were analyzed. A comparison with the X-ray structure analysis data was performed to estimate the number and mutual arrangement (architecture) of molecules in supramolecular aggregates depending on the nature of the solvent and the temperature of solutions before casting. Storage at room temperature or heating of a solution of the complex in tetrachloroethane caused the formation of stable supramolecular “wires” 600 nm or more long. The z-scanning method was used to study the third-order nonlinear optical characteristics of solutions of the (R₄Pc)Ru(TED)₂ complex in tetrachloroethane.     

Synthesis and characterization of two zinc(II) macrocyclic Schiff-base complexes containing piperazine moiety, crystal structure of one complex

Two symmetrical and asymmetrical Zn(II) complexes of a pentadentate (N₅) macrocyclic Schiff-base ligands, were prepared via templated [1 + 1] cyclocondensation of 2,6-diacetylpyridine with two different amines containing piperazine moiety. The complexes have been characterized by a variety of methods including, IR, FAB mass spectrometry, elemental analysis and conductivity measurements. The crystal structure of the asymmetric complex, [ZnL¹Br]ClO₄ was determined by X-ray diffraction. It is shown that in the solid state the complex adopts a distorted pentagonal–pyramidal geometry, with the macrocycle in the pentagonal plane and the bromide ion in the axial position.