Synthesis and spectroscopic studies of novel Cu(II), Co(II), Ni(II) and Zn(II) mixed ligand complexes with saccharin and nicotinamide

Four novel mixed ligand complexes of Cu(II), Co(II), Ni(II) and Zn(II) with saccharin and nicotinamide were synthesised and characterised on the basis of elemental analysis, FT-IR spectroscopic study, UV–Vis spectrometric and magnetic susceptibility data. The structure of the Cu (II) complex is completely different from those of the Co(II), Ni(II) and Zn(II) complexes. From the frequencies of the saccharinato CO and SO₂ modes, it has been proven that the saccharinato ligands in the structure of the Cu complex are coordinated to the metal ion ([Cu(NA)₂(Sac)₂(H₂O)], where NA — nicotinamide, Sac — saccharinato ligand or ion), whilst in the Co(II), Ni(II) and Zn(II) complexes are uncoordinated and exist as ions ([M(NA)₂(H₂O)₄](Sac)₂).     

Chirality induction of π-conjugated chains through chiral complexation

Chirality induction of π-conjugated polyanilines through chiral complexation with the chiral palladium(II) complexes was demonstrated to afford the chiral conjugated polymer complexes. Complexation of the emeraldine base of poly(o-toluidine) (POT) with the chiral palladium(II) complex bearing one labile coordination site led to the formation of the chiral conjugated polymer complex, which exhibited an induced circular dichroism (ICD) based on the chirality induction into a π-conjugated backbone. The mirror image of the CD signal was observed with the chiral conjugated polymer complex, which was obtained from the chiral palladium(II) complex possessing the opposite configuration. The chirality of the podand ligand moieties of the palladium complex is considered to induce a propeller twist of the π-conjugated molecular backbone. The crystal structure of the chiral conjugated complex of N-bis(4′-dimethylaminophenyl)-1,4-benzoquinonediimine (L³) as a model compound of the polyaniline revealed a chiral propeller twist conformation of the π-conjugated backbone. Furthermore, chiral complexation with the cationic palladium(II) complexes provided the ionic chiral conjugated complexes.     

Synthesis, catalytic activity and the molecular structure of (μ3-CCH3)Co3(CO)7-μ-(Ph2PCH2PPh2)

Reaction of (μ₃-CCH₃)CO₃(CO)₉ (I) with dppm (dppm = bis-(diphenylphosphino)methane) affords the cluster (μ₃-CCH₃)Co₃(CO)₇-dppm (II). The crystal and molecular structure of II have been determined at −160°C. The dppm ligand bridges one of the three metal—metal edges in the equatorial plane to give a five-membered ring, which adopts an envelope conformation.

Cluster II functions as a catalyst for the hydroformylation of 1-pentene (80 bar of H₂/CO (1/1); 110°C). The results indicate that the dppm bridging ligand stabilizes and activates the cluster for catalysis, and open the way to the synthesis of chiral clusters.     

Heteroleptic platinum(II) complexes of macrocyclic thioethers and halides: the crystal structures of [Pt(9S3)Cl2], [Pt(9S3)Br2], and [Pt(9S3)I2]

The synthesis, spectroscopic, and crystal structures of three heteroleptic thioether/halide platinum(II) (Pt(II)) complexes of the general formula [Pt(9S3)X₂] (9S3=1,4,7-trithiacyclononane, X=Cl⁻, Br⁻, I⁻) are presented. All three 9S3/dihalo complexes form very similar structures in which the Pt(II) center is surrounded by a cis arrangement of two halides and two sulfur atoms from the 9S3 ligand. The third sulfur from the 9S3 forms a long distance interaction with the Pt center resulting in an elongated square pyramidal structure with a S₂X₂+S₁ coordination geometry. The distances between the Pt(II) center and axial sulfur shorten with larger halide ions (Cl⁻=3.260(3) Å>Br⁻=3.243(2) Å>I⁻=3.207(2) Å). These distances are consistent with the halides functioning as π donor ligands, and their Pt---S axial distances fall intermediate between Pt(II) thioether complexes involving π acceptor and σ donor ligands. The ¹⁹⁵Pt NMR chemical shift values follow a similar trend with an increased shielding of the platinum ion with larger halide ions. The 9S3 ligand is fluxional in all of these complexes, producing a single carbon resonance. Additionally, a related series of homoleptic crown thioether complexes have been studied using ¹⁹⁵Pt NMR, and there is a strong correlation between the chemical shift and complex structure. Homoleptic crown thioethers show the anticipated upfield chemical shifts with increasing number of coordinated sulfurs. Complexes containing four coordinated sulfur donors have chemical shifts that fall in the range of −4000 to −4800 ppm while a value near −5900 ppm is indicative of five coordinated sulfurs. However, for S₄ crown thioether complexes, differences in the stereochemical orientation of lone pair electrons on the sulfur donors can greatly influence the observed ¹⁹⁵Pt NMR chemical shifts, often by several hundred ppm.     

Mononuclear Pt(II) and Pd(II) 1,4-dithiolato complexes. Crystal structures of [Pt((−) DIOS) (PPh3)2] and [Pd(S(CH2) 4S)(Ph2P(CH2) 3PPh2)]. Application in styrene hydroformylation

Addition of 1,4-dithiols to dichloromethane solutions of [PtCl₂(P-P)] (P-P = (PPh₃)₂, Ph₂P(CH₂)₃PPh₂, Phd₂P(CH₂)₄PPh₂; 1,4-dithiols = HS(CH₂)₄SH, (−)DIOSH₂ (2,3-O-isopropylidene-1,4-dithiol-l-threitol), BINASH₂ (1,1′-dinaphthalene-2,2′-dithiol)) in the presence of NEt₃ yielded the mononuclear complexes [Pt(1,4-dithiolato)(P-P)]. Related palladium(II) complexes [Pd(dithiolato)(P-P)] (P-P=Ph₂P(CH₂)₃PPh₂, Ph₂P(CH₂)₄PPh₂; dithiolato = ⁻S(CH₂)₄S⁻, (−)-DIOS) were prepared by the same method. The structure of [Pt((−)DIOS)(PPh₃)₂] and [Pd(S(CH₂)₄S)(Ph₂P(CH₂)₃PPh₂)] complexes was determined by X-ray diffraction methods. Pt—dithiolato—SnC1₂ systems are active in the hydroformylation of styrene. At 100 atm and 125°C [Pt(dithiolate)(P-P)]/SnCl₂ (Pt:Sn = 20) systems provided aldehyde conversion up to 80%.     

Palladium(II) coordination and cyclometallated complexes derived from 3- and 5-aryl-substituted pyrazoles

Palladium(II) coordination complexes of nine 3- or 5-arylpyrazoles (phenyl, 2-bromophenyl, or 3-methoxyphenyl), as well as of 3,5-diphenylpyrazole, are reported. A cis-trans mixture of [PdL₂Cl₂] isomers is found in the case of 3-aryl-1-methylpyrazoles, the cis-isomers being transformed into trans by heating. Only trans isomers are isolated with the other ligands. Cyclopalladation of 3-ary]-1-methylpyrazoles can be performed with palladium(II) acetate, and the resultant μ-acetate bridged dimers can be transformed into μ-chloro bridged dimers or acetylacetonate monomers. The structures of the complexes have been characterized by ¹H- and ¹³C-NMR spectroscopy.     

(—)β-Lycorane

Hydrogenation of diacetyllycorine (Ib) was found to be the most effective route for conversion of lycorine (Ia) into β-dihydrocaranine (II). The Hauptmann reduction of 1-deoxy-β-dihydrolycorin-2-one (XII) or the Clemmensen reduction of 1-0-acetyl-β-dihydrolycorinone (XI) followed by hydrogenation afforded (—)β-lycorane (X), which, in view of the sequence of reactions used in these transformations, is considered to have the same configurational structure as the skeleton of β-dihydrocaranine. This lycorane was also obtained by the Hauptmann reduction of β-dihydrocaranone (VIII). A procedure for preparing (—)-lycorane (V) from 1-0-acetyllycorin-2-one (XIV) was also worked up.     

Thermodynamique des complexes metalliques ternaires des amino-acides. II. Etude des systemes Ni(II)—glycine—valine Ni(II)—alanine—valine

Standard enthalpies and entropies of formation for binary and ternary Ni(II) complexes with pairs of the following amino acids as ligands: glycine, DL--alanine and DL-valine, were calorimetrically determined at 25°C in aqueous solution using 1 M ionic strength (NaClO₄).

The results are discussed according to every possible pathway for mixed ligand complex formation and also using the classical statistical methods. Temperature-dependent and temperature-independent components of the thermodynamic data are calculated. In all cases with these ligands involving identical coordination sites, the temperature-independent component of the enthalpy change is closely constant for binary as well as for ternary complexes. All the data show that the stabilization of mixed ligand complexes with respect to the parent binary complexes arises from the entropy term and is maximum for the Ni(II)—glycine—valine system.     

Photodissociation spectroscopy of Mg—Ar

Mg⁺—Ar ion—molecule complexes are produced in a pulsed supersonic nozzle cluster source. The complexes are mass selected and studied with laser photodissociation spectroscopy in a reflectron time-of-flight mass spectrometer system. An electronic transition assigned as X ²Σ⁺ → ²Π is observed with an origin at 31387 cm⁻¹ (vac) for ²⁴Mg⁺—Ar. The ²⁴Mg⁺—Ar spectrum is characterized by a 15 member progression with a frequency (ω′_e) of 272 cm⁻¹. An extrapolation of this progression fixes the excited state dissociation energy (D′_o) at 5552 cm⁻¹. The corresponding ground-state value (D″_o) is 1270 cm⁻¹ (3.6 kcal/mol). The ²Π _, spin—orbit splitting is 76 cm⁻.     

Biacetyl monoxime glycinimine as a selective reagent for palladium and nickel

Biacetyl monoxime glycinimine is proposed as a new reagent for the selective gravimetric and extractive photometric determination of Pd(II) and Ni(II). The reagent forms yellow and rose-red water-insoluble complexes with Pd (pH 0.5–5.5) and Ni (pH 5.0–11.2) respectively. The complexes can be used for direct gravimetric determination or extracted with molten naphthalene. The solidified naphthalene—complex mixture is dissolved in chloroform and measured photometrically. The effects of experimental variables and diverse ions are reported. The proposed reagent offers better selectivity than dimethylglyoxime.     

Synthesis, spectral and structural characterization of two polymeric 1:1 complexes of 2,3-dimethylpyridine and 5-ethyl-2-methylpyridine with copper(II) azide; Cu(2,3-dimethylpyridine) (N3)2 and Cu(2-methyl-5-ethylpyridine) (N3)2

Two new 1:1 ligand complexes of copper(II) azide with disubstituted pyridine ligands, namely catena-di-μ(1,3)-azido-[di-μ(1,1)-azidobis(2,3-lutidine)dicopper(II)] (1) and catena-di-μ(1,1)-azido[di-μ(1,1)-azidobis(2-methyl-5-ethylpyridine)dicopper(II)] (2), have been synthesized and characterized by spectroscopic and X-ray crystallographic methods. The polymeric complex 1 features monodentate 2,3-lut ligands, centrosymmetric di-μ(1,1)-azido-bridged Cu₂N₂ rings, distorted square-pyramidal copper(II) coordination geometry and di-μ(1,3)-azido bridges which link the centrosymmetric binuclear Cu₂(2,3-lut)₂(N₃)₂ moieties to form sheets within the ab plane. In the monoclinic crystals of complex 2, the copper(II) centres are pentacoordinated via N(11), N(21), N(11b) and N(21a) from the azido ligands [Cu---N distances 1.971(5)–2.286(5) Å] and N(1) from the organic molecule at a Cu---N bond length of 2.001(5) Å. Both azido ligands function as μ(1,1) bridges to form chains of polyhedra along the short a-axis of the unit cell. The IR absorption spectra reveal that each of these complexes contains two independent azide ligands. The solid and solution electronic spectra of complexes 1 and 2 show at least three and two strong absorption bands, respectively, associated with N₃⁻ → Cu^II charge transfer transitions. The EPR spectra of powder samples and DMSO solutions at room temperature were recorded and are discussed.     

A examination of the EDTA titration of manganese(II) taking into consideration formation of 1:1 and 1:2 complexes with Eriochrome Black T indicator

In the EDTA titration of manganese(II) with Eriochrome Black T as indicator, the effect of formation of 1:1 and 1:2 manganese(II)—indicator complexes must be taken into consideration. The titration error can be reduced to less than 0.1%. For comparison purpose the titration of zinc(II) has also been studied.     

The evaluation of singlet-triplet separations for [W2(μ-H)(μ-Cl)Cl4(μ-dppm)2] and [W2(μ-H)2 (μ-O2CC6H5)2(P(C6H5)3)2] based on P NMR and crystallographic data

The singlet-triplet separations for the edge-sharing bioctahedral (ESBO) complex W₂(μ-H)(μ-Cl)(Cl₄(μ-dppm)₂ · (THF)₃ (II) has been studied by ³¹P NMR spectroscopy. The structural characterization of [W₂(μ-H)₂(μ-O₂CC₆H₅)₂Cl₂(P(C₆H₅)₃)₂] (I) by single-crystal X-ray crystallography has allowed the comparison of the energy of the HOMOLUMO separation determined using the Fenske-Hall method for a series of ESBO complexes with two hydride bridging atoms, two chloride bridging atoms and the mixed case with a chloride and hydride bridging atom. The complex representing the mixed case, [W₂(μ-H)(μ-Cl)Cl₄(μ-dppm)₂ · (THF)₃] (II), has been synthesized and the value of −2J determined from variable-temperature ³¹P NMR spectroscopy.     

Synthesis of new N-substituted imidazolyl and 1H-1,2,4-triazolyl derivatives of (η-arene)(η-cyclopentadienyl)iron(II) salts

A series of new imidazolyl and 1H-1,2,4-triazolyl derivatives of (η⁶-arene)(η⁵cyclopentadienyl)iron(II) salts have been prepared by reaction of the corresponding chloroarene complexes with the sodium salts of the heterocycles. Good yields of N-substituted products were obtained in all cases under very mild conditions. In contrast to substitution by primary and secondary amines, both chlorines were displaced from [(η⁵-1,2-dichlorobenzene)(η⁵-Cp)Fe][PF₆], indicating electron withdrawal by the imidazolyl and triazolyl groups. Detailed ¹H and ¹³C NMR analysis confirmed this point. NOE difference spectra were used for ¹³C assignments, and evidence for conformational isomers in the 1,2-disubstituted complexes is presented.     

Progres report

This paper provides a brief resumé of our current researches in organometallic chemistry. The first deals with non-classical organolanthanoid chemistry, which has, as targets, subvalent compounds of the early 4f elements (La, Ce, Pr, Nd) and cationic organosamarium(II) and -ytterbium(II) complexes. The second is concerned with new aspects of metal amide chemistry including (a) silver(I) amides and isonitrile complexes of lithium amides; (b) derivatives of aromatic diamides such di(metalamino)cyclophanes; (c) metal silyl complexes derived from insertion of a stable silylene into M(II)---N(SiMe₃)₂ (M = Ge, Sn or Pb) bonds; and (d) reactions of M′---X compounds with 1,3,5-triazine [M′ = Li or Na and X = N(SiMe₃)₂, C(SiMe₃)₃ or CH(SiMe₃)₂] The two other present areas (on subvalent compounds of Group 14 elements and metal 1-azaallyls, β-diketiminates and 1,3-diazaallyls) are reported more cursorily. The Introduction is divided into three section entitled ‘Relationship to the Journal of Organometallics Chemistry’, ‘Reviews (from 1956 to 1995)’ and ‘An outline of principal contributions’.     

The preparation and coordination chemistry of 2,2′:6′,2″-terpyridine macrocycles—VI. Planar hexadentate macrocycles incorporating 2,2′: 6′,2″-terpyridine

The template condensation of 6,6″-bis(-methylhydrazino)-2,2′: 6′,2″-terpyridines L² and L³ with 2,6-pyridinedialdehyde may give a number of different products depending upon the metal ion which is used. In the presence of nickel(II) the products are either the nickel(II) complexes of the 18-membered ring macrocycles L⁴ or L⁵ or the free macrocycles. The metal ion acts as a transient template and is removed in a chloride ion specific demetallation. The use of dimethyltin(IV) as a template results in the formation of complexes of the ring contracted macrocycles L⁶ or L⁷.     

Analysis of the vibration correlation diagram of base · HCl(DCl) H-bonded complexes in Ar matrices: Type II and intermediate type I → II systems

The Fourier transform infrared spectra of the H-bonded complexes between HCl and 4-aminopyridine, 4-aminopyrimidine, 4-hydroxypyridine, 2-hydroxypyridine, benzimidazole and purine were investigated in Ar matrices. From the analysis of these spectra, the H-bonds N HCl appear to be of the pseudosymmetric type II for 4-aminopyridine, 4-aminopyrimidine and 4-hydroxypyridine, while benzimidazole forms a slightly weaker complex. H-bonding of HCl with the bases 2-hydroxypyridine and purine is of the intermediate type I → II. In the case of 4-aminopyrimidine, additional bonding of the Cl atom of HCl to an amino N---H bond yields a closed complex which explains the type II behaviour. In all other cases, bonding of additional HCl molecules to the 1:1 complexes results in proton transfer towards N---H⁺…Cl⁻(HCl)_π species, but n is much lower for type II than for the intermediate type I → II complexes. The results allow us to investigate the vibration correlation diagram and the isotopic ratio ν(HCl)/ν(DCl) for B - HCl complexes in Ar matrices into more detail.     

Synthesis, characterization, and electrochemical, and electrical measurements of novel 4,4′-isopropylidendioxydiphenyl bridged bis and cofacial bis-metallophthalocyanines (Zn, Co)

4,4′-Isopropylidendioxydiphenyl bridged bis-metallophthalocyanines Zn(II) (5) and Co(II) (6) were synthesized from the compound 4,4′-isopropylidendioxydiphthalonitrile (3) and 4,5-bis(hexylthio)phthalonitrile (4). The new cofacial bis-phthalocyanines Zn(II) (7) and Co(II) (8) were synthesized from the corresponding 3 which can be obtained by the reaction of 4,4′-isopropylidendiphenol (1) with 4-nitrophthalonitrile (2). These complexes have been characterized by elemental analysis, UV/Vis, FT-IR, ¹H NMR and MALDI-TOF mass spectroscopies. The electrochemical properties of the complexes were examined by cyclic voltammetry, differential pulse voltammetry and controlled potential coulometry in nonaqueous media. Electrochemical results showed that while there is not any considerable interaction between the two phthalocyanine rings in bisphthalocyanine complexes 5 and 6, the splitting of the molecular orbitals occurs as a result of the strong interaction between the phthalocyanine rings in cofacial complexes 7 and 8.

Measurements of capacitance showed a well defined decrease with increasing frequency and an increase with increasing temperature at lower frequencies.     

Synthesis, structure, and fluorescence of two cadmium(II)-citrate coordination polymers with different coordination architectures

Two novel Cd(II)-citrate complexes were obtained with different metal/ligand ratios through hydrothermal method. Their structures were determined by single-crystal X-ray diffraction analysis. Although their topological structures are both 2-D layer network assemblies, both central Cd(II) ions and Hcit³⁻ ligands display completely different coordination modes. In polymeric complex 1, Hcit³⁻ serves as a μ₁₀-bridged and central Cd(II) ions adopt 6- and 8-coordinated configurations. In contrast, a μ₉-bridged and 6- and 7-coordinated environments between Cd(II) and Hcit³⁻ are established in the polymeric complex 2. Two Complexes remain stable up to approximately 300 °C. The complex 1 exhibits strong fluorescent emission band at 450 nm (λ=346 nm) as well as complex 2 exhibits strong fluorescent emission band at 430 (λ=346 nm).     

Potentiometric study of chloro complexes of some divalent transition metal cations in dimethyl sulphoxide at 25°C

Formation of the chloro complexes of manganese(II), cobalt(II), nickel(II), copper(II) and zinc(II) in DMSO has been studied potentiometrically at 25°C. The con- centration stability constants for the ionic strength of 0.1 mol kg are derived and discussed. The stability of the divalent transition metal cations towards the chloride anion follows the sequence Mn &> Co &> Ni << Cu &> Zn disobeying the Irving-Williams series.