Polysilane derivatives of the transition metals III. Preparations and spectra of manganese and iron derivatives

The preparations of derivatives of Mn(CO)₅, Mn(CO)₄PPh₃ and π-Cp(CO)₂Fe containing the polysilyl ligands (Me₃Si)_nMe_3?nSi— (n = 1–3) are presented. The infrared and proton NMR spectra of the compounds are given and for the Mn(CO)₅ derivatives, force constants are derived and discussed in terms of the σ-donor/π-acceptor properties of the silyl ligands.     

ansa-Metallocene derivatives: VIII. Syntheses and crystal structures of ethylene-bridged titanocene and zirconocene derivatives with permethylated ring ligands

Ethylene-bridged titanocene and zirconocene derivatives with permethylated ring ligands, C₂H₄(C₅(CH₃)₄)₂TiCl₂ and C₂H₄(C₅(CH₃)₄)₂ZrCl₂, have been synthesized and their crystal structures determined.     

Dynamics and structure of some tricarbonylferrole-iron tricarbonyl derivatives

A series of compounds of the formula Fe₂(CO)_6-x(PR₃)_x(R′C₂R″)₂ (x = 0, R′ and R″ = Ph, R′ and R″ = H, R′ = Ph and R″ = H; x = 1, K = Ph or n-Bu, and R′ and R″ = Ph) were studied by ¹³C NMR to observe their solution properties. The tricarbonylferrole unit was found to be static from ?125 to +95° C, while the π-Fe(CO)₃ group appeared to be fluxional over the same temperature range. Definite assignments of the carbonyl carbon and ferrole ring carbon resonances have been made. A low temperature single crystal X-ray study of Fe₂(CO)₅PPh₃(PhC₂Ph)₂ demonstrated that the phosphine ligand was attached to the ferrole iron contrary to previous belief based on chemical evidence.     

Continuous-flow determination of reducing sugars in serum by reaction with periodate ions,with use of a flow-through periodate-sensitive electrode

A continuous-flow method for the determination of reducing sugars in serum is described. The sample reacts with an excess of periodate in a flow system and the decrease in periodate

activity is monitored with a periodate-sensitive flow-through electrode. The recorded potential peak heights are indirectly linearly related to the reducing sugar concentration expressed as glucose, in the range 50–290 mg/100 ml. The analysis is completely automated and requires no sample pretreatment, and samples can be analyzed at the rate of 30 per hour with average errors and relative standard deviation of about 1–2%. Comparison with an enzymatic method for serum gave satisfactory results.     

Electrochemical reduction of some rhodanine derivatives at the DME

The electroreduction of two series of rhodanine derivatives has been investigated at the DME. The first wave was assigned to the saturation of the azomethine linkage and the reduction of the ethylenic double bond in series I and II, respectively. On the other hand, the second wave in both series was assigned to the reduction of the C-S group and partly to the catalytic hydrogen evolution catalyzed by these compounds.     

Organotin (IV) derivatives of L-cysteine and DL-penicillamine

The preparations of chlorodimethyl- and chlorodi-η-butyl tin(IV) derivative of L-cysteine, L-cysteine ethyl ester and DL-pencillamine are described. Infrared, n.m.r. and mass spectral data are presented. The compounds contain SnS bonds and suggestions for structures are made.     

The preparation of ferrocenedithiocarboxylic acid derivatives and their spectral properties

Ferrocenedithiocarboxylic acid and various derivatives have been prepared and characterized. The molecular extinction coefficients for the n → π transition of the thiocarbonyl group in the visible spectra of these derivatives are 10–15 fold greater than expected for aromatic dithio acids.     

Adsorption of adenine derivatives on a gold electrode studied by specular reflectivity measurement

The adsorption of adenine, deoxyadenosine, deoxyadenosine-5′-monophosphate,-diphosphate and-triphosphate on a gold electrode has been studied by specular reflectivity measurement in 0.1 M NaClO₄ solution. In the presence of these compounds, a marked decrease in reflectivity was found on reflectivity-potential curves in the potential region more positive than ?0.8 V vs. Ag/AgCl, the decrease being ascribed to the adsorption of them. The magnitude of change in reflectivity was dependent on both the concentration and the electrode potential. The reflectivity change observed in the negative potential region was analyzed quantitatively according to the procedure previously described. The results were elucidated on the basis of the same isotherm as used by Green and Dahms in their adsorption study of aromatic hydrocarbons, and the number of solvent molecules being replaced through the adsorption of one organic molecule and the free energy change of adsorption were obtained. The former is suggestive of a flat orientation of the adsorbed molecule in contact with its adenine moiety on the electrode surface. It is also suggested from the latter that the presence of phosphate groups leads to a decrease in ΔG_ad⁰ resulting from their hydrophilic properties and a repulsive interaction between these groups and the negative charges on the surface.     

Synthetic studies of organodi-π-cyclopentadienyl- titanium (III) derivatives

Two synthetic routes to compounds of the type π-Cp₂Ti^IIIR (R=CH₃, CH₂Si(CH₃)₃, C₆F₅) have been investigated: (a) chemical reduction of π-Cp₂Ti^IV(R)Cl by zinc or aluminum metal in tetrahydrofuran, and (b) conventional organometallic syntheses using organo-lithium or -magnesium reagents and [π-Cp₂Ti^IIICl]₂. The preferred route is via an organolithium reagent, since chemical reduction gives a mixture of products. Green, monomeric complexes (R = CH₂Si(CH₃)₃, C₆F₅) were isolated and characterised. From the reaction of π-Cp₂Ti^IVCl₂ and trimethylsilylmethyllithium in a 1/1 ratio, π-CpTi^IV [CH₂Si(CH₃)₃]₃ was obtained. Unlike π-Cp₂Ti^IIIC₆F₅, π-Cp₂Ti^IIICH₂Si(CH₃)₃ does not form a blue complex with molecular nitrogen.     

Photo-induced degradation reactions of some alkyl- and aryl-carbonyl derivatives of manganese,molybdenum and tungsten

Photo-induced degradation of CH₃Mn(CO)₅ in pentane solution results in the formation of Mn₂(CO)₁₀, methane and carbon monoxide. Both CH₃D and CH₄ are formed when CH₃Mn(CO)₅ is photolyzed in C₆D₆. Photolysis of C₆H₅CH₂Mn(CO)₅ in pentane solution produces Mn₂(CO)₁₀, toluene and bibenzyl. Analogous photodegradation of C₆H₅Mn(CO)₅ in pentane solution yields Mn₂(CO)₁₀, benzene and carbon monoxide, but not biphenyl. The thermally unstable complex C₂H₅Mn(CO)₅ was studied by photolyzing it in solution at ?40°C. GC analysis indicates that both ethylene and ethane are formed, and that the mole ratio of these products is dependent on the initial concentration of C₂H₅Mn(CO)₅. These results are consistent with a β-hydrogen elimination mechanism for this reaction. Photolysis of CpMo(CO)₃CH₂C₆H₅ in pentane solution produces [CpMo(CO)₃]₂ and toluene, whereas photolysis of CpW(CO)₃CH₂C₆H₅ affords [CpW(CO)₃]₂, CpW(CO)₂(η³-benzyl), toluene, and a small amount (2%) of bibenzyl. When CpM(CO)₂(η₃-benzyl) (M = Mo, W) complexes are subjected to photolysis under similar conditions, the only identifiable product is toluene. CpW(CO)₃C₆H₅ degrades photochemically in pentane solution to form [CpW(CO)₃)₂ and benzene, together with a small amount (6%) of biphenyl.     

New imine-phosphine chelating agents and their molybdenum(O) derivatives

The aldehyde o-Ph₂PC₆H₄CHO condenses with a variety of functionalized amines to afford several new ligand which form stable mono- and bimetallic complexes with molybdenum(O).     

Electron density distribution in ferrocene analogues of stilbene. Interaction of substituents and molecular groups in ferrocene derivatives

Two techniques, ¹³C NMR and cyclic voltammetry, are utilized to determine the change of electron density distribution caused by substituents in ferrocene analogues of stilbene. The interactions of substituents and some molecular groups in four series of ferrocene derivatives is discussed and the transmission coefficients of these groups are presented.     

ansa-Metallocene Derivatives : IV. Synthesis and molecular structures of chiral ansa-titanocene derivatives with bridged tetrahydroindenyl ligands

A synthesis for racemic ethylene-bis(4,5,6,7-tetrahydro-1-indenyl)titanium dichloride is described. The molecular structures of this compound, of its meso- isomer and of a binaphtholate complex of the (S,S)-enantiomer have been determined. Cleavage of this binaphtholate complex gives the pure (S,tS)-enentiomer.     

ansa-Metallocene derivatives: VII. Synthesis and crystal structure of a chiral ansa-zirconocene derivative with ethylene-bridged tetrahydroindenyl ligands

The chiral ansa-zirconocene derivative ethylenebis(4,5,6,7-tetrahydro-1-indenyl)-zirconium(IV) dichloride has been prepared by reaction of dilithiobis(indenyl)ethane with ZrCl₄ and subsequent hydrogenation. The product has been shown to be the 1-R,S rather than meso-metal-ring linkage stereoisomer by an X-ray determination of the molecular structure.     

Organometallic oxime and allied derivatives II. Synthesis and properties of some tri-n-butylgermanium oximates

Tributylgermanium oximates have been prepared by reactions (a) of tributylgermanium chloride with (i) oximes in the presence of a base, (ii) sodium oximates, and (iii) organotin oximates, as well as (b) of tributylgermanium ethoxide and oxide with oximes.The derivatives have been characterised by elemental analyses, molecular weight measurements and IR spectra. Their reactions have been studied in detail.     

The redox properties of organotransition-metal complexes IV. The activation of cyclic polyolefiniron tricarbonyl derivatives by one-electron oxidation

Cyclic polyolefiniron tricarbonyl derivatives [Fe(CO)₂L(C_nH_m)] (L = CO or phosphorus donor) and oxidising agents such as Ag⁺ or [NO]⁺ in CH₂Cl₂ give reactive paramagnetic cations [Fe(CO)₂L(C_nH_m]⁺ which can abstract hydrogen from the solvent to give [Fe(CO)₂L(C_nH_{m + 1})]⁺.     

π-Cyclopentadienyl-like derivatives of cobalt: synthesis of indenyl- and fluorenyl-bis(phosphite)-cobalt(I)

The compounds {Co(C₉H₇)[P(OR)₃]₂} (C₉H₇ = indenyl) and {Co(C₁₅H₉)[P(OR)₃]₂} (C₁₃H₉ = fluorenyl) (R = C₂H₅, i-C₃H₇) have been prepared by treating {CoBr[P(OC)₃]₃} with NaC₉H₇ and NaC₁₃H₉, respectively. The ¹H, ¹³C NMR, IR, and mass spectra of the new compounds are discussed. The preparation of {Co(C₉H₇)(CO)[P(OR)₃]} and {Co(C₁₃H₉)(CO)[P)OR)₃]} is also reported.     

Thermal studies on purine complexes. VII. 8-theophylline derivatives and their silver(I) complexes

Four theophylline derivatives: 8-ethyltheophylline (ETH), 8-isopropyltheophylline (IPH), 8-propyltheophylline (PRH), and 8-phenyltheophylline (FTH) have been synthesized and characterized by spectroscopic techniques and thermal analysis. The melting points of these theophylline derivatives increase with the molecular weight, from 263.8°C (ETH) to 384.7°C (FTH). The values of the fusion enthalpy increase in the same order, from 28.4 kJ mol⁻¹ (ETH) to 36.5 kJ mol⁻¹ (FTH).

The interaction of these theophylline derivatives with Ag(I) has been studied by means of spectroscopic techniques, TG, DTG and DSC. In all cases, the pyrolysis of these compounds gave metallic silver.