The reaction of methylborylene with cyclohexene and some other olefinic compounds

Some potential methylborylene-generating systems were investigated, using cyclohexene as the trapping agent. Methylborylene, generated by the system 2C₈K/MeBBr₂, reacts with cyclohexene to yield 2-methyl-2-boratricyclo-[7.4.0.0^3.8]-tridecane (MBTT) Ia. In the course of the work an isomer of MBTT was synthesized along a completely different route and compared with Ia. With the system 2C₈K/MeBBr₂, only cyclic olefins were converted to analogues of MBTT. An acyclic olefin and a conjugated diene yielded only haloboration products. Possible mechanisms leading to the formation of MBTT Ia are discussed.     

The effect of selfassociation of mercurated carbonyl compounds of mercury-199 chemical shifts

Temperature and concentration dependences of mercury-199 chemical shifts in benzene solutions of bis(methylethylketone)mercury Hg(CH₂COC₂H₅) (I) and α-bis(methylacetoacetone)mercury Hg(CH₂COCH₂COOCH₃)₂ (II) are determined by the ¹H-{¹⁹⁹Hg}method. The NMR data obtained and the IR spectra are indicative of selfassociation of I and II in solution with the formation of weak intermolecular coordination bonds Hg ← :OC. The enthalpies of complex formation calculated on the assumption of one mercury atom bonding with only one carbonyl function are equal to ?3.2 ± 0.1 kcal/mol and ?2.2 ± 0.1 kcal/mol for I and II, respectively.     

The reaction of aqua-(ethylenediaminetetra-acetato)ruthenium(III) with o-phenylenediamine under aerobic conditions

An electron-transfer reaction between [Ru(III)(Hedta)(H₂O)] and o-phenylenediamine in the presence of O₂ takes place to give a Ru(II)-edta complex with coordinated (bidentate) o-benzoquinone diimine. The complex obtained has been characterized by analysis, magnetic measurements, electronic, IR, ¹H and ¹³C NMR spectral data.     

Thermal reaction of aquaammineruthenium(III) complex with amino acid or imidazole derivative in the solid state

Intermolecular thermal-substitution reaction between aquaammineruthenium(III) complex and amino acid or imidazole derivative has been investigated in the solid state by the TG-DTA method. Pentaammineruthenium(III) complexes containing amino acid or imidazole derivative have been obtained directly by the thermal reactions. Glycine, β-alanine, and γ-aminobutyric acid coordinate to Ru(III) through their carbonyl oxygen, and imidazole does through its N(3) atom. Distinct coordination site is provided in the complex with histidine and/or adenine: the bonding site depends on the outer-sphere anion of aquaammine complex. The N(3) atom of the histidine and N(7) atom of the adenine coordinate to Ru(III) taking the paratoluenesulphonate salt of aquaammineruthenium(III) into the reaction. When the methanesulphonate salt is used, the nitrogen atom in the side-chain amino-group participates in complexation. Direct chelation of the glycine, histidine, and adenine to the deaquated cis-diaquatetraammineruthenium(III) complex has been confirmed.     

Kinetics of the reaction of Di-μ-acetatodi-μ-oxalatodiaquodiruthenium(II,III) anion with N-(2-hydroxyethyl)-ethylenediaminetriacetatoaquotitanium(III)

Reduction of [Ru₂(CH₃COO)₂(C₂O₄)₂(H₂O)₂]^? by N-(2-hydroxyethyl)-ethylenediaminetriacetatoaquotitanium(III) [Ti(HEDTA)] involves several distinct stages. The first stage has a half-time of less than 1 ms, and is interpreted as a substitution reaction leading to a multinuclear intermediate. The second stage has a second-order rate constant of 5 x 10₃M^?1s^?1 [25°C, μ = 0.1 m (LiCF₃SO₃)]. The rate-limiting process for the second stage is electron transfer within the assembled multinuclear complex. Subsequent slower stages correspond to breakup of the multinuclear Ru(II)₂-Ti(IV) complex formed by electron transfer. The overall rate of reduction of this oxidant by Ti(HEDTA) is less than the corresponding rate for the reaction in which Ti³⁺ acts as reductant, mainly because the stability of the binuclear complex is reduced by the presence of the aminoacid ligand. The data are consistent with the conclusion that the ligand increases the rate of intramolecular ET, probably by reducing geometric change associated with oxidation of Ti(III) to Ti(IV).     

Equilibrium study of the systems of aluminium(III), gallium(III) and indium(III) with mercaptoacetate, 3-mercaptopropionate and 2-mercaptobenzoate

Equilibrium studies were carried out by pH-potentiometry on the systems of aluminium(III), gallium(III) and indium(III) with mercaptoacetate (MerAc^2?), 3-mercaptopropionate (MerPr^2?) and 2-mercaptobenzoate (MerBe^2?). It was found that the complex-forming properties of the Al³⁺ ion towards these mercaptocarboxylic acid ligands differ from those of Ga³⁺ and Al³⁺. Under the conditions of the study, Al³⁺ forms only hydroxo complexes, while Ga³⁺ and In³⁺ form relatively stable complexes involving the simultaneous coordination of the carboxylate and the deprotonated mercapto group. In all cases the equilibrium systems can be described without the assumption of polynuclear complexes. The complexes Ga(MerAc)₂ and Ga(MerBe)₂ show marked stability; this was interpreted in terms of back-coordination and of interaction between the d¹⁰ electrons of the Ga³⁺ ion and the empty d orbitals of the S donor atom. Complexes of composition ML_i are not formed in the Ga³⁺-MerPr^2? system; this points to the importan roles of the number of atoms in the chelate ring and the higher stability of the Ga(III)-hydroxo complexes.     

NMR study of extracted compounds of trioctylalkylammonium with rare earth nitrates

¹H and ¹³C NMR was used to investigate the structure of ion pairs formed by trioctylalkylammonium (alkyl = CH₃-C₈H₁₇) cation and rare earth-containing anions in nitrobenzene. The cation-anion distance in the investigated compounds increases from trioctylmethyl to trioctylbutylammonium salt, remaining constant with further growth of the n-alkyl chain. The ion pair formation changes the conformation equilibrium of the cation alkyl radicals to make easier the cation-counter-ion contact.     

Evidence for absence of an inverted region for Ru(III)-Ti(III) outer-sphere electron-transfer reaction

A lower limit of 10⁸ M^?1 s^?1 was obtained for the 2nd-order rate constant at 25°C for the reduction of Ru(bpy)₃³⁺ by Ti(III) in an aqueous medium of ionic strength 1.0 M and pH range 0–2. The theoretical implications of this result are discussed.     

Metal π-allyl chemistry III. The preparation of π-allylpalladium complexes from palladium(II) salts

A number of routes for the preparation of π-allylpalladium complexes from palladium(II) salts were investigated with a view to obtaining a quantitative yield. Quantitative yields were obtained rapidly when a stream of ethylene was passed through an aqueous solution of Na₂PdCl₄ and the allylic chloride, and more slowly on vigorously shaking an aqueous solution of Na₂PdCl₄ with a 3-fold excess of allyl chloride.Spectroscopic evidence is presented to confirm that the first stage of the reaction of allylic compounds with palladium(II) salts involves the formation of an olefinic complex. It is found that such palladium(II)olefin complexes of CH₂CHCH₂X are very much less susceptible to nucleophilic attack when X = Cl than when X = C₅H₁₁, OH or OAc, which are all attacked rapidly by nucleophilic solvents, such as methanol, with deposition of palladium metal.     

Kinetic study of the reaction of meso-tetrakis (p-trimethylammoniumphenyl)porphinatodiaquorhodate(II) with chloride,bromide, iodide,hexacyanocobaltate(III) and thiocyanate ions in aqueous solution

The reaction of Cl^?, Br^?, I^?, Co(CN)₆^3? and NCS^? with meso-tetrakis (p-trimethylammoniumphenyl)porphinatodiaquorhodate(III), [RhTAPP(H₂O)₂]⁵⁺, has been studied at 15, 25 and 35°C in 0.1 M [H⁺] with μ = 1.00 M (NaNO₃). The value of the acidity constant, K_al, at 25°C is 4.39 × 10^?9 M. The reactions are first order in anion concentration up to 0.9 M. The values of the stability constants, K₁, and the second order rate constants, k₁, for the reaction with Cl^?, Br^?, I^?, Co(CN)₆^3? and NCS^? are respectively 0.23 M^?1 and 2.5 × 10^?3 M^?1 s^?1, 1.1 M^?1 and 6.92 × 10^?3 M^?1 s^?1, 40.0 M^?1 and 17.0 × 10^?3 M^?1 s^?1, 550 M^?1 and 20.0 × 10^?3 M^?1 s^?1, 3400 M^?1 and 20.9 × 10^?3 M^?1 s^?1. The porphine greatly labilizes the Rh(III). There has been about a 500-fold increase in the rate constant for substitution compared to that of [Rh(NH₃)₅H₂O]³⁺. The substitution rates are however about the same as for [Rh(TPPS)(H₂O)₂]^3?, indicating that the overall charge on the complex plays only a minor role. The kinetic results indicate that dissociative activation is occurring in these reactions.     

Structural studies in main group chemistry III. Tin-119m mössbauer investigation of some tin-nitrogen bonded compounds

The tin-119m Mössbauer data are presented for several classes of organotin- nitrogen bonded compounds, including N-stannylamines, -imines, -amides, and -carbamates. Thc structures of the N,O-bis(trialkylstannyl)carbamates are discussed. Those derivatives possessing the Sn-NR-C(O)X group are intermolecularly associated via carbonyl→tin coordination, the strength of the coordination varying with X in the manner H ≈ OSnR₃ > OR.     

Optical activity of compounds formed by aminocomplexes of Co(III) and carbohydrates—I

The preparation of aminocomplexes of Co(III) containing d-ribose, l-sorbose or d-glucosamine as second ligand is described. Their spectral features and optical activity are reported. Formation in solution of complex species with other chosen carbohydrates gives ground for discussion as to the origin and sign of the observed Cotton effects.     

Polarographic study of Eu(III)-succinate-ethylenediamine and Eu(III)-malonate-ethylenediamine mixed systems

The mixed complexes of Eu(III) with succinate (succ^2?) and malonate (mal^2?) and ethylenediamine (en) have been studied polarographically at 25°C and at constant ionic strength, μ = 0.1 (NaNO₃) and pH 6. The reduction of the complexes in each case is quasi-reversible and diffusion-controlled. In each system three mixed complexes are formed, viz. [Eu(succ)(en)]⁺, [Eu(succ)(en)2]⁺ and [Eu(succ)₂(en)]^? with stability constants log β₁₁ = 9.2, log β₁₂ = 17.5 and log β₂₁ = 11.7; and [Eu(mal)(en)]⁺, [Eu(mal)₂(en)₂]^? and [Eu(mal)₃(en)]^3? with stability constants log β₁₁ = 11.4, log β₂₂ = 19.08 and log β₃₁ = 13.5 respectively.     

A 19F NMR study of the transmission of electronic effects in triarylantimony and triarylbismuth compounds. A comparison with the nitrogen- and carbon-containing analogues

A ¹⁹F NMR study of the transmission of electronic effects has been made for the systems Ar₂EC₆H₄F-4 (E = Sb, Bi, CH, N). The fluorine chemical shifts obtained are correlated with the polar constants (Σσ^o and Σσ) of the substituents, suggesting that electronic effects are transmitted through the SbC_ar, BiC_ar and CC_ar bonds predominantly by an inductive mechanism, whereas the transmission through the NC_ar bonds is contributed to significantly by classical resonance effects due to competitive conjugation of the lone pair with the aromatic rings, and the substituents therein. A dual parameter correlation of the fluorine chemical shifts with the inductive (σ_I) and resonance (σ^o_R and σ_R) parameters of the substituents in the aromatic rings has led to similar conclusions. The inductive transmission through the bridging Sb and Bi atoms has been assigned to the absence of conjugation of lone pair and vacant d-orbitals of the metals with π-electron systems of the aromatic rings. On the basis of the values of the ? coefficients for the correlation equations obtained it has been established that the transmitting ability of the BiC_ar bonds is close to that of the C_alC_ar bonds and considerably lower than the transmitting ability of the NC_ar bonds.     

Organometallic Compounds XIV. Formation of novel [4]ferrocenophanes by the acid-catalyzed reaction of 1,1′-bis (α-hydroxy-α-phenylethyl) ferrocene

The acid-catalyzed reaction of 1,1′-bis(α-hydroxy-α-phenylethyl)ferrocene gave several [4] ferrocenophanes including a peroxide derivative. Their structures have been confirmed by spectrometric methods and from a study of their reaction behavior.     

The reaction of lithiun aluminium hydride with carbon dioxide or sodium bicarbonate

The reaction of LiA1H₄ with CO₂ or NaHCO₃ at elevated temperatures has been investigated. Methane and ethylene are the primary products of each reaction. These molecules are probably the “explosive” reaction products formed when CO₂ fire extinguishers are used on LiAlH₄ fires.