Jacob Kleinberg

The indium(I) bromide-indium(III) bromide system

Abstract A cryoscopic phase study of the system indium(I) bromide-indium(III) bromide has been made. Evidence has been found for the existence of three intermediate compounds: In2Br3, In4Br7 and InBr2. The results of the phase study have been verified by X-ray powder patterns and by an extraction experiment. In the light of Paulings “radius ratio theory” and previous work on indium halides, it is postulated that In2Br3 exists as In3I[InIIIBr6] and that InBr2 exists as InI[InIIIBr4]. No structure is proposed for In4Br7.

Anodic reductions—V : The reduction of diketones by unipositive magnesium anodically generated

Abstract A series of diketones of the general formula C 6 H 5 CO(CH 2 n COC 6 H 5 has been prepared and subjected to “anodic reduction” in sodium iodide-pyridine solution between magnesium electrodes. In every case hydrolysis of the anolyte following electrolysis yielded a 1:2-diol as the reduction product as evidenced by titration with standard lead tetraacetate solution. The diketones, 1:3-dibenzoylpropane ( n = 3) and 1:4-dibenzoylbutane ( n = 4), gave cis -1:2-diphenyl cyclo pentane-1:2-diol and cis -1:2-diphenyl cyclo hexane-1:2-diol, respectively. On the assumption that the other diketones also gave cyclic 1:2-diols, there is a striking correlation between the initial mean valence number ( V i ) of the magnesium entering solution from the anode and the size of the ring; the lowest V i values were obtained in those instances where the diketones originally in solution gave the most stable cyclic diols. Interpretations are offered for these results and for corrosion phenomena observed.

The anodic oxidation of zinc and cadmium in aqueous solution

Abstract In the absence of oxidizing agents in the electrolyte solution, only the bipositive ions are formed at zinc and cadmium anodes on electrolysis. In the presence of certain oxidizing agents (e.g. nitrate ion), however, both metals dissolve anodically with an initial mean valence number between one and two; in the presence of chlorate ion zinc dissolves with an initial mean valence number between one and two, whereas cadmium exhibits an initial mean valence number of two. In those solutions in which the initial mean valence number of the metal is less than two, its value decreases further with increasing temperature of electrolysis. No unipositive ion of zinc or cadmium could be isolated, and flow experiments indicated that if the unipositive ion is formed it has a very short lifetime with respect to further oxidation to the bipositive state. All of the experimental data can be explained, however, on the hypothesis that the primary anode reaction is the formation of the unipositive ion, which can then be oxidized to the bipositive state either electrolytically or by an oxidizing agent in the solution. The second oxidation can be thought of as competitive between the oxidizing agent and the electrode. This hypothesis is supported by the relation between the initial mean valence number and the quantity of reduced electrolyte in the anolyte solution.

The anodic behaviour of copper in aqueous solutions

Abstract The anodic oxidation of copper in a variety of aqueous electrolytes has been investigated. In the presence of agents (e.g. CN − , Cl − , S 2 O 3 = ) which form stable complexes with copper(I), the metal enters solution solely in the unipositive state over a wide concentration range of electrolyte. With a nitrate, sulphate, or chlorate as electrolyte, copper enters solution with an apparent valence number considerably greater than 1 at 25°C. However, as the temperature is increased, the apparent valence number of copper decreases in the presence of these anions. With chlorate at 98°C, the valence number of copper falls to 1. All the experimental data can be explained on the hypothesis that the primary electrode reaction consists of the formation of unipositive copper.

A kinetic study of the reaction between di-h5-cyclopentadienyltungsten dihydride and benzotrichloride

Abstract The reaction of di- h 5 -cyclopentadienyltungsten dihydride with benzotrichloride proceeds to produce as the only observed products di- h 5 -cyclopentadienyltungsten dichloride and benzal chloride. The reaction was shown to be first order with respect to Cp 2 WH 2 . The relative rate of reaction increases substantially with the use of 3,4-dichlorobenzotrichloride in place of benzotrichloride as the oxidizing agent.

An electrochemical study of hexachlorotungstate(V) and (IV) species and monobipyridine and bis-pyridine derivatives in acetonitrile

Summary The electrochemical behavior of KWCl 6 , K 2 WCl 6 , WCl 5 bipy, WCl 5 (py) 2 , and WCl 4 bipy in acetonitrile has been investigated. WCl 5 bipy and WCl 5 (py) 2 were shown to give the WCl 6 − ion and unidentified unstable cationic species in solution. Substitution of chloride by the π-acceptor 2,2′-bipyridine results in the stabilization of the lower oxidation states, +3 and +2, of tungsten.

THE CHEMISTRY OF COMPLEXES

This chapter presents the nomenclature of complexes and describes their geometry, isomerism, and general properties. It discusses three different approaches to the explanation of bonding in complexes: valence bond theory, molecular orbital theory, and crystal field theory. It further discusses the equilibria among the components of complexes. The chapter illustrates a few practical applications of complexes. The term “complex” is usually reserved for metals combined with donors that also can exist independently either in the pure state or as ions in solution. The molecule or ion that contains the donor atom is called “ligand.” The neutral compound formed between a complex ion and other ions or molecules is called a coordination compound. The coordination number is the number of nonmetal atoms surrounding the central metal atom or ion in a complex. Most metal atoms or ions can accept more than one pair of electrons. The chapter explains the concept of chelation. All metal ions have the ability to form coordination compounds. Bonding in complexes, as in other compounds, is rarely strictly ionic or strictly covalent. The valence bond approach to complex bonding emphasizes covalent bonding, the crystal field theory emphasizes ionic bonding, and the molecular orbital theory brings about a compromise between the two.

Insertion of dichlorocarbene into a tungsten–hydrogen bond

Thermal decomposition of solium trichloroacetate in the presence of tungsten di-h5-cyclopentadienyl dihydride produces tungsten di-h5-cyclopentadienyl dichloromethide hydride.

ATOMS, MOLECULES, AND IONS

This chapter presents the introduction of atoms, molecules, ions, and their weight relationships. It explains the behavior of the atoms. The chapter discusses the symbols used for atoms, how formulas are determined, and solutions and their concentrations. It explains three laws describing the behavior of matter that were known before the acceptance of atomic theory. The chapter further explains how atomic theory applies to those laws. Atoms are found joined together in independent particles called “molecules,” as ions formed by the gain or loss of electrons from the atoms and as free atoms. Ions are held together in compounds by the attraction between the positive and the negative charges of cations and anions.

THE LIQUID AND SOLID STATES; CHANGES OF STATE

This chapter presents the inter-relationships among the gaseous, liquid, and solid phases. It discusses some specific properties of liquids and the solid state. It presents the fundamental topic of crystal structure and the internal arrangements of several types of solids. The chapter discuses the importance of defects and explains the occurrence of solid-state reactions. The term “phase” refers to a homogeneous part of a system in contact with but separate from other parts of the system. The chapter presents Kinetic-molecular theory for liquids and solids. It explains the concept of evaporation, vaporization, condensation and vapor pressure. The chapter illustrates the phase diagram for a solid-liquid-gas system. Surface tension is the property of a surface that imparts membrane-like behavior to the surface. The chapter presents X-ray diffraction, interpreted by the Bragg equation. In neutron diffraction, the incident neutron beam is scattered solely by the nuclei, not by the orbital electrons. That makes neutron diffraction useful in two cases where X-ray diffraction will not work: (1) neutron diffraction can locate very light atoms in the presence of heavier ones, and (2) it can distinguish among atoms with similar numbers of electrons, such as those combined in intermetallic compounds.