Selenium antimony halides

The most important range for inorganio chemicals is between 1 40 and 1 70. But there are some substances, such as certain oxides and sulphides, whose indices lie well above this range, or even well above 2 0. Media which are liquid at room temperature and have such high refractive indices are not available, but certain mixtures of substances which solidify to glasses may be used. A little of the medium is melted on a microscope slide, the substance under examination is dusted into the melt, a cover-glass is pressed on, and the slide is then allowed to cool. Substances which have been used in this way are mixtures of piperine with arsenic and antimony tri-iodides (for indices 1 7-2 1), mixtures of sulphur and selenium (2-0-2-7)—for details, see Larsen and Berman (1934)—and mixtures of the halides of thallium (Barth, 1929). 

Aside from these three classes (species with unfilled inner subshells, with unpaired electrons, or with two different oxidation states of the same element), there are a number of colored inorganic substances about which generalizations may be set up only with difficulty. Among these are many of the elementary nonmetals, a large number of covalent salts (such as mercuric iodide, cadmium sulfide, silver phosphate and lithium nitride), a number of nonmetal halides (iodine monochloride, selenium tetrachloride, antimony tri-iodide, etc.), and the colored ions, chromate, permanganate, and Ce(H20) v, whose central atoms presumably have rare-gas structures. 

Class I. ELEMENTS. A. Metals. Cubic copper, silver, gold, iron, platinum, iridium. - Tetragonal tin. - Rhombohedral and Hexagonal arsenic, antimony, bismuth, tellurium, (Os, Ir). - B. Metalloids. Cubic diamond. - Hexagonal graphite. - Orthorhombic sulfur, iodine. - Monoclinic sulfur, selenium. - Class II. SULFIDES. - Class HI. HALIDES. -Class IV. OXIDES, divided into SIMPLE OXIDES and COMPLEX OXIDES, such as CARBONATES, PHOSPHATES, SILICATES, BORATES and SULFATES. 

Rose investigated the compounds of ammonia with titanium and stannic chlorides, and with chlorides of sulphur, selenium, phosphorus, arsenic, antimony, aluminium, and iron, as well as the compounds of ammonia with anhydrous halides, sulphates, and nitrates of several metals. He discovered antimony pentachloride by acting on antimony with excess of chlorine, and an interesting compound of it with sulphur chloride, obtained by the action of excess of chlorine on antimony trisulphide. He formulated this as SbCl5,3SCl4, but the pure compound, which can be obtained in crystals, is SbClg, SCI4. ... 

From electrochemical data it may be concluded that the solvates are composed of complex ions formed by halide ion transfer thus the system SbClg-SeOClj gives rise to SeOCl and SbCl ions. Polynuclear complexes are also possible. However, a structure determination has shown that crystals of the solvates SbCl. SeOCl comprise discrete SbCl. SeOCl molecules with an octahedral configuration in which five chlorine atoms and one oxygen atom coordinate the antimony atom. The coordination of the selenium atom is approximately pyramidal. The Sb-0 distance corresponds to a single bond distance indicating that the interaction between the solute and the solvent molecule is strong. 

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