Compound binary

Binary Compounds. The thermodynamics of the formation of HfCl2, of HfCl4, fused sodium and potassium chlorides have been described. The reduction of ZrXj (X = Cl, Br, or I) with metallic Zr or A1 in molten AICI3 has been studied at temperatures from 250 to 360 °C, depending on the halide. The electronic spectra of the initial reaction products were consistent with either a solvated Zr complex or an intervalence Zr -Zr species. Further reduction resulted in the precipitation of reduction products which were identified by analysis and i.r., electronic, and X-ray powder diffraction spectra. The stability of the trihalides with respect to disproportionation was observed to increase from chloride to iodide thus ZrC and ZrCl2,0.4AlCl3 were precipitated, whereas only Zrlj was formed.  

Binary compounds have atoms of only two types (for example, KC1, Na2S, and A12S i). These are generally named as -ide compounds, the more electropositive element being named first. In case the elements are of similar electronegativity, it is customary to name that farthest to the left in the Periodic Table first  

There are two important ways to indicate the proportions of the constituents in compounds. In many cases it is sufficient merely to indicate the oxidation state of the more electropositive element. By the convention suggested by A. Stock (particularly appropriate for saltlike compounds), this is designated with a Roman numeral  

The Stock method is preferable to the classical ous-ic system, for the latter cannot be easily applied to elements with three or more valence states (for example, UCh, UCL, and UCle). 

There is considerable objection to calling FeS2 iron(IV) sulfide because the sulfur atoms are bound to each other, making this compound a disulfide of iron(II) rather than a simple sulfide of iron(IV).  

Naming becomes more difficult if the molecular complexity of a compound changes when it is fused or vaporized. Aluminum chloride is an ionic solid but vaporizes to dimeric molecules the solid is then aluminum trichloride whereas the vapor is dialuminum hexachloride. Similar considerations hold also for FeCl3, P2O5, and a number of additional compounds. Likewise, phosphorus(V) chloride is an appropriate name for PCI5 in the vapor state, but an ideal system of nomenclature should find some way of indicating that the solid consists of equal quantities of PCl and PClJf ions. It is a little difficult to decide just how much information about the structure of a compound must be included in its name before this name is to be considered adequate. 

The ideal vessel for this experiment is a 250ml tubulated retort with a wide neck (at least 15mm in diameter). However, a distilling flask of similar size with a delivery tube 15cm long and 15 mm in diameter sealed on its neck may be used as a substitute. 

Sixty grams of bromine, previously dried with concentrated sulfuric acid are placed in a small dropping funnel with a long delivery tube. The neck of the funnel is protected with a drying tube. 

Ten grams of aluminum (30-mesh or turnings) are placed in the vessel. The funnel is fitted into a rubber stopper covered with aluminum foil and adjusted so that the tip of the funnel is about 50mm from the bottom of the vessel. 

The bromine is added, drop by drop, slowly (Y -l hour) so that the reaction mixture remains liquid. Towards the end of the addition gentle wanning is needed The pale-yellow fluid bromide is then distilled (b.p. 260-270°C) directly into a wide-necked four-ounce glass-stoppered bottle fitted on to the side-arm of the flask or retort with a wad of dry glass wool m.p, 97°C, b.p. 255°C. 

Eighteen grams of iodine, heated to about 180°C are sublimed over 60g of aluminum granules (about 10 mesh) heated at 500-625°C in vacuo or a slow stream of nitrogen or carbon dioxide. Several types of apparatus have been suggested -8 (these may be used also for Fela and Sil ). The almost white product sublimes into the receivers a large excess of metal is used to ensure complete use of the iodine. 

By far the most extensively used synthetic route involves the technique of reductive fluorophosphination developed by T. Kruck and co-workers (174), who have made many important contributions to the development of the field of transition metal-PF3 chemistry. In this method the appropriate metal halide is heated in an autoclave (usually copper-lined) with reducing agents, e.g., copper or zinc, in the presence of PF3(50-500 atm) (method C). For example, 

A few complexes have been made by reduction of their oxides in the presence of PF3 under extremely forcing conditions (method D) (e.g., 300°C, 4000 atm). 

In some cases the presence of a metal reducing agent is superfluous since PF3 can act as both a reducing agent and as a ligand (method E). 

Likewise, the direct synthesis of [M(PF3)4] (M = Ni, Pd, Pt) complexes has been achieved from the appropriate metal powder (method F), or alternatively under very mild conditions from highly reactive forms of the metal (e.g., Ni) generated either from the decomposition of nickel oxalate or nickel tetracarbonyl or activated by sulfide (method G). 

Not surprisingly, in recent years the technique of metal vapor synthesis, in which the metal vapor and PF3 are cocondensed at liquid nitrogen temperatures, has found general application since PF3 is readily condensible (in contrast to CO) and the high volatility of the resulting metal-PF3 complexes facilitates their isolation (method H). 

The reduction is carried out under an atmosphere of argon, not nitrogen. 

The above method is not suitable for obtaining the metals with a stable +2 state, which are only reduced as far as the difluoride (Eu, Yb, Sm). The lanthanide can be removed by distillation. 

The divalent metals Sm, Eu, and Yb have boiling points of 1791, 1597 and 1193 °C respectively, much lower than that of La (3457 °C), so that on heating they are distilled off, their volatility meaning that their removal from the mixture will displace the equilibrium to the right, so the reaction will proceed to completion. 

By ihc end of ihis chapter you should understand the factors determining the stoichiometries of  

The chapter will assume an understanding of Hess law and the thermodynamic terms enthalpy of formation and free energy, together with some prior knowledge of the structures of ionic solids in terms of the close packing of spheres. 

The atomic and ionic properties of an element, particularly IE, ionic radius and electronegativity, underly its chemical behaviour and determine the types of compound it can form. The simplest type of compound an element can form is a binary compound, one in which it is combined with only one other element. The transition elements form binary compounds with a wide variety of non-metals, and the stoichiometries of these compounds will depend upon the thermodynamics of the compound-forming process. Binary oxides, fluorides and chlorides of the transition elements reveal the oxidation states available to them and, to some extent, reflect trends in IE values. However, the lEs of the transition elements are by no means the only contributors to the thermodynamics of compound formation. Other factors such as lattice enthalpy and the extent of covalency in bonding are important. In this chapter some examples of binary transition element compounds will be used to reveal the factors which determine the stoichiometry of compounds. 

In this section, the chemistry of oxides, halides, and similar species will be considered the majority of the papers abstracted reflect the growing interest in MgO as a catalyst. 

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III-V compound semiconductors with precisely controlled compositions and gaps can be prepared from several material systems. Representative III-V compounds are shown in tire gap-lattice constant plots of figure C2.16.3. The points representing binary semiconductors such as GaAs or InP are joined by lines indicating ternary and quaternary alloys. The special nature of tire binary compounds arises from tlieir availability as tire substrate material needed for epitaxial growtli of device stmctures. 

Temary and quaternary semiconductors are theoretically described by the virtual crystal approximation (VGA) [7], Within the VGA, ternary alloys with the composition AB are considered to contain two sublattices. One of them is occupied only by atoms A, the other is occupied by atoms B or G. The second sublattice consists of virtual atoms, represented by a weighted average of atoms B and G. Many physical properties of ternary alloys are then expressed as weighted linear combinations of the corresponding properties of the two binary compounds. For example, the lattice constant d dependence on composition is written as ... 

Nitrogen does form a number of binary compounds with the halogens but none of these can be prepared by the direct combination of the elements and they are dealt with below (p. 249). The other Group V elements all form halides by direct combination. 

Binary Compounds between Nonmetals. For binary compounds between nonmetals, that constituent should be placed first which appears earlier in the sequence ... 

For binary compounds the name of the element standing later in the sequence in Sec. 3.1.1.3 is modified to end in -ide. Elements other than those in the sequence of Sec. 3.1.1.3 are taken in the reverse order of the following sequence, and the name of the element occurring last is modified to end in -ide e.g., calcium stannide. 

Binary Compounds of Hydrogen. Binary compounds of hydrogen with the more electropositive elements are designated hydrides (NaH, sodium hydride). 

Thousands of compounds of the actinide elements have been prepared, and the properties of some of the important binary compounds are summarized in Table 8 (13,17,18,22). The binary compounds with carbon, boron, nitrogen, siUcon, and sulfur are not included these are of interest, however, because of their stabiUty at high temperatures. A large number of ternary compounds, including numerous oxyhaUdes, and more compHcated compounds have been synthesized and characterized. These include many intermediate (nonstoichiometric) oxides, and besides the nitrates, sulfates, peroxides, and carbonates, compounds such as phosphates, arsenates, cyanides, cyanates, thiocyanates, selenocyanates, sulfites, selenates, selenites, teUurates, tellurites, selenides, and teUurides. 

Table 8. Properties and Crystal Structure Data for Important Actinide Binary Compounds...

Arsenic forms the binary compounds arsenous triduoride and arsenic pentafluoride, as well as a series of compounds and the acid of the very stable hexafluoroarsenate ion. 

The halogen fluorides are binary compounds of bromine, chlorine, and iodine with fluorine. Of the eight known compounds, only bromine trifluoride, chlorine trifluoride, and iodine pentafluoride have been of commercial importance. Properties and appHcations have been reviewed (1 7) as have the reactions with organic compounds (8). Reviews covering the methods of preparation, properties, and analytical chemistry of the halogen fluorides are also available (9). 

Three other binary compounds of molybdenum and fluorine are known to exist molybdenum trifluoride [20193-58-2] MoF, molybdenum tetrafluoride [23412-45-5] MoF, and molybdenum pentafluoride [13819-84-6] MoF. Also known are the two oxyfluorides, molybdenum dioxydifluoride [13824-57-2] M0O2F2, and molybdenum oxytetrafluoride [14459-59-7] MoOF. The use of these other compounds is limited to research appHcations. 

The known binary compounds of sulfur and fluorine range in character from ephemeral to rock-like and provide excellent examples of the influence of electronic and stmctural factors on chemical reactivity. These marked differences are also reflected in the diversified technological utiUty. 

Hydrides are compounds that contain hydrogen (qv) in a reduced or electron-rich state. Hydrides may be either simple binary compounds or complex ones. In the former, the negative hydrogen is bonded ionicaHy or covalendy to a metal, or is present as a soHd solution in the metal lattice. In the latter, which comprise a large group of chemical compounds, complex hydridic anions such as BH, A1H, and derivatives of these, exist. 

Many of the binary compounds of the lanthanides, such as oxides, nitrides, and carbides, can exist as non stoichiometric compounds. These form crystals where some of the anions ate missing from the sites the anions normally occupy. 

Binary Compounds. The mthenium fluorides are RuF [51621 -05-7] RuF [71500-16-8] tetrameric (RuF ) [14521 -18-7] (15), and RuF [13693-087-8]. The chlorides of mthenium are RUCI2 [13465-51-5] an insoluble RuCl [10049-08-8] which exists in an a- and p-form, mthenium trichloride ttihydrate [13815-94-6], RuCl3-3H2 0, and RuCl [13465-52-6]. Commercial RuCl3-3H2 0 has a variable composition, consisting of a mixture of chloro, 0x0, hydroxo, and often nitrosyl complexes. The overall mthenium oxidation state is closer to +4 than +3. It is a water-soluble source of mthenium, and is used widely as a starting material. Ruthenium forms bromides, RuBr2 [59201-36-4] and RuBr [14014-88-1], and an iodide, Rul [13896-65-6]. 

Binary Compounds. The fluorides of indium are IrF [23370-59-4] IrF [37501-24-9] the tetrameric pentafluoride (IiF ) [14568-19-5], and JIrFg [7789-75-7]. Chlorides of indium include IrCl, which exists in anhydrous [10025-83-9] a- and p-forms, and as a soluble hydrate [14996-61-3], and IrCl [10025-97-5], Other haUdes include IrBr [10049-24-8], which is insoluble, and the soluble tetrahydrate IrBr -4H20 IrBr [7789-64-2]-, and Irl [7790-41-2], Iridium forms indium dioxide [12030-49-8], a poorly characteri2ed sesquioxide, 11203 [1312-46-5]-, and the hydroxides, Ir(OH)3 [54968-01-3] and Ir(OH) [25141-14-4], Other binary iridium compounds include the sulfides, IrS [12136-40-2], F2S3 [12136-42-4], IrS2 [12030-51 -2], and IrS3 [12030-52-3], as well as various selenides and teUurides. 

Binary Compounds. Three fluorides, PtF [13455-15-7], PtF [37782-184-8], and platinum hexafluoride [13693-05-5], PtF, are well documented. The last is a powerful oxidi2ing agent and can oxidi2e dioxygen and xenon (235). Two chlorides exist, platiaum dichloride [10025-65-7],... 

Table 2. Transport Properties of the Cubic Binary Compound Semiconductors...

Table 3. Band Gaps and Dielectric Properties of Cubic Binary Compound Semiconductors at RT...

Heterostructures and Superlattices. Although useful devices can be made from binary compound semiconductors, such as GaAs, InP, or InSb, the explosive interest in techniques such as MOCVD and MBE came about from their growth of ternary or quaternary alloy heterostmctures and supedattices. Eor the successful growth of alloys and heterostmctures the composition and interfaces must be accurately controlled. The composition of alloys can be predicted from thermodynamics if the flow in the reactor is optimised. Otherwise, composition and growth rate variations are observed... 

Metallic Antimonides. Numerous binary compounds of antimony with metallic elements are known. The most important of these are indium antimonide [1312-41 -0] InSb, gallium antimonide [12064-03-8] GaSb, and aluminum antimonide [25152-52-7] AlSb, which find extensive use as semiconductors. The alkali metal antimonides, such as lithium antimonide [12057-30-6] and sodium antimonide [12058-86-5] do not consist of simple ions. Rather, there is appreciable covalent bonding between the alkali metal and the Sb as well as between pairs of Na atoms. These compounds are useful for the preparation of organoantimony compounds, such as trimethylstibine [594-10-5] (CH2)2Sb, by reaction with an organohalogen compound. 

Arsenic Hydrides. Although there are occasionally reports of other arsenic hydrides, eg, AS2H4, AS2H2 (or AsH), and AS4H2, the only weU-characterized binary compound of arsenic and hydrogen is arsine. 

Boron subhaHdes are binary compounds of boron and the halogens, where the atomic ratio of halogen to boron is less than 3. The boron monohaUdes, BCl, [20583-55-5] bromoborane(l) [19961-29-6] BBr, and iodoborane(l) [13842-56-3] BI, are unstable species that have been observed spectroscopicaHy when the respective ttihaUdes were subjected to a discharge (5). Boron dihaUde radicals have been studied, and stmctural and thermochemical data for these species ( BX2) have been deduced (5). 

Thus the hydride is a very efficient carrier of hydrogen. Upon heating, calcium reacts with boron, sulfur, carbon, and phosphoms to form the corresponding binary compounds and with carbon dioxide to form calcium carbide [73-20-7J, CaC2, and calcium oxide [1305-78-8] CaO. 

Table. Binary Compounds of Carbon and Their Position in the Periodic Table...

For optoelectronics the binary compound semiconductors drawn from Groups 13 and 15 (III and V) of the Periodic Table are essential. These often have direct rather than indirect band gaps, which means that, unlike Si and Ge, the lowest lying absorption levels interact strongly with light. The basic devices of... 

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