Alkali-Metal-Copper Compounds

No compound has been reported for other alkali-metal-copper systems. 

In addition to the above oxides M2O, M2O2, M4O6, MO2 and MO3 in which the alkali metal has the constant oxidation state 4-1, rubidium and caesium also form suboxides in which the formal oxidation state of the metal is considerably lower. Some of these intriguing compounds have been known since the turn of the century but only recently have their structures been elucidated by single crystal X-ray analysis. Partial oxidation of Rb at low temperatures gives RbeO which decomposes above —7.3°C to give copper-coloured metallic crystals of Rb902 ... 

The variation that exists in the 0 F ratio of MMe6Oi5F-type compounds enables isomorphic replacement of alkali metal cations by other cations with appropriate radii. For instance, a copper-containing compound, Cuo.6Nb6Oi4 6F( 4, which crystallizes in a LiNbeOisF type structure, was obtained [255]. 

Copper oxides give rise to numerous accidents. When copper (II) oxide was heated with boron, it gave a highly violent reaction, which caused the melting of the Pyrex container. This is true for alkali metals and titanium as well as aluminium. The reactions lead to liquid metal copper. The emissions of glowing compounds make the reaction very dangerous. 

Tab. 3.6-3. Overview of cage compounds of the type [M Om(REH)x(RE)y] of the monovalent atoms M (alkali metals and copper) and the pnictogen atoms E (P, As).

The lack of homopolyatomic anions for elements to the left of group IV In Table I is noteworthy. Zlntl reported no success with reactions of alkali metal alloys of the copper and zinc family elements and of thallium with liquid ammonia, and the generally stabilizing effect of crypt has not been evident In our own Investigations of alloys of mercury and thallium. On the other hand. It is possible to Isolate a white crypt-potassium gold compound from ammonia solutions at low temperatures which decomposes to elemental gold (+ ) above about -10°C (30). 

Reactions with alkoxides of alkali metals produce yellow copper(I) alkox-ides. For example, reaction with sodium ethoxide yield copper(I) ethoxide, a yellow compound that can be sublimed from the product mixture ... 

Rubidium metal alloys with the other alkali metals, the alkaline-earth metals, antimony, bismuth, gold, and mercury. Rubidium forms double halide salts with antimony, bismuth, cadmium, cobalt, copper, iron, lead, manganese, mercury, nickel, thorium, and zinc. These complexes are generally water insoluble and not hygroscopic. The soluble rubidium compounds are acetate, bromide, carbonate, chloride, chromate, fluoride, formate, hydroxide, iodide,... 

Nonpolar molecular compounds dissolve in nonpolar solvents. Polar molecular compounds and ionic compounds may dissolve in polar solvents. Metals dissolve in other molten metals. These can range from copper, silver, gold, alkali metals dissolving in mercury at room temperature, to chromium, molybdenum, and tungsten dissolving in molten iron. 

Univalent halides—e.g. NH l.AgCl CsCl.CuCl 2KCl.CuCl etc. The halides of the alkali metals do not often unite together to form stable complexes. Univalent copper, silver, and gold form double chlorides with the alkali halides, while the corresponding double bromides of silver and gold and the double iodide of silver have not been made. The facts can be summarized in the form of a scheme due to P. Pfeiffer (1902), where the hyphens represent compounds which have not yet been prepared ... 

CARBIDES. A binary solid compound of carbon and another element. The most familiar carbides are those of calcium, tungsten, silicon, boron, and iron (cemcntitc) Two factors have an important bearing on the properties of carbides (1) the difference in electronegativity between carbon and the second elemenl. and (2) whether the second element is a transition metal. Saltlike carbides of alkali metals are obtained by reaction with acetylene. Those ohlained from silver, copper, and mercury sails are explosive. See also Carbon and Iron Metals, Alloys, and Steels. 

While T. Weyl, J. A. Joannis, and H. Moissan consider that the soln. of the alkali metals in liquid ammonia contain compounds of ammonia and the metal, C. A. Seely, C. A. Kraus, and 0. Ruff and E. Geisel say that the soln. are soln. of the metal in ammonia or mixtures of the metal with a soln. of the metal in liquid ammonia. If the copper-coloured substances be squeezed between folds of cloth in a filter-press, 0. Ruff and E. Geisel separated solid metal, and a sat. soln. of the metal in liquid ammonia. 

---