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2167. MANCHOT, W., AND MANCHOT, W. J. [Preparation of Ruthenium Carbonyls and Nitrosyls.] Ztschr. anorg. Chem., vol. 226, 1936, pp. 385-415; Brennstoff-Chem., vol. 17, 1936, p. 232; Chem. Abs., vol. 30, 1936, p. 5139. By reacting CO with Ru at 180° and 200 atm., an easily volatile Ru carbonyl is formed, which separates out at –80° in colorless crystals, melting at –22 to a colorless, optically sensitive liquid, which itself decomposes a little above its melting point with evolution of gas and formation of a yellowish color. After some time it crystallizes into beautiful orange flakes until finally the liquid phase completely disappears. The conversion occurs instantaneously at 50°. The formula of the volatile carbonyl is Ru(CO)5, that of the orange crystals Ru2(CO)9. It is insoluble in H2O and easily soluble in C6H6, alcohol, CHCl3, CCl4, and benzine; but the solutions on standing become yellow, indicating formation of Ru2(CO)9. In alkaline solution, it is a strong reducing agent. With I in C6H6, RuI2(CO)2 is probably formed. Ru2(CO)9 is easily produced by heating Ru(CO)5 to 50°. It can be easily crystallized from C6H6. The crystals are quite stable to air and light, insoluble in H2O, and soluble in organic solvents. Its solution in glacial AcH becomes lilac in direct sunlight. It is extremely stable and is believed to be due to a change in molecular size. Heated in air, Ru2(CO)9 begins to decompose at 150°. With I it forms RuI2(CO)2, orange-red. Ru(CO)5 can also be prepared by heating 1 gm. RuI3 with 5 gm. Ag in a Cu-coated autoclave with CO at 170° and 455 atm. for 24 hr. A green Ru carbonyl is formed as a byproduct in the conversion of Ru(CO)5 into Ru2(CO)9. It is amorphous and insoluble in organic solvents but is soluble in pyridine and concentrated HCl. In general, it is similar to Fe(CO)4 and may be the analogous Ru compound. If Ru2(CO)9 is heated in dry NO for 13 hr. at 120°, the temperature then gradually is raised to 150°, and the NO gradually is displaced by dry N2, a red, crystalline product is obtained, Ru(NO)5. It is very difficult to obtain this uncontaminated with Ru(CO)5. It easily gives off NO, especially when moist. It is insoluble in H2O, Et2O, C6H6, slightly soluble in alcohol, somewhat better in acetone, and soluble in pyridine. It is reduced with H2 at 220°; NH3 is formed. MANCHOT, W. J. See abs. 2167. |