Undecacarbonyl pyridine triosmium

In a 1.5-L three-necked round-bottomed flask and under a nitrogen atmosphere, a quantity of Os3(CO)11(CH3CN) (700 mg, 0.76 mmol) is dissolved in degassed cyclohexane (1 L). Excess pyridine (0.5 mL, 6.2 mmol) is then added. The solution is stirred at 60 °C for 15 min, after which time the reaction is complete. The progress of the reaction should be monitored by IR spectroscopy so that heating is not continued after completion. This could lead to orthometallation of the pyridine derivative to HOs3(CO)10(C5H4N).2 

The solvent and excess pyridine are removed by a fast stream of nitrogen (in a well-ventilated fume hood), and the yellow-green residue is crystallized from dichloromethane-diethyl ether (x y) at — 10 °C. The product is obtained as yellow-orange crystals. A green powder might precipitate. This is somewhat less pure Os CO fCsHsN). Yield 537mg (74%). 

The compound Os3(CO)j j(C5H5N) is very soluble in acetonitrile, dichl-oromethane, acetone, and methanol, and its solutions are stable to air. It is sparingly soluble in hydrocarbons. Its purity can be checked by IR spectroscopy (dichloromethane solution) v(CO)cm 1 2106(w), 2052(s), 2035(vs), 2008 (s), 1976 (m). Other physical properties have been reported.2 The vacuum pyrolysis of this compound provides a high-yield route to the carbido-dianion [Os10C(CO)24]2-.5 

Using the apparatus and sublimation procedure for trimethylamine oxide described in Section A a suspension of Os3(COi2) (0.5 g, 0.55 mmol) is 

Johnson and J. Lewis, Inorg. Synth., 13,93 (1972). See also section 57 in this volume. 

Inorganic Syntheses, Volume 28 Edited by Robert J. Angelici 1990 by Inorganic Syntheses, Inc. 

The water should be added with care since too much will precipitate some (PPh3)2NCl. The suspension is stirred further for 1 h. The precipitate is then filtered in air, washed with 5 mL of distilled water and S mL of cold methanol, and dried in vacuo overnight to give 58%, 0.414 g, (0.292 mmol) of -nitrido-bis(triphenylphosphorusXl +) /i-carbonyl-decarbonyl-/i-hydrido-triosmate(l —). 

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