Tetrahydrofuran Complexes of Selected Early Transition Metals

Tetrahydrofuran Complexes of Selected Early Transition Metals 135 

TETRAHYDROFURAN COMPLEXES OF SELECTED EARLY TRANSITION METALS 

Few reagents are available for the preparation of organometallic and coordination complexes of the early transition metals. The anhydrous metal halides often lead to disproportionation reactions, and the nitrile derivatives,1 MX (NCR) , are not suitable because of the reactivity of the nitrile with many other reagents. The procedures described below provide simple, high-yield routes to the tetrahydrofuran (THF) complexes of selected, early transition metal halides.2 They have been useful for the synthesis of a wide variety of organometallic complexes.3 

The anhydrous metal halides were obtained from Alfa-Ventron Corp., Danvers, MA 01923. (Only the very best metal halides should be used to produce the yields reported.) All solvents were dried over 4 A molecular sieves and sparged with nitrogen prior to use. 

A 125-mL Erlenmeyer flask equipped with a magnetic stirring bar is charged with 5.0 g (26mmole) titanium tetrachloride dissolved in 50 mL dichloro-methane. Anhydrous tetrahydrofuran (7.62 g, 0.10 mole) is added dropwise, and the solution is stirred at room temperature, under nitrogen, for 15 minutes. ( Caution. Do not attempt to add anhydrous TiCU directly to tetrahydrofuran as a violent, exothermic reaction occurs.) Dry pentane (50 mL) is added, and the solution is chilled to -25° for 1 hour. A bright-yellow solid is collected on a medium fritted funnel and washed with 25 mL dry pentane. The pentane wash plus another 50 mL dry pentane are added to the mother liquor, which is 

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