Sodium Benzophenone Ketyl Solution

A solution of sodium benzophenone ketyl is exceedingly reactive, and is immediately decolorized by air or traces of water, alcohols, and so on. The solution should therefore be kept under nitrogen at all times. Aliquots may be removed using a dry syringe via the septum cap. Under these conditions, the solution appears to be stable for 2 days. 

The complex Ru3(CO)n(PMe2Ph) is a reasonably air-stable red-orange crystalline solid (mp 104-106 °C), which dissolves readily in organic solvents. The IR spectrum (hexane) shows v co) bands at 2096 (m), 2044 (s), 2028 (s), 

DECACARBONYL(DIMETHYLPHENYLPHOSPHINE)-(2-ISOCYANO-2-METHYLPROPANE)TRIRUTHENIUM, Ru3(CO)io(CN-/-Bu)(PMe2Ph) 

The amount of Na[Ph2CO] solution required depends on how dry the reaction mixture is. When the reaction appears visually to be complete, a small aliquot should be examined (solution IR spectrum) to ensure that the precursor cluster complex has reacted completely [using the 2096 cm v,co) band of Ru3(CO)j i(PMe2Ph)]. Alternatively, the progress of the reaction may be monitored by TLC (thin layer chromatography) (silica gel, petroleum ether eluant). 

After the reaction is determined to be complete, solvent is removed (rotary evaporator), and the resulting deep red oil is extracted with two 10-mL aliquots of warm ( 40°C) petroleum ether (boiling range, 40-60 °C). The extracts are filtered, concentrated to 5 mL under vacuum, and cooled at — 10 °C overnight to give Ru3(CO)io(CN-t-Bu)(PMe2Ph) (0.052 g, 42%) as deep red crystals. 

A 50-mL Schlenk tube, previously kept overnight in a hot oven, is flushed with nitrogen while cooling. After attaching a gas inlet to the side arm, the 

---

Reagent grade ether was dried by distillation under argon from a purple solution of sodium benzophenone ketyl. 

The tetrahydrofuran was dried by distilling from lithium aluminium hydride and then from sodium benzophenone ketyl (generated by adding small pieces of sodium metal and benzophenone) directly into the reaction flask. A blue-black color of the ketyl solution indicates dryness. The checkers purified tetrahydrofuran by distillation from sodium hydride dispersion under nitrogen, and used it immediately. 

Dibutyl ether (Aldrich, 99%) is dried and freed from dissolved molecular oxygen by distillation under nitrogen from a solution of the solvent and sodium benzophenone ketyl. 

A solution of sodium benzophenone ketyl is prepared by adding benzophenone (Fisher Scientific) (10 g) to THF (100 mL) containing excess sodium. 

In 1979, Butts and Schriver showed that the reaction of [Fe(CO)5] and PR3 to give [Fe(CO)4PR3] occurs cleanly, fairly rapidly, and in good yield when sodium benzophenone ketyl (BPK) is added to the solution in a catalytic amount.121 This discovery was remarkable because [Fe(CO)5] normally requires rigorous thermal or photochemical conditions to afford even poor yields of the CO substitution product, [Fe(CO)4L], and is reported123 to have a half-life of years for CO exchange at room temperature. BPK is known to reduce [Fe(CO)5] to a variety of polynuclear iron car-... 

Anhydrous diethyl ether and anhydrous tetrahydrofuran (THF) were obtained from Fisher Scientific Company. They were redistilled under nitrogen from dark blue or purple solutions of sodium benzophenone ketyl immediately prior to use. All transfers of these and other anhydrous materials were performed with syringes or stainless steel cannulas while carefully maintaining a nitrogen atmosphere. 

Diphenylphosphine (37.2 g, 0.2 mole) and isopropyl phenylvinylphos-phinate (42 g, 0.2 mole) are mixed with 300 ml of tetrahydrofuran (freshly distilled, under nitrogen, from sodium-benzophenone ketyl). Sufficient KO-(t-Bu) is added until the solution becomes hot and yellow to orange in color (the catalyst is hydrolyzed fairly rapidly by atmospheric moisture, but the additions can be made using a spatula, provided that the bulk of the catalyst is kept under nitrogen and the transfers are made rapidly). If the reactants are pure and the tetrahydrofuran is scrupulously dry, only 20-30 mg is required to produce the heat and color. This solution is boiled under reflux for 16 hr. During the reflux period, the color of the solution should fade, becoming pale yellow to colorless. 

To the polymer [NPCl2]2—[NP(CH3)(CH2SiMe3)] and the residual cyclic species, ge/n-N3P3Cl4(CH3)(CH2SiMe3), in an airless flask is added 300 mL of dry THF (distilled over sodium benzophenone ketyl). This mixture is stirred under an atmosphere of dry nitrogen until the contents of the broken tube dissolve (3-4 hr). The THF solution is then transferred to a 500-mL addition funnel under an atmosphere of nitrogen via a double-tipped syringe needle. 

All operations are performed under nitrogen or under vacuum using standard Schlenk techniques. Diethyl ether, hexane, and THF are freshly distilled from sodium benzophenone ketyl. The compounds [Rh(V-C0D)C1]2, NiCl2(PMe3)2, and r-BuPH2 are prepared by the literature methods. A solution of the compound (H)(f-Bu)PLi is prepared by the addition of /i-BuLi to a solution of f-BuPH2 in THF (see below). 

Polymerization was carried out by treating solutions of the monoisocyanates, generally in N,N-dimethylformamide, with catalysts such as sodium cyanide, sodium benzophenone ketyl, sodium naphthalene, or sodium metal. Certain classical anionic reagents such as metal alkyls. 

---