Sodium tetracarbonylferrate reduction

Disodium tetracarbonylferrate (Collman s reagent) is prepared by the reduction of Fe(CO)5 with sodium naphthalene in THF or sodium benzophenone ketyl in dioxane. Though it can be isolated as a white precipitate, it is usually used in THF or dioxane solution without isolation because of its highly air-sensitive and pyrophoric character. It is reported that the solubility of Na2[Fe(CO)4] is 7 x 10 M in THF and that it can be stored for moderate periods in an inert atmosphere in the dark [36]. X-ray crystallography of Na2[Fe(CO)4] (Fig. 10.2) shows that the C—Fe—C bond angle opposite to the sodium cations is significantly distorted (129.7°) [37]. However, this distortion is reduced for the potassium analogue [38]. 

Methoxy(aryl)carbene]iron complexes are obtained by reaction of the appropriate benzoic chlorides with [Fe(C5Mes)(CO)2]K to give the acyliron complexes, followed by methylation with methyl mesylate. Reduction with sodium borohydride and removal of the methoxy group by treatment with trimethylsilyl triflate affords the defunctionalized (arylcarbene)iron complexes. The presence of ortAo-methoxy or ortho-chloro substituents at the arene moiety gives rise to (T) -C,OMe) or (T1 -C,C1) chelate (arylcarbene)iron complexes upon irradiation. Disodium tetracarbonylferrate reacts with aromatic (V,A -diallylamides followed by treatment with trimethylsilyl chloride with direct formation of chelated a-aminocarbene complexes (Scheme 4-59). ... 

---