Iron hydrido complex anion

The electrochemical reduction of a series of cationic iron(II) hydrido complexes trans-[FeH(L)(dppe)2]+ (L = N2, C5H5N, PhCN, CH CHCN, MeCN, P(OMe)3, P(OEt)3, CO) has been shown to proceed via transient d1 iron(I) species which lose one of the neutral ligands. Further reduction of the resulting five-coordinate intermediates yields stable rf8 iron(O) anionic hydrides.233... 

The reductive dehalogenation of haloalkanes has also been achieved in high yield using polymer supported hydridoiron tetracarbonyl anion (Table 11.15). In reactions where the structure of the alkyl group is such that anionic cleavage is not favoured, carbonylation of the intermediate alkyl(hydrido)iron complex produces an aldehyde (see Chapter 8) [3]. 

It is deduced from infrared data (206) that iron pentacarbonyl reacts with bromine at — 80° C to form the cationic halogeno carbonyl [Fe(CO)sBr]+Br (206), and the covalent Br—CO—Fe(CO)4Br. From similar infrared data, however, it is concluded that the product is a seven-coordinate non-ionic complex Fe(CO)5Br2 (76) The reaction of Os(CO)3(PPh3)2 with hydrogen chloride produces a cationic hydrido carbonyl, which may be isolated, although it readily reverts to a neutral dichloride by attack of the associated chloride anion (52). 

The reaction of sodium hydroxide with iron pentacarbonyl results in a nucleophilic attack by a hydroxide ion on the carbonyl group to give a metal carboxyHc add complex. Upon further action with sodium hydroxide, the carboxyHc add gives up carbon dioxide to form a hydrido anion. The protonation of this anion results in the formation of iron tet-racarbonyl hydride (Fleiber base) as... 

Similar to reactions with arsenic selenide anions described in the previous section, pentacarbonyliron or the hydrido-iron tetracarbonyl anion react with arsenic tellurides to produce complex iron carbonyl-bound tellurium arsenic anions (Scheme 85). Unlike the selenium analogs, the isolated complex for Te does not exhibit Fe-As bonds. 

---