Iron carbonyl hydride preparation

Iron carbonyl hydrides, preparation and properties, 6, 7 Iron cations, acyclic (rj5-pentadienyl) Fe, 6, 153-154 Iron clusters... 

The mercury compounds HgFe(CO)4 and Fe(CO)4(HgX)2 (X = C1, Br, I), which were the first representatives of non-ionic metal derivatives of iron carbonyl hydrides, were discovered by Hock and Stuhlmann (V, 36). During investigations into the preparation of cobalt carbonyls from cobalt halides under CO pressure, in the presence of another metal as a halogen acceptor, we discovered the mixed metal carbonyls M[Co(CO)4]2 (M = Zn, Cd, Hg, Sn) and M[Co(CO)4]3 (M = In, Tl) (44), e.g.,... 

The analogous cycloheptadienyl complex (5 equation 1) was similarly prepared by Dauben and Ber-telli,4 but the acyclic pentadienyl systems were a little more difficult to obtain. The triphenylmethyl cation does not remove hydride from tricarbonyl(frans-pentadiene)iron (6 equation 2). The corresponding c/s-pentadiene complex (7 equation 3) cannot be prepared directly from the diene and an iron carbonyl,... 

The first known complex in this class, frans-bis(triethylphosphine)-platinum chlorohydride, was prepared by Chatt and co-workers (86). In the light of other hydrides known at that time, in particular the carbonyl hydrides of iron and cobalt and bis(7r-cyclopentadienyl)rhenium hydride, the great stability of this complex was quite unique. It rapidly became clear that tertiary phosphine ligands were markedly effective in stabilizing the metal-hydrogen bond, and ligands such as PhjP, EtjP, o-CaH PlVfe, ... 

All the simple carbonyl hydrides (Table IY) may be readily prepared by acidification of alkali metal salts derived from the simple carbonyls. Only the carbonyl hydrides of Mn, Re, Co, and Fe are well characterized. They form highly toxic volatile liquids and are unstable thermally and with respect to oxidation. Pentacarbonylmanganese hydride is stable to light and air for several hours at room temperature (173), while the very unstable cobalt and iron complexes decompose spontaneously at — 20°C (167, 251). It may be noted that solutions of these carbonyl hydrides in inert solvents undergo spontaneous decomposition much more slowly than the pure substances. 

A hydride is one of the simplest nucleophiles, and Casey ° and Gladysz have prepared kinetically stable formyl complexes by the direct attack of hydride on a number of neutral chromium-, molybdenum-, and iron-carbonyl complexes (Equation 11.2). Although these complexes are relatively electron rich, because they possess zero-valent metal centers, the negative charge in the product can be stabilized by the remaining -ir-ac-cepting CO ligands. 

Cyclododecene may be prepared from 1,5,9-cyclododecatriene by the catalytic reduction with Raney nickel and hydrogen diluted with nitrogen, with nickel sulfide on alumina, with cobalt, iron, or nickel in the presence of thiophene, with palladium on charcoal, with palladimn chloride in the presence of water, with palladium on barium sulfate, with cobalt acetate in the presence of cobalt carbonyl, and with cobalt carbonyl and tri- -butyl phosphine. It may also be obtained from the triene by reduction with lithium and ethylamine, by disproportionation, - by epoxidation followed by isomerization to a ketone and WoliT-Kishner reduction, and from cyclododecanone by the reaction of its hydrazone with sodium hydride. ... 

Ill) Iron and Ruthenium. w-Allyliron complexes are not readily prepared directly from olefins by cleavage of an allylic C—H bond, but Jt-allylhydridoiron complexes are intermediates in olefin isomerization catalyzed by Fe(0) carbonyl complexes ". The intermediate 7i-allyliron hydride complexes formed are too reactive to be isolated and undergo a fast reductive elimination to give the isomerized or the starting olefin ... 

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