Iron carbonyls coordination

Fe—Fe bond can be assigned structures 201 or 202 based on spectral data. The other product of this reaction is 193 (R = r-Bu), however, it is produced in minor amounts. Complexes 199 (R = R = r-Bu, R = Ph, R = r-Bu) were obtained. Reaction of 146 (M = Mo, R = Ph, R = R = Ft, R = r" = Me) with (benzyli-deneacetone)iron carbonyl gives rise to the bimetallic complex 200 (M = Mo), which reacts further with the free phosphole to form the bimetallic heteronuclear sandwich 203. The preferable coordination of the molybdenum atom to the dienic system of the second phosphole nucleus is rather unusual. The molybdenum atom is believed to have a greater tendency to coordinate via the trivalent phosphorus atom than via the dienic system. 

With the low-valence iron pentacarbonyl, vinylcyclopropanes 22 are thermally transformed to the diene re-complexes, the (1,3-trans-pentadiene)iron carbonyl complexes 23, through bond fission, 1,2-hydrogen shift, and stereoselective coordination [15]. (Scheme 9)... 

The synthesis of metal-coordinated 1-azirines and the reactions of azirines induced by metals have opened a new area in the chemistry of this small ring heterocycle. Many of the reactions encountered bear resemblance to previously discussed thermally and photo-chemically induced reactions of 1-azirines. The reaction of a series of diiron enneacarbonyls in benzene results in coupling and insertion to give diimine complexes and ureadiiron complexes as well as pyrroles and ketones (76CC191). A mechanism for the formation of these products which involves initial 1,3-bond cleavage and generation of a nitrene-iron carbonyl complex as an intermediate was proposed. 

A novel iron carbonyl carbide [Fe5(CO)15C] (41), obtained in small yields from the reaction of dodecacarbonyl iron with pent-l-yne, has been shown to contain a lone penta-coordinated carbon atom surrounded by five iron... 

The kinetics of this reaction have been studied in detail and a hydroxy-carbonyl is specifically proposed as an intermediate consistent with the kinetic data. Decomposition of this intermediate hydroxycarbonyl may proceed by -elimination of the platinum hydride product since the hydroxycarbonyl is a 16-electron coordinatively unsaturated complex. Another well-known example of metal hydride formation from CO and H20 is the reaction of iron carbonyl in aqueous alkali (55) (36). 

If this iron carbonyl hydride is formed by a -elimination from the intermediate (CO)4Fe(COOH)-, a carbonyl must be lost in a prior step since this hydroxycarbonyl is coordinatively saturated. An alternative mechanism would be reductive decarboxylation followed by protonation of the very basic Fe(CO) intermediate. 

Diaza-1,3-butadiene (a-Diimine) Ligands Their Coordination Modes and the Reactivity of Their Metal Complexes, 21, 152 Diene-Iron Carbonyl Complexes, 1, 1... 

Protection and Activation of Alkenes by the Coordination of Iron Carbonyls... 

The resuits obtained from cyclic diazenes and iron carbonyls serve as an example to discuss the modes of coordination of an isolated N=N bond30 62 46 19 As predicted from the electronic structure of these ligands, a-coordination via the orbital is usually favoured over 7T-coordination. Only if the metal is a very good 7r-donor (see Table 8) and the diazene a good jr-acceptor, like azobenzene, will stable 7T-com-plexes be favoured. Thus the first reaction step usually affords the o-N-tetracarbonyl... 

Compounds Derived from Alkynes and Carbonyl Complexes of Cobalt, 12, 323 Conjugate Addition of Grignard Reagents to Aromatic Systems, 1, 221 Coordination of Unsaturated Molecules to Transition Metals, 14, 33 Cyclobutadiene Metal Complexes, 4, 95 Cyclopentadienyl Metal Compounds, 2, 365 Diene-Iron Carbonyl Complexes, 1,1... 

There are a limited number of structures reported for Fe—Pb complexes and these are recorded in Tables 16-18. For a series of iron carbonyl lead clusters, the Fe—Pb bond lengths vary from 2.624 A for an electron-deficient three-coordinate planar Pb cluster [FefCO jjPbl to 2.828 A for a tetrahedral bridging anionic Pb cluster... 

---