Iron carbonyls, binuclear

P-31 Chemical Shift-Bond Angle Correlations in Binuclear Iron Carbonyls... 

As alluded to earlier, we have amassed a large body of X-ray data for binuclear iron carbonyl complexes of the Fe2(CO)6(X)(PPh2) type where X represents a three-electron donor ligand. The P-31 chemical shifts for these compounds are tabulated with Fe-P-Fe angles in Table III and a plot of 8 vs. angle is shown in Figure 11. Although the correlation is by no means perfect there is an unmistakable increase in... 

In 1980 we published a survey (1) of our major results in this area as of late 1979. These results include extensive work on binuclear CF N PF complexes of cobalt (2,3,4,5) and nickel (6). This paper summarizes our more recent results in this area with particular emphasis on binuclear complexes of chromium, molybdenum, and tungsten as well as some new results on iron carbonyl derivatives. 

Iron carbonyl complexes are easily prepared by the reaction of Fe2(CO)9 with a cyclic diazene. An excess of the diazene prevents the more favoured formation of binuclear compounds29 3°). Trans-diazenes like trans-dimethyldiazene3 or azo-... 

The mass spectra of some binuclear iron carbonyl complexes of the type (triene) Fe2(CO)g have been investigated 26>33b Reaction between... 

The mass spectra of binuclear iron carbonyl complexes of acenaphthylene and azulene have been briefly reported 26). The acenaphthylene complex previously 43> reported as Ci2H8Fe2(CO)6 exhibits Ci2H8Fe2 (CO)5 as the highest m/e ion the implied pentacarbonyl formulation was later 44> confirmed by X-ray crystallography which indicated structure 16. The reaction between azulene and Fe(CO)s has been reported 45> to give dark red CioHgFegfCOJs this formulation was confirmed by... 

My co-worker H. Beutner (95) was able to isolate from a nitrite-containing carbonylferrate solution, in trace amounts only, a binuclear nitrogen-atom-bridged iron carbonyl compound. This complex is now obtained in good yield by UV irradiation of the reaction solution and was identified mass spectrometrically as di-/x-amino-bis(tricarbonyl)iron, (OC)3Fe(NH2)2Fe (C0)3. The group... 

Cyclic diazo compounds are known to form mononuclear cr-complexes with iron carbonyl compounds, which further react to give more stable binuclear complexes containing an Fe-Fe bond <1976TCC105>. However, such complexes are rare in the case of cyclic four-membered diazo compounds. No new examples have been reported in the last decade. For more informations, CHEC-II(1996) should be consulted <1996CHEC-II(1B)911>. 

When iron carbonyl complex 106 was treated with 1 equiv of [Fe2(CO)9], the binuclear complex 161 was isolated as red crystals in 42% yield. This complexation was accompanied by the cleavage of the P-P bond. 

Of considerably greater interest is 77-allyl ligand transfer from one metal to another. Although the examples of such reactions are rather few they have been studied in detail. The first example of a 7r-allyl ligand transfer from one metal to another was reported by Nesmeyanov, Rubezhov, and Gubin (156). Iron carbonyls were found to react with some substituted binuclear 77-allylpalladium halides in benzene at room temperature, giving the respective 77-allyliron derivatives ... 

The photochemistry of the binuclear iron carbonyl [( -CsHslFe-(CO)2]a, VIII, provides another outstanding example of the interplay between time-resolved and alternative strategies (76). According to the infrared spectrum of this compound in a suitable matrix at low temperatures (83), ultraviolet photolysis results in the elimination of free CO, but the pronounced cage effect of the medium entirely sup-... 

No less striking have been the advances made in our understanding of the substitution reactions peculiar to the much studied binuclear iron carbonyl, VIII (83-85). Here, too, a variety of experimental techniques has been brought to bear on the intermediate photoproducts— one a binuclear species IX and the other a mononuclear radical X— which differ hugely in their reactivity. 

Some interesting organosulfur derivatives of iron carbonyls can be obtained by reactions of Fe3(CO)i2 Normally reactions of thiols (RSH) or disulfides (RSSR) with Fe3(CO)i2 give red, air-stable binuclear derivatives of the type [RSFe (CO) 3] 2 (dls M = Fe) with complete rupture of the iron triangle (193). However, stoichiometric quantities of Fe3(CO)j2 a secondary alkyl thiol react to form trinuclear deriva-... 

The w-(C4)M system has also been observed in ring systems in which a father simpler situation from the spectroscopic viewpoint exists than in the parent olefin. Two such examples are the complexes of cyclopentadienone (XXI) or the unusual binuclear complex obtained from an iron carbonyl and acetylene, C4H4- Fe2(CO)6 (XXII) (Table XV). The proton resonances in these complexes may be analysed simply as A2B2 systems. Details on the structures, especially the position of the protons in these complexes, is not yet known. 

Cyclopentadiene and its derivatives react in an unusual manner with iron carbonyls. Reaction of cyclopentadiene with Fe(CO)s under conditions normal for the preparation of diene-iron tricarbonyl complexes produces the binuclear complex (XLIV) and cyclopentene rather than (XLV) (69, 70). 

Thiophene has been reported to react with Fe(CO)s to produce a material described as thiophene-iron dicarbonyl 52). However, a complex having very similar properties to this substance and also obtained from the reaction of thiophene and Fe(CO)s or Fe3(CO)i2 was found not to contain sulfur (74) and the existence of thiophene-iron dicarbonyl is questionable. The material which does not contain sulfur is found to be identical to one of the products obtained upon reaction of acetylene with iron carbonyl, for which the binuclear structure (LVIII) has been proposed 38, 54, 75). 

A. Mono- and Binuclear Complexes from Metal Carbonyls 1. Iron... 

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