Trinuclear iron

Thermal ST occurs in the trinuclear iron(II) complex [Fe3(iptrz)6(H20)6](Trifl)6 (with iptrz = 4-isopropyl-1,2,4-triazole and Trifl = trifluoromethanesulfonate) only at the... 

The first signs of this spin richness are seen in the magnetism of the trinuclear iron-sulfur cluster [3Fe-4S], a distorted cube of alternating Fe and S comers from which one Fe has been removed. In the fully oxidized state, [3Fe-4S]1+ all three iron... 

The black trinuclear iron complex Fe3(CO)8(Ph2C2)2> one of two isomers obtained by the reaction of excess tolane with dodecacarbonyl iron, contains not only a heterocyclic iron atom similar to that first observed by Hock and Mills (36) but also has two iron atoms lying symmetrically on either side of the heterocyclic ring (42) in a manner similar to that suggested by the author on theoretical grounds (20) (Fig. 9). 

Among the sulfur-bridged trinuclear iron carbonyls S2Fe3(CO)g (structure like [25]) has been prepared in a new way (52), and CO substitutions of this (52) and the... 

Te were isolated. Their structures [2S] (366, 368) are similar to those of the ECo3(CO)9 clusters [27] and thus offer the possibility for the experimental bonding investigation mentioned in Chapter 2.3. Of SFeCo2(CO)9CO substitutions by isonitriles have been observed (304). Other trinuclear iron-cobalt clusters include CpCoFe2(CO)9 obtained from CpCo(CO)2 and Fe2(CO)9, for which structure [92] was made plausible (272), and CpFeCo2(CO)g(C=CPh), for which structure [94] was suggested (403). 

In 1993, Murai s group examined the effectiveness of the iron-triad carbonyl complexes Fe(CO)5, Fe2(CO)9 and Fe3(CO)12 as catalysts for the reaction of styrene with triethylsilane [47]. Whereas Fe(CO)5 showed no catalytic activity, Fe2(CO)9 and Fe3(CO)12 formed selectively P-silylstyrene 57a and ethylbenzene 58. Interestingly, Fe3(CO)12 is the catalyst that exhibited the highest selectivity. This trinuclear iron carbonyl catalyst was also successfully applied in the reaction of different para-substituted styrenes with Et3SiH giving only the (E)-P-triethylstyrenes in 66-70% yield (Scheme 4.23). 

The first experiments which were carried out in the author s laboratory on organometallic phase-transfer catalysis were concerned with the reduction of nitrobenzenes (4) to anilines (5) by triiron dodecacarbonyl. Such a conversion was reported to occur in benzene containing methanol at reflux for 10-17 h, with the hydridoundecacarbonyltriferrate anion as the likely key intermediate (16). It was our expectation that the trinuclear iron hydride should be generated by phase-transfer catalysis and if so, effect reduction of nitro compounds (4) under exceedingly mild conditions. Indeed this was the case, as illustrated by the results shown in Table I (17). Not only is the reaction complete in 2 h or less using sodium hydroxide as the aqueous phase, benzene as the organic phase, and benzyltrieth-ylammonium chloride as the phase-transfer catalyst, but it occurs at room temperature and requires less metal carbonyl than when the reaction was... 

A stable trinuclear iron cluster 188 in which an allenyl unit is bonded in a /x3—T73 fashion has been derived from compound la by transmetallation... 

Scheme 78. Trinuclear iron derivative of an alkoxy(l-alkynyl)carbene complex.

Scheme 7-11 shows the molecular assemblies of a few dinuclear and trinuclear iron(ii) clathrochelate complexes linked to a ferrocenylboronic or a l,l -ferrocenyl-diboronic fragment, which have been recently prepared [82]. 

Electrochemical characteristics (mV, vs Fc+/Fc) of ferrocenylboron-capped trinuclear iron(II) clathrochelates [66]. 

Reaction of Fe(CO)5 with cyclo-(AsMe)5 yielded the dimer [Fe(CO)3]2[p, j -catena (MeAs)4] with a four-membered AsMe chain . The trinuclear iron cluster [Fe(CO)3]3[SbCH(SiMe3)2]2 contains an antimony ligand. The Sb atoms are bound to each other, secondly to the organo group and thirdly coordinated to three Fe atoms each . p3-SbR ligands are rare. However, recently a species of the type [HFe3(CO)9 (p3-SbBu )] [PPN] has been reported . 

Whereas trinuclear iron clusters have been used in stoichiometric reduction of aromatic nitro compounds, the tetranuclear iron cluster Cp4Fe4(CO)4 can be used for the catalytic hydrogenation of nitrobenzene to aniline [Table IV (92,96,113-116)]. 

According to the X-ray crystallographic analysis, 30 is present in the crystal as a neutral, trinuclear, iron chelate complex (Figure 19, right 3D-4). The core of... 

The spectra of five trinuclear iron(III) carboxylate complexes of the type [Fe3(RC02)6(OH)2]X.xH20 are consistent with high-spin iron(III) in a dis-... 

The first studies on the interactions between trinuclear iron carbonyl clusters and thiols were reported by DeBeer and Haines. " Secondary alkanethiols RSH [R = Pr, Bu ] were reacted with [Fe3(CO)i2] under reflux in benzene with the aim of synthesizing [Fe(CO)3(SR)]2. In addition to the desired product, new tri- and tetranuclear sulfido-bridged derivatives of [Fe3(CO)i2] were isolated. Initially, [Fe3(CO)9(/r-H)(//3-SR)] was obtained. The corresponding reaction involving Bu SH similarly afforded [Fe3(CO)9( -H)(//3-SBu )j (7). Prolonged heating of a benzene solution of this thiol and [Fe3(CO)i2] yielded four... 

This technique was used to resolve trinuclear iron complexes by using sephadex SP-C25 as the stationary phase and an aqueous solution of (+)-tartratoantimonate (111) as eluant.t °° ... 

For [Fe3(CO)i2], considerable asymmetry of the bridging Fe —CO —Fe bonds is characteristic. In solutions, this trinuclear iron compound exhibits dynamic properties. The IR spectra show that the number of isomers with bridging carbonyl groups... 

Several trinuclear iron carbonyl clusters have been subjected to a Fenske-Hall MO treatment by Buhl and co-workers. Hall has released details of the methodology for calculating potential energy surfaces for carbonyls, phosphines etc. using a variety of electron correlation techniques. 

In some cases more detailed information is available for the trinuclear iron clusters containing nine and ten carbonyl ligands in Organoiron Compounds C 6a, 1991, pp. 295/300 and Organoiron Compounds C 6b, 1992, pp. 69/71, respectively, and for the tetra-nuclear iron species in Organoiron Compounds C 7, 1986, p. 237. 

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