Iron and ruthenium

The only known organo-a-iron complex in this class is the golden-yellow trans-(Et2PhP)2Fe(C6Cls)2, m.p. 135-142 [47]. Attempts to prepare related alkyl complexes were unsuccessful, presumably due to the low thermal stability expected for such complexes. The stability of the complexes (PR3)2M(orr -aryl)2 falls markedly in the order Ni Co Fe. 

Treatment of the octahedral ruthenium(Il) chloride (P— P)2RuQ2, where P—P = Me2PCH2CH2PMe2, with arylsodium gives complexes of stoicheiometry Ru(arene)(P— P)2, where arene = benzene, naphthalene, anthracene and phenanthrene [22]. Detailed chemical infrared and proton magnetic resonance studies have shown that the compound in solution is an equilibrium mixture of the arene complex and the a-aryl hydride complex, e.g. 

Pyrolysis of Ru(arene)(P—P)2 gives a compound which shows a similar equilibrium, viz. 

These ruthenium complexes are most unusual and interesting, and provide an excellent example of the ease with which a transition metal may abstract a hydrogen which is attached to a carbon in a -position (see 

---

After the completion of this manuscript a paper concerning conformational analyses of 1,1, 3,3 -tetra-r< H-alkylmctallocene of iron and ruthenium including 6 based on thorough NMR spectroscopic measurements (line-shape analysis) has appeared in which the nature of the transition states has conclusively been discussed in detail [164]. 

The moments of complexes containing NO offer a puzzling problem. The diamagnetism of compounds of iron and ruthenium suggests that Feiv and RuIV form a double bond with NO, making seven bonds in all, which woud lead to /t = 0. But this structure cannot be applied to [Co(NH3)6-NO]Cl2, which has a moment corresponding to a triplet state. Further study of such complexes is needed. 

Kiindig EP, Saudan CM, Viton F (2001) Chiral cyclopentadienyl-iron and -ruthenium Lewis acids containing the electron-poor BIPHOP-F ligand a comparison as catalysts in an asymmetric Diels-Alder reaction. Adv Synth Catal 343 51-56... 

Viton F, Bemardinelli G, Kiindig EP (2002) Iron and ruthenium Lewis acid catalyzed asymmetric 1,3-dipolar cycloaddition reactions between nitrones and enals. J Am Chem Soc 124 4968-4969... 

As a continued effort to prepared hexameric systems based on the self-assembly of directed bw-terpyridine monomers, several interesting in families, e.g. 43, of iron and ruthenium connectivity have appeared <06DMP413, 06DT3518>. But in the assembly process, the creation of a three-step procedure to the novel first nondendritic fractal 44 entitled the "Sierpinski hexagonal gasket" was reported <06MI1782>. 

FIGURE 9.7 Operating ranges of the catalysts nickel, cobalt, iron, and ruthenium in FT synthesis as indicated by Pichler. 

Barrau and coworkers have synthesized a series of iron and ruthenium complexes by irradiation of Me2HGe(CH)KGeMe2H and Me2HGe(CH)K SiMe2H (n = 1, 2) in the presence of Fe(CO)5 and Ru3(CO)i293. In each case irradiation causes CO loss, with the formation of the M(CO)4 species (reaction 43). When n = 2 the products are photostable with n = 1 (65) a mixture of products (66-69) are obtained due to secondary photolysis (reaction 44). The mechanism, outlined in Scheme 23, is presented to explain these observations. 

DR. SUTIN The cobalt systems that you mention differ from the iron and ruthenium systems I discussed in that the electron transfer is also accompanied by a spin change the cobalt(III) complexes are low-spin and the cobalt(II) complexes are high-spin. Thus, the electron transfer is spin forbidden and should not occur since =0. It becomes allowed through... 

In 2002, Kiindig et al. [23, 24] developed catalytic DCR between diaryl nitrones and a,(3-unsaturated aldehydes in the presence of Binop-F iron and ruthenium complexes as chiral Lewis-acid catalysts (Scheme 6). The corresponding cycloadducts were obtained in good yields with complete endo selectivity and up to 94% ee. The isoxazolidine products were obtained as a mixture of regioi-somers in molar ratios varying from 96 4 to 15 85. Experimental and computational data show that the regioselectivity correlates directly with the electronic properties of the nitrone. 

Reactions of bis(dimethylgermylethane-iron and -ruthenium tetracarbonyls with o-quinones probably undergo a SET process to give eight-membered digermylated dioxocanes <90IC1674, 91JOM(406)123>. 

Dynamic kinetic resolution is an excellent methodology to prepare enantiomeri-cally pure compounds and, in this context, chiral 4-(dimethylammo)pyridine (DMAP) iron and ruthenium " complexes have been reported to catalyze the... 

X-VlNYLIDENE MANGANESE, IRON, AND RUTHENIUM COMPLEXES AND Geometrically Related Molecules (X-Ray Diffraction Data)... 

Similar reactions are found with the iron and ruthenium complexes in which the metal-metal bonds are also bridged by //-CO or //-CMe2 groups (65, 66, 68) ... 

These iron and ruthenium dimers are exceedingly robust compounds. Indeed decomposition of trinuclear phosphidoacetylide-bridged clusters invariably yields these molecules as major decomposition products ... 

The linkage of transition metals to skeletal phosphorus in a phosphazene has presented an unresolved challenge for many years. We have recently succeeded in the preparation of iron and ruthenium phosphazenes by the reaction shown below (8). 

---