Heterobimetallics Fe

A number of transition metal complexes will catalyze the dehydrogenative coupling of organotin tin hydrides, R SnI I, to give the distannanes, RjSnSnRj.443 These metals include palladium,449 gold,450, hafnium,451 yttrium, and ruthenium.452 The catalyst that is most commonly used is palladium, often as Pd(PPh3>4, and the most active catalysts appear to be the heterobimetallic Fe/Pd complexes, in which both metals are believed to be involved in the catalysis.443... 

CO-, Isonitrile-, and Phosphine-induced Silyl Migration Reactions in Heterobimetallic Fe-Pd and Fe-Pt Complexes... 

Scheme 20 Ethylene polymerization with heterobimetallic Fe/Zr complexes...

Scheme 21 Catalytic dehydrogenation of amine boranes by a heterobimetallic Fe/Zr complex...

The synthesis of Fe-Mo and Fe-W dinuclear complexes is often assisted by bridging phosphido ligands, although it is also known that a number of tungsten acetylides " and related complexes " provide effective building blocks for the creation of heterobimetallic Fe-W complexes. 

The monodentate dppm complex [Fe(77" -MeC5H5)(77 -dppm)(GO)2] 31 reacted with [Rh(GO)2Gl]2 in THF/ //-hexane at room temperature (RT) to give a novel heterobimetallic Fe-Rh complex 32. ... 

Closely related heterobimetallic Fe-Pd and Fe-Pt complexes that are bridged by the PR2 group instead of bidentate phosphine chelates were also reported by Braunstein. " It is interesting to note that novel intramolecular metal-to-metal silyl ligand migration reaction on these phosphido-bridged Fe-Pt complexes can be effected by the... 

These heterobimetallic M -M -binol complexes consdnite a new class of v/idely applicable chiral catidysts as shown in Scheme 3.16. The new catidysts consist of a centtidmetid ion fe.g.. La" , AT , Sin , Ga , three alkali inetid ions fe.g., LT, Na , K l, and three chirid tliphenol... 

Thiolate-bridged dinickel complexes and, in particular, heterobimetallic Ni/Fe complexes have attracted much interest as model systems for the hydrogenase enzymes. A review covering this... 

In the case of the heterobimetallic systems, the few examples known so far are [ClPt(p-dppm)2(p-C=N-Me)Ni(CNMe)]Cl (64), reported by Kubiak and collaborators, which is obtained via a transmetallation of [(CNMe)]Ni (p,-dppm)2(p,-C = N-Me)Ni(CNMe)] with [Pt(dppm)Cl2].80 The other examples are the mixed M-Pt systems 65—74 (M = W, Fe, Mo, Cr) containing a dis-phosphine backbone (dppm or dppa), as described by Knorr and collaborators81 -84 (Fig. 31). These complexes were obtained via substitution of the bridging carbonyl by an isocyanide ligand. 

Finally, we reported a di-iron(III) catalyst 24 and the corresponding copolymerization activity [147]. This system was able to produce copolymer with CHO/C02 and demonstrated a TOF of 53 h 1, at 80°C, lObar and aCHO/Fe ratio of 10,000 1. The system did not yield copolymer with PO, but addition of one equivalent of [PPN]C1, per Fe centre, allowed the conversion of PO into cyclic propylene carbonate with TOFs around 10 h 1. Previously, some heterobimetallic iron tert-butoxide complexes ( (7-BuO)5FeLa] and [(f-BuO)4FeZn]) had been reported for the copolymerization of PO and C02 [153]. This catalyst was the first use of an iron complex for the homogeneous copolymerization of CHO and C02. Rieger and coworkers recently reported a mononuclear Fe system that showed similar behaviour towards PO [154] and some copolymer formation with CHO/C02 strongly dependent on the co-catalyst system [98]. 

The Pt—Fe heterobimetallic complex 33 reacts reversibly with 30 to form 34, containing both terminal and bridging germylene ligands (equation 37)144. 

A heterobimetallic polycarbostannane 64142 was obtained from the reaction of the bidentate [Fe(CO)2Cp-X-Cp(CO)2Fe]2- (X = -CHNMe2CHNMe2-) with Ph2SnCl2. The molecular weight as determined by osmometry was Mn = 8.5 x 1()3 gmol-1, indicating relatively short chains. The reaction of the methylene-substituted dianionic... 

Zhu W, Marr AC, Wang Q, et al. Modulation of the electronic structure and the Ni-Fe distance in heterobimetallic models for the active site in [NiFeJhydrogenase. Proc Natl Acad Sci USA. 2005 102(51) 18280-5. 

This reaction was first reported in the early 1970s as an unexpected result in search for the synthesis of new organometallic cobalt complexes [13-18]. Dicobalt octacarbonyl was the only cluster used in its beginnings, although now, many cobalt species and other metal complexes are able to mediate or catalyze this reaction. Thus, the stoichiometric reaction has been performed with Zr, Ni, Fe, Ti, W and Mo derivatives. In addition, heterobimetallic Co - W and Co - Mo complexes (1), are suitable precursors for the PKR and impart a high degree of selectivity in the process giving exclusively endo adducts 2 (Scheme 2) [19,20]. 

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