Rhenium complexes hydride

Finally, whilst rhenium hydride complexes have not been reported to hydrogenate alkenes, there are several reports of the dehydrogenation of alkanes in the presence of tBuCH=CH2 as an hydrogen acceptor (Scheme 6.14) [136-142]. For example, cycloalkanes are transformed catalytically into the corresponding cyclic alkene, which shows that, in principle, a Re-based catalyst could be designed. 

Reaction of the rhenium hydride complex ReH7(PR3)2 (where R = Ph or p-tol) with Au(PPh3)N03 has yielded the heteronuclear cluster compounds [Au5Re(H)4(PR3)2(PPh3)5](PF6)2 (148) in which the metal cores are based on edge-shared bitetrahedra with the rhenium atom at one of the two most-connected vertices. This is illustrated in Fig. 24. A... 

Synthesis and reactivity of hydrogen-rich uranium-rhenium compounds have been reported. The tris(cyclopenta-dienyl)uranium-rhenium hydride complexes [(CsFI4R)3UF[6Re(PPh3)2] (R=H, Buc, SiMe3) were prepared according to Scheme 87.175... 

ABSTRACT, The rhenium-hydride complexes [ReClH(NCR)(dppe)2][BF4]... 

Fig. 24 Three postulated isomeric rhenium hydride complexes for which formal Re s Re triple bonds were invoked to satisfy the 18-electron nile (right hand side) the corresponding description of their bonding in terms of 3-center-2-electron bonds and direct Re-Re bonds (left hand side)...

In contrast, spectroscopic and crystal structure analysis indicates that nucleophilic attack of hydride on 72 occurs on the face of the ligand which is coordinated to the metal (Scheme 17). No intermediate species could be detected for this latter reaction. Monitoring of the reduction of the rhenium analog 74 with sodium borohydride indicated the intermediacy of a rhenium formyl complex 75, presumably formed by attack on a coordinated carbon monoxide. Signals for 75 eventually disappear and are replaced by those of the (diene)rhenium product 76 (Scheme 18)95. 

Although some hydride complexes have been included in the chemistry of rhenium already described the main discussion of their chemistry is referred to this point due to the ambiguities... 

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