Rhenium, thiolate complexes

A major group of rhenium(II) complexes is characterized by two chelating bis-phosphines forming the equatorial plane of a distorted octahedron (263). The axial ligands can be varied and representatives with halides, pseudohalides, thiolates, and nitriles have been studied extensively. 

Oxidation of rhenium(I) species has also been observed during reactions of [ReCl(N2)(dppe)2] with thiolates which gives [ReCl(SR)(dppe)2] (R = C6H4-4-Me), " or [ReCl(NCR)(dppe)2] with electrophiles. Whereas the latter type of reactions with [Et20H][BF4] or TMSCF3SO3 lead to the formation of methylenamide rhenium(I) complexes which will be treated more in detail in Section 5.3.2.7.2(i),... 

S. Cai, D. M. Hoffman, and D. A. Wierda, Alkoxide and Thiolate Rhenium(VII) Oxo-Alkyl Complexes and Re205(CH2CMe3)4, a Compound with a [02Re—O—Re02]4+ Core, Inorg. Chem. 28, 3784-3786 (1989). 

It is clear that electron-withdrawing alkoxides in M(NAr)(CHR)(OR )2 complexes dramatically increase the rate of reaction of an olefin with the M=CHR bond. In fact, no other X ligands in M(NAr)(CHR)X2 complexes are as successful as alkoxides for sustained metathesis activity, [66] either because they are not bulky enough to stabilize an electron deficient metal center and prevent bimolecular decomposition (e.g., halides) or because they donate too much electron density to the metal in a a and/or Ji fashion (e.g., amides or thiolates). A recent example is Mo(NAr)(CHR)(diamide) where the diamide is a N,N -disubstituted-2,2 -bisamido-l,r-binaphthyl ligand no ready reaction was observed between this complex and ethylene or even benzaldehyde. [108] Alkylidene complexes are now known for all metals in groups 4, 5, and 6, plus rhenium. For example, it was shown that Cp2Ti(CH2) could be trapped... 

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