Complexes with rhenium compounds

Formylation, via bismuth(III) compounds, 9, 440 Formyl complexes with rhenium, G-H BDEs, 1, 300 with tantalum, 5, 162... 

Several rhodium(I) complexes have also been employed as ATRP catalysts, including Wilkinson s catalyst, (177),391 421 422 ancj complex (178).423 However, polymerizations with both compounds are not as well-controlled as the examples discussed above. In conjunction with an alkyl iodide initiator, the rhenium(V) complex (179) has been used to polymerize styrene in a living manner (Mw/Mn< 1.2).389 At 100 °C this catalyst is significantly faster than (160), and remains active even at 30 °C. A rhenium(I) catalyst has also been reported (180) which polymerizes MM A and styrene at 50 °C in 1,2-dichloroethane.424... 

Low and medium oxidation states like 0, -l-I, -fII, and -fill seem to be stabilized best by NHCs. Difficulties in preparing and isolating the desired compounds occur with higher and lower oxidation states, although extreme cases such as complexes of rhenium(VII) are known. In summary, almost every transition metal has been used to prepare NHC complexes by one of the routes described previously. 

Rhenium(VI) nitride compounds can be generated by oxidation of rhenium(VI) complexes with chlorine or bromine. The products formed are often unstable and ligand exchange reactions with CP or Br lead to a complex mixture of Re compounds. Oxidation of the rhenium(V) complex [ReN(PPh3)Cl(cpCo PO(OR)2 3)] with Ag(BF4), however, yields [ReN(PPh3)Cl(cpCo- P0(0R)2)3)](BF4) (53) in good yields. ... 

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