Trifluoroacetato Complexes of the d-Transition Metals

The titanium(II) derivatives Ti(02CCFg)X (where X = Cl or Br) have been prepared by the reaction between Ti(02CCF3)2 and the corresponding thionyl halide in ether. All of these titanium(II) trifluoro-acetates are effective as catalysts for the stereospecific polymerization of butadienes (44). 

Four trifluoroacetato complexes of vanadium have been characterized [(7T-Cp)V(02CCF3)2]2 (150), [Mea(stearyl)2N][VCl4(02CCF3)] (20), NH4[V0(02CCF3)3], and V02(02CCF3) (200). The first of these is of the most interest. This compound has a dimeric structure (Fig. 4) with four bridging trifluoroacetato groups but no metal-metal bond 

The known trifluoroacetato complexes of chromium, molybdenum, and tungsten are given in Table V. An X-ray structure determination (52) has shown that Mo2(02CCF3)4 possesses the centrosymmetric structure illustrated in Pig. 5. The Mo—Mo distance of 2.090(4) A is not 

The only trifluoroacetato complex of rhenium that has been prepared is Re(C0)g(02CCF3) 57, 137). The corresponding manganese 

Mn(02CCF3)2 wL (where L = pyandw = 2or4 L = pyridine-A-oxide and n = 1 or L = y-picoline and n = 1, 2, or 4) (7) have been characterized. Compound Mn(acao)2(02CCF3) aids the polymerization of methylmethacrylate and vinyl acetate and is reduced to Mn(acac)-(OgCCFg) in these processes (187, 188). 

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