Dimers that Contain Unbridged W(IV)/W(IV) Double Bonds
作者:Lourdes Pia H. Lopez、Richard R. Schrock、Peter Müller
DOI:10.1021/om050961s
日期:2006.4.1
Compounds that contain an unbridged W=W bond can be prepared through bimolecular decomposition of various imido alkylidene complexes. One type of W=W species is [W(NR)(CH2-t-Bu)(OR')](2) (R = 2,6-dimethylphenyl (Ar') or 2,6-diisopropylphenyl (Ar); R' = pentafluorophenyl or hexafluoroisopropyl), which is found in both heterochiral and homochiral forms. The other type is [W(NR)(OR')(2)](2) (R' = trifluoro-tert-butyl or hexafluoro-tert-butyl). All species contain an unbridged W(IV)/W(IV) double bond with a W=W bond distance of 2.4-2.5 angstrom, a 90 degrees angle between the imido ligands and the W=W bond, and an anti relationship of the imido ligands. There is no indication that W=W bonds are broken spontaneously; for example, heterochiral and homochiral [W(NR)(CH2-t-Bu)(OR')](2) species do not interconvert.