Efficient catalytic alkyne metathesis with a fluoroalkoxy-supported ditungsten(III) complex.

The molybdenum and tungsten complexes M(OR) (, M = Mo, R = C(CF)Me; , M = W, R = OC(CF)Me) were synthesized as bimetallic congeners of the highly active alkyne metathesis catalysts [MesC≡M{OC(CF) Me }] (, M = Mo, = 2; , M = W, = 1; Mes = 2,4,6-trimethylphenyl). The corresponding benzylidyne complex [PhC≡W{OC(CF)Me}] ( ) was prepared by cleaving the W≡W bond in with 1-phenyl-1-propyne. The catalytic alkyne metathesis activity of these metal complexes was determined in the self-metathesis, ring-closing alkyne metathesis and cross-metathesis of internal and terminal alkynes, revealing an almost equally high metathesis activity for the bimetallic tungsten complex and the alkylidyne complex . In contrast, displayed no significant activity in alkyne metathesis.