The molybdenum and tungsten complexes M 2 (OR) 6 (Mo2F6, M= Mo, R= C (CF 3) 2 Me; W2F3, M= W, R= OC (CF 3) Me 2) were synthesized as bimetallic congeners of the highly active alkyne metathesis catalysts [MesC≡ M {OC (CF 3) n Me 3− n}](MoF6, M= Mo, n= 2; WF3, M= W, n= 1; Mes= 2, 4, 6-trimethylphenyl). The corresponding benzylidyne complex [PhC≡ W {OC (CF 3) Me 2}](W Ph F3) was prepared by cleaving the W≡ W bond in W2F3 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 W2F3 and the alkylidyne complex W Ph F3. In contrast, Mo2F6 displayed no significant activity in alkyne metathesis.