Treatment of the dinuclear O-co-ordinated ketene complex W 2 Cp 2 (CO) 5 (µ-η 1 : η 2 -CH 2 CO) (Cp = η 5 -C 5 H 5 ) with PhCH 2 NCS afforded the dark red bridging thioketene complex W 2 Cp 2 (CO) 5 (µ-η 3 -SC᎐ ᎐ CH 2 ). Reaction of the latter with HBF 4 gave the stable cationic product [W 2 Cp 2 (CO) 5 (µ-SCMe 3 )]BF 4 by addition of a proton to the terminal carbon of the thioketene group. In the reaction of W 2 Cp 2 (CO) 5 (µ-η 1 : η 2 -CH 2 CO) with CS 2 cleavage of one CS bond is accompanied by insertion of the resulting sulfur atom into the tungsten-acyl bond to afford W 2 Cp 2 (CO) 5 (CS)-(µ-CH 2 COS). The CpЈ analogue (CpЈ = η 5 -C 5 H 4 Me) was also prepared. The reaction of the trithiocarbonate S᎐ ᎐ C(SCH 2 ) 2 with W 2 Cp 2 (CO) 5 (µ-η 1 : η 2 -CH 2 CO) afforded the carbene complex W 2 Cp 2 (CO) 5 [C(SCH 2 ) 2 ](µ-CH 2 COS), and with allene gave the allylic complex W 2 Cp 2 (CO) 5 (µ-η 1 : η 3 -CH 2 COC 3 H 4 ). Those of the complexes have been characterized by single crystal X-ray diffraction analysis.