The acylcobalt tetracarbonyls [RC(O)Co(CO)(4)] (1) undergo self-acylation i
n the presence of nBu(4)NI, in toluene at room temp., to yield the dinuclea
r mu (2)-acylhydroxycarbene-type complexes [{RC(O)}(2)Co-2(CO)(6)] (2). Com
plex 2, with R = tBu, was also characterised by X-ray diffraction.