“…Indeed, prior to our recent report of the compounds RHgC"CCF 3 (R = Me, n-Bu, t-Bu, Ph, Fc) [1] only seven such materials were known, viz. : Hg(C"CCF 3 ) 2 [9,10], Hg(CF@CF 2 ) 2 [11], BrHg(CF@CF 2 ) [11a,11b], Hg(C(CF 3 )@CF 2 ) 2 [12], ClHg(CF@CF 2 ) [13], Hg(CCl@CF 2 ) 2 [13], ClHg(CCl-@CF 2 ) [13] and (CH 2 @CH)Hg(CF@CF 2 ) [14], most of which are prepared using Grignard or organolithium reagents. Of these only two, ClHg(CF@CF 2 ) [13] and Hg(CF@CF 2 ) 2 [15], have been structurally characterised.…”