MERCURY-OSMIUM CARBONYL CLUSTERS RESULTING FROM FACILE HG-C BOND-CLEAVAGE - REACTIONS OF [OS3H2(CO)(10)] WITH [HG(C CPH)(2)] AND [RHGC CHGR] (R=PH, ME OR ET)

Reaction of the unsaturated cluster [Os3H2(CO)(10)] with Hg (C=CPH)(2) afforded two new Os-Hg clusters CO)(4){(mu-Hg)Os-3(CO)(10)(mu-eta(2)- CH=CHPH)}(2)] 1 and [{Os-3(CO)(10)(mu-eta(2)-CH=CHPH)}(2)(mu(4)-Hg)] 2 in 30 and 20% yield, respectively. Cluster 1 consists of two (mu-Hg)O s-3(CO)(10)(mu-eta(2)-CH=CHPH) subunits bonded to a central Os(CO)(4) moiety in the cis configuration which under ambient conditions convert s into 2 over 3-5 d with the extrusion of a HgOs(CO)(4) unit. Cluster 2 comprises two skewed Os-Hg metal butterflies sharing a common wingti p Hg atom. In refluxing tetrahydrofuran (66 degrees C) 2 underwent red istribution with the symmetrical mercurials [Hg{M(CO)(3)(eta(5)-C5H5)} (2)] (M = Cr, Mo or W) to afford respectively the heterometallic clust ers eta(2)-CH=CHph)}(mu(3)-Hg){M(CO)(3)(eta(5)-C5H5)}] (M = Cr 3, Mo 4 or W 5) in moderate yield. Alternatively, 3-5 can be obtained more re adily from the reaction of cluster 1 with the corresponding symmetric mercurials at room temperature. Reactions of [Os3H2(CO)(10)] with [RHg C=CHgR] (R = Ph, Me or Et) afforded the clusters )(10)(mu-eta(2)-CH=CH 2)}(mu(4)-Hg)(CO)(10)(mu-H)}] 6 (12%) and [{Os-3(CO)(10)(mu-eta(2)-CH= CH2)}(2)(mu(4)-Hg)] 7 (25%). Cluster 7 is isostructural with 2, whilst 6 bears a central Hg atom connecting two structurally different osmiu m triangles. Clusters 1, 2, 6 and 7 all result from Hg-C bond cleavage of the parent organomercury species, hence the generality of this cle avage is demonstrated. The new clusters 1, 2, 4, 6 and 7 have been ful ly characterised by both spectroscopic and crystallographic techniques .