ABSTRACT
Alternatively, the reaction o f C o3(CO )9(|i,3-CBr) w ith [R u(r|-C 5H 5)(C O )2]~ and [H g R u (r|-C 5H 5)(C O )2 ]+ affords the m ixed-m etal cluster Co4Ru2H gC (CO )i3(T|-C5H 5)2 (see Scheme 8.3). T h is reaction is clearly quite complicated and involves, to some extent, fragmentation o f the precursor cluster compound, w hich then reassembles w ith the other two reagents. In order to prevent the core o f the tricobalt cluster from fragmenting during reaction, one carbonyl ligand on each cobalt can be substituted beforehand by a chelating face-capping trisphosphine ligand such as m’r-(diphenylphosphino) methane (tdpm) as shown in the Scheme. The tricobalt core in the resulting product, C o3(C O )6(tdpm )(|l3-C B r), is considerably more stable and in the reaction w ith the ruthenate species [R u (r|- C 5H 5)(C O )2]" remains intact to afford C o3(C O )6(tdpm ){^3-C -R u(r|-C 5H 5) (C O )2}. T h is cluster represents an example o f a tetrahedral sp3 carbon atom surrounded solely by metal atoms.
