A re-examination of the reaction between 1,1 '-bis(diphenylphosphino)ferrocene (dppf) diselenide and [Ru-3(CO)(12)]. Electrochemical behaviour of the isomeric Nido-clusters [Ru-3(mu(3)-Se)(2)(dppf)(CO)(7)] and [Ru-3(mu(3)-Se)(2)(mu-dppf)(CO)(7)] and crystal structure of [Ru3Se{mu-P(Ph)C5H4FeC5H4PPh2}(mu-OCPh)(CO)(6)]

The reactions of 1,1'-bis(diphenylphosphino)ferrocene diselenide (dppfSe2) with [Ru-3(CO)(12)] at 60 and 110 degreesC afford, respectively, the two isomeric nido-clusters [Ru-3(mu (3)-Se)(2)(dppf)(CO)(7)] (2) and [Ru-3(mu (3)-Se)(2)(CO)(7)(mu -dppf)] (3) which contain dppf as chelating and bridging ligand, respectively. The chelated derivative 2, attainable under kinetic control, can be converted to the more stable bridged cluster 3 by thermal treatment in toluene solution. Moreover the cluster [R mu Se-3{mu -P(Ph)C5H4FeC5H4PPh2}(mu -OCPh)(CO)(6)] (4) was isolated as a minor product. Its cluster core consists of a metal triangle capped by a selenium atom and bridged on two sides, respectively, by a phosphido ligand and by a benzoyl group both deriving from multiple fragmentation of dppf diselenide and migratory insertion of a Ph ring into a CO ligand. Isomers 2 and 3 present different electrochemical behaviour, the bridged one giving a more complicated voltammetric pattern