Chemical transformations on phosphido-bridged clusters. Reactions of the .mu.3-.eta.3-allenyl complex Ru3(CO)8{.mu.3-.eta.3-CH2C:C(i-Pr)}(.mu.-PPH2). Reversible CO addition, adduct formation with P(OMe)3, hydrogenation, and alkyne insertion

In a preceding paper the authors reported the synthesis of the allenyl cluster Ru/sub 3/(CO)/sub 8//..mu../sub 3/-eta/sup 3/-CH/sub 2/CC(i-Pr)/(..mu..-PPh/sub 2/) (1) via methylene (CH/sub 2/) addition to the acetylide Ru/sub 3/(CO)/sub 6/(..mu..-CO)/sub 2//..mu../sub 3/-eta/sup 2/-C==C(i-Pr)/(..mu..-PPh/sub 2/) (2). Like its isoelectronic 48-electron acetylide counterpart, 2, cluster 1 behaves as if it is coordinativley unsaturated, adding nucleophiles with great facility at ambient temperatures. Lewis base additions to clusters without ligand dissociation have been observed recently for several other systems, but only in very few cases have the scope and synthetic implications of such reactivity been explored. Here they report a series of reactions of the cluster 1 including reversible CO addition, formation of a phosphite adduct, a novel hydrogenation of the unsaturated ligand, and a series of alkyne insertions leading to hydrocarbon chain extension.