The π-(Hydroxyalkenyl)germane Complexes Rh(acac){η2-(E)-Et3GeCHCHC(OH)R2}(PCy3) (R = Me, Ph) as Intermediates in the Hydrogermylation of Alkynols Catalyzed by Rh(acac)(cyclooctene)(PCy3)

The (hydroxyalkenyl)germanes ( E )-R 3 GeCH CHC(OH)R‘ 2 (R = Et, Ph; R‘ = Me, Ph) are prepared in quantitative yield, and in a catalytic manner, by addition of germanes to the alkynols HC⋮CC(OH)R‘ 2 (R‘ = Me, Ph) in the presence of the complex Rh(acac)(cyclooctene)(PCy 3 ). During the reactions four cycles are evident. They have as a common point the intermediates Rh(acac){η 2 -( E )-CH(GeR 3 ) CHC(OH)R‘ 2 }(PCy 3 ), which have been isolated for R = Et and R‘ = Me, Ph.