Substitution of [Ru3(µ-H)3(µ3-Bi)(CO)9] with monodentate Group 15 donor ligands

Abstract

An investigation into the substitution chemistry of the bismuth-capped triruthenium cluster[Ru₃(µ-H)₃(µ₃-Bi)(CO)₉](1) with Group 15 donor ligands has been carried out. It has been found that for the ligands PPh₃, As(C₆H₄Me-p)₃, SbPh₃, and P(OMe)₃ up to three carbonyl ligands can be substituted but for the more basic ligand PEt₃ only the mono- and di-substituted clusters can be formed. Structures for the compounds formed have been proposed on the basis of spectroscopic evidence, and it is suggested that for each ligand investigated the major isomers of the mono- and di-substituted clusters have the substituting ligands occupying axial sites. Of the monosubstituted clusters, only the P(OMe)₃ complex shows signals which may be attributed to a minor isomer in solution, while, of the disubstituted clusters, both the P(OMe)₃ and PEt₃ clusters are assigned as having three isomers each in solution. For the trisubstituted clusters the preferred structure is one having two axial and one equatorial carbonyl ligand substituted. This differs from the structure suggested for the formally isoelectronic clusters [M₃(µ-H)₃(µ₃-CX)(CO)₆L₃](M = Ru or Os) which have all three substituting ligands in axial sites. A possible explanation for this difference is included.