Access to Unsaturated Ruthenium Complexes via Phosphine Complexation with Triphenylborane: Synthesis and Structure of a Zwitterionic Arene Complex, (η<sup>6</sup>-Ph-BPh<sub>2</sub>H)Ru(PMe<sub>3</sub>)<sub>2</sub>(SiMe<sub>3</sub>)
作者:Vladimir K. Dioumaev、Karl Plössl、Patrick J. Carroll、Donald H. Berry
DOI:10.1021/om9908938
日期:2000.8.1
Triphenylborane, BPh3, serves as a phosphine "sponge", scavenging free PMe3 from alkane solutions of the 18e(-) complex (PMe3)(4)Ru(SiMe3)H to form sparingly soluble Ph3B-PMe3 and the 16e(-) (PMe3)(3)Ru(SiMe3)H. Under nitrogen atmosphere the 16e(-) (PMe3)Ru-3(SiMe3)H forms a dimeric N-2 adduct, [(PMe3)(3)Ru(SiMe3)H](2)N-2. Both the 16e(-) complex and its N-2 adduct exist in equilibrium with the 18e(-) silene complex, (PMe3)(3)Ru(CH2=SiMe2)H-2. However, long reaction times in the presence of excess borane leads to removal of another phosphine ligand as Ph3B-PMe3 and formation of a new zwitterionic complex, (eta(6)-PhBPh2H)Ru(PMe3)(2)(SiMe3) (5), in which a molecule of borane has abstracted a ruthenium hydride ligand and also coordinates as an eta(6)-arene. The merits and Limitations of BPh3 as a phosphine removal agent are discussed. Compound 5 has been characterized by single-crystal X-ray analysis and exhibits unusually long Ru-C-arene bonds.