| Abstract
| - Both Binap and MeO-Biphep complexes ofRu(II) can coordinate a biaryl double bond immediately adjacent toone of the two P donors, thus making these ligands six-electron donors.In solution, there is exchange between the two halves of theC2 ligand, indicating dissociation of the biaryldouble bond.
- Ru(II) complexes of the chiral ligands Binap and MeO-Biphepcontaining six-electronhydrocarbon donors, such as Cp, a deprotonated pyrrole, or the benzenering of indole, attainthe 18-electron configuration by complexing a proximate biaryl doublebond. The solid-state structures for two of these,[RuCp(2)]BF4 and[Ru(indole)(2)](BF4)2(2 = (6,6‘-dimethoxybiphenyl-2,2‘-diyl)bis(bis(3,5-di-tert-butylphenyl)phosphine)),have been determinedby X-ray diffraction. They reveal that a biaryl double bond,immediately adjacent to oneP-donor, coordinates to the ruthenium, thus making the chelating liganda six-electron donor.The double bonds remain coordinated in solution as shown by HMBC13C,1H long-rangecorrelation spectroscopy. However, 2-D NMR exchange spectroscopysuggests that the biaryldouble bond is weakly coordinated since the two halves of theC2-symmetric Binap (or MeO-Biphep) ligands are in slow exchange at ambient temperature.
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