Chelate Complexes of Functionalized Cycloheptatrienyl Ligands: 17- and 18-Electron Molybdenum Complexes with Linked Cycloheptatrienyl−Phosphane Ligands and Their Use in Transition Metal Catalysis

✍ Scribed by Matthias Tamm; Kim Baum; Thomas Lügger; Roland Fröhlich; Klaus Bergander

• Publisher: John Wiley and Sons
• Year: 2002
• Tongue: English
• Weight: 482 KB
• Volume: 2002
• Category: Article
• ISSN: 1434-1948
• DOI: 10.1002/1099-0682(200203)2002:4<918::aid-ejic918>3.0.co;2-e

✦ Synopsis

The synthesis of P-functionalized molybdenum chelate complexes incorporating the linked cycloheptatrienylphosphane ligand [2-(diphenylphosphanyl)phenyl]cycloheptatrienyl, o-Ph 2 P-C 6 H 4 -C 7 H 6 , is described. The air-stable ligand precursor [2-(cyclohepta-2,4,6-trienyl)phenyl]diphenylphosphane (2) can be obtained in large quantities by addition of lithiated 2-BrC 6 H 4 PPh 2 (1) to the tropylium cation C 7 H 7 + . Hydride abstraction employing the trityl cation, Ph 3 C + , results in the formation of the tricyclic phosphonium salt 3. The P-functionalized cycloheptatriene 2 acts as an eight-electron ligand on reaction with Mo(CO) 6 to afford the cycloheptatriene-phosphane complex [(o-Ph 2 PC 6 H 4 -η 6 -C 7 H 7 )Mo(CO) 2 (P-Mo)] (4) as a single, chiral regioisomer, which undergoes clean hydride abstraction on treatment