Accessing multimetallic complexes with a phosphorus(i) zwitterion.

We present the synthesis of a zwitterionic triphosphenium molecule, Bu(CH)(PPh)P (L), which can act as a single- or multidentate ligand with group 6, 7, 8 and 9 metal carbonyl complexes. Group 6, [M(CO)L] complexes are formed under photolytic conditions, where the metal is bound at the P(i) center. In the case of Mo(CO), the bimetallic complex [M(CO)LMo(CO)] is generated, which features bonds to both the phosphorus(i) center and the cyclopentadienyl moiety of the molecule. Interestingly, group 7 and 9 metal carbonyl dimers generate bimetallic complexes in the form [M(CO)L], where both metal centers are bound at the phosphorus(i) center. A detailed analysis of these molecules is provided, including X-ray diffraction, multinuclear NMR, infrared spectroscopy and computational investigations.