Accessing multimetallic complexes with a phosphorus(i) zwitterion

Abstract

We present the synthesis of a zwitterionic triphosphenium molecule, ^tBu(C₅H₂)(PPh₂)₂P^I (L), which can act as a single- or multidentate ligand with group 6, 7, 8 and 9 metal carbonyl complexes. Group 6, [M(CO)₅L] complexes are formed under photolytic conditions, where the metal is bound at the P(I) center. In the case of Mo(CO)₆, the bimetallic complex [M(CO)₅LMo(CO)₃] 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 [M₂(CO)_nL], 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.