Expanding C-P Bond Chemistry

The first lanthanide-metal complex featuring a phosphinidene functional group has been reported by a team led by Jaqueline L. Kiplinger of Los Alamos National Laboratory (J. Am. Chem. Soc., DOI: 10.1021/ja7105306). This new compound class for the 4f elements could become "a platform for catalytic organophosphorus group-transfer processes and other C–P bond-forming reactions," Kiplinger says. The researchers made the complex by reacting a tridentate P–N–P pincer-type ligand with a lutetium precursor complex to form an isolatable intermediate, followed by treating the intermediate with mesitylphosphine (R′PH₂). Unlike transition metals, which can form terminal phosphinidenes (M=P), the lutetium version only forms a dimer with bridging phosphinidene groups (shown). In preliminary reactivity studies, the dimer breaks up and reacts like a terminal phosphinidene, transferring the organophosphorus group to aldehydes and ketones to make phosphaalkenes, such as R′P=C(C₆H₅)₂. "This phospha-Wittig chemistry suggests that we ultimately may be able to prepare a stable terminal lanthanide phosphinidene," Kiplinger adds.