Synthesis and structure determination of stereoisomeric 2,2’-dibenzoyl-3,3’,4,4’-tetramethyl-1,1’-diphosphaferrocenes

Abstract

Reaction of 3,3’,4,4’-tetramethyl-1,1’-diphosphaferrocene 1 with an excess of benzoyl chloride and AlCl3 afforded a ~1:1 mixture of meso- and rac-2,2’-dibenzoyl-3,3’,4,4’-tetramethyl-1,1’- diphosphaferrocenes 2, which were separated by column chromatography. The less polar diastereomer was transformed into its bis-W(CO)5- complex 3. The single crystal X-ray study revealed that this complex contains the meso-2 ligand. Therefore, the more polar diastereomer must be rac-2. It has been suggested that the splitting pattern of the phospholyl protons signal in the 1 H NMR spectra can be used for stereochemistry assignments.