Synthesis and Structural Characterization of Lithium and Iron Complexes Containing a Chelating Phenolate Phosphane Ligand

The preparation and characterization of lithium and iron(II) complexes containing a potentially tridentate biphenolate phosphane ligand are reported. Deprotonation of 2,2′‐phenylphosphanyl‐bis(4,6‐di‐ tert ‐butylphenol) (H 2 L Ph ) with one or two equivalents of n BuLi in diethyl ether solutions at –35 °C produces binuclear {Li(HL Ph )(OEt 2 )} 2 or tetranuclear Li 4 (L Ph ) 2 (OEt 2 ) 3 , respectively. An X‐ray study of {Li(HL Ph )(OEt 2 )} 2 showed it to be a C i ‐symmetric dimer composed of two Li(HL Ph )(OEt 2 ) units linked with dative O–Li bonds involving phenolate oxygen donor atoms whereas that of Li 4 (L Ph ) 2 (OEt 2 ) 3 revealed a C 2 ‐symmetric structure in which the two biphenolate phosphane ligands are linked with four lithium atoms that bind to three diethyl ether molecules. Treatment of FeCl 2 with one or two equivalents of Na 2 (L Ph )(DME) 2 in THF at –35 °C generates binuclear Fe 2 (L Ph ) 2 (THF) 2 or mononuclear Fe(HL Ph ) 2 (THF) 2 , respectively. The two iron(II) centers in Fe 2 (L Ph ) 2 (THF) 2 are antiferromagnetically coupled.