Synthesis and structures of dinuclear iron, molybdenum and tungsten complexes derived from (PhCHCHPh)-coupled bis(cyclopentadiene)

Abstract Reductive coupling of phenylfulvene with amalgamated calcium metal followed by hydrolysis yields CpPhCHCHPhCp ( 1 ) in high yield. Refluxing ligand 1 and Fe(CO) 5 in xylene produces (PhCHCHPh)-coupled bis(cyclopentadienyl) tetracarbonyl diiron (PhCHCHPh)[(η 5 -C 5 H 4 )Fe(CO) 2 ] 2 ( 2 ) as a mixture of meso ( 2 - meso ) and racemic isomers ( 2 - rac ). The pure racemic isomers of the Mo and W analogues ( 3 - rac and 4 - rac ) have been synthesized by lithiation of ligand 1 and addition of (MeCN) 3 M(CO) 3 (M = Mo, W) followed by oxidation with 2 equiv. of ferrocenium tetrafluoroborate. All the new complexes have been fully characterized. The molecular structures of 1 - meso , 2 - meso , 2 - rac , 3 - rac , and 4 - rac have been determined by X-ray diffraction analysis.