Synthesis and characterization of novel σ-alkynyl cyclopentadienyl iron(II) complexes [Fe(CCR)L 2(η-C 5H 5)] [L  CO; L 2  bis(diphenylphosphino)methane (dppm)]. Crystal structure of [Fe(CCC 6H 5)(dppm)(η-C 5H 5)

Abstract

The synthesis of novel σ-alkynyl cyclopentadienyl iron(II) complexes of the type [Fe(CCR)L 2(η-C 5H 5)] [L  CO; R  SiMe 3, tBu, CO 2Me; L 2 = bis(diphenylphosphino)methane (dppm), R  SiMe 3, tBu, CCO 2Me, H, C 6H 5] is described. IR and 1, 31P{ 1H} and 13C NMR data are discussed. The structure of [Fe(CCPh)(dppm)(η-C 5H 5)] has been determined by an X-ray diffraction study. the coordination around the Fe atom of the cyclopentadienyl ring (considered as bonded at its centroid), the two P atoms of the dppm molecule acting as a chelating ligand, and the terminal carbon of the phenylacetylide ligand, can be described as a three-legged piano stool. The stabilities of the dppm chelate rings in the complexes have been studied, and their reactions with CO under atmospheric or higher pressure examined.