Influence of the nacnac Ligand in Iron(I)‐Mediated P(4) Transformations

A study of P(4) transformations at low‐valent iron is presented using β‐diketiminato (L) Fe(I) complexes [LFe(tol)] (tol=toluene; L=L(1) (1 a), L(2) (1 b), L(3) (1 c)) with different combinations of aromatic and backbone substituents at the ligand. The products [(LFe)(4)(μ(4)‐η(2):η(2):η(2):η(2)‐P(8))] (L=L(1) (2 a), L(2) (2 b)) containing a P(8) core were obtained by the reaction of 1 a,b with P(4) in toluene at room temperature. Using a slightly more sterically encumbered ligand in 1 c results in the formation of [(L(3)Fe)(2)(μ‐η(4):η(4)‐P(4))] (2 c), possessing a cyclo‐P(4) moiety. Compounds 2 a–c were comprehensively characterized and their electronic structures investigated by SQUID magnetization and (57)Fe Mössbauer spectroscopy as well as by DFT methods.