Influence of the nacnac Ligand in Iron(I)-Mediated P4 Transformations

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