Synthesis and Structure of Chromium(VI) Nitrido Cyclopentadienyl Complexes

Abstract

A series of rare nitrido cyclopentadienyl complexes have been prepared of chromium(VI). An improved synthesis of NCr(I)(NPr i 2 ) 2 is provided, which reacts with NaCp to give NCr(η 1 -Cp)(NPr i 2 ) 2 ( 1 ) in 82% isolated yield. The η 1 -indenyl complex 2 can be prepared using a similar procedure. Replacement of one diisopropylamido ligand was accomplished to prepare NCr(NPr i 2 )Cp(O 2 CPh) ( 3 ), NCr(NPr i 2 )Cp(Cl) ( 4 ), and [NCr(NPr i 2 )Cp(NCMe)] + [SbF 6 ] − ( 5 ). In the series, the Cr–C interactions increase in bond order, 3 < 4 < 5, as the cyclopentadienyl compensates for the decreasing donor ability of the other ligands on chromium. The Ligand Donor Parameters (LDPs) for the η 1 -cyclopentadienyl and η 1 -indenyl ligands were measured as 13.73 and 13.76 kcal/mol, respectively. Compounds 1 – 5 were characterized by single-crystal X-ray diffraction.