TEMPO coordination and reactivity in group 6; pseudo-pentagonal planar (eta(2)-TEMPO)(2)CrX (X = Cl, TEMPO)

The exposure of Crcl(2)(THF)(2) to 1 equiv. of TEMPO and 1 equiv. [TEMPO]Na afforded (eta(2)-O,N-TEMPO)(2)Crcl (1, 67%); addition of [TEMPO]Na to 1 yielded (eta(2)-O,N-TEMPO)(2)Cr(TEMPO) (2). Both 1 and 2 exhibit pseudo-pentagonal planar (PPP) geometry, instead of myriad alternatives. Calculations and spectral studies suggest the solid-state geometry persists in solution.