Crystal structure and dynamic behavior of a new class of monocationic organometallic Pd-II compounds with two molecules of bidentate ligands: [Pd(L-L)(N-N)(CH2NO2)][PF6] (L-L = N-N, dppp)

Two new classes of organometallic palladium(II) compounds, namely [Pd(N-N)( CH2NO2)(2)] and [Pd(L-L) (N-N)(CH2NO2)][PF6] [N-N = 2,2'-bipyridine, 1,10-p henanthroline and their substituted derivatives; L-L = 1,3-bis(diphenylphos phino)propane or N-N] have been synthesized and fully characterized both in the solid state and in solution. The crystal structures of [Pd(phen)(2)(CH 2NO2)][PF6] and of [Pd(dppp)(tmphen)(CH2NO2)][PF6] show a square-planar coo rdination geometry for the palladium atom and an unexpected monodentate coo rdination for the N-N ligand. The behavior in solution, investigated by NMR spectroscopy, shows the presence of dynamic processes involving only the N -N molecules. This fluxional behavior is different for [Pd(NN)(2)(CH2NO2)][ PF6] and [Pd(dppp)(N-N)(CH2NO2)][PF6]: in the former it most likely involve s the substitution of the nitrogen atom trans to the CH2NO2 moiety by the u ncoordinated nitrogen atom of the other N-N ligand; in the latter it may in volve the exchange of the two nitrogen atoms at the same coordination site (flipping).