Tris(thiocyanato-κN)tris(triphenylphosphine oxide-κO)europium(III)–(nitrato-κ2O,O′)bis(thiocyanato-κN)tris(triphenylphosphine oxide-κO)europium(III) (1/1)

The title co-crystal, [Eu(NCS)3(C18H15OP)3][Eu(NCS)2(NO3)(C18H15OP)3], contains two distinct neutral complexes. Each complex has threefold symmetry about its central Eu3+ ion. As a result, the nitrate-containing molecule contains disorder of its bidentate nitrate and two N-bound thiocyanate anions, while the [Eu(NCS)3(OPPh3)3] complex is fully ordered. There is a weak π–π stacking interaction between the phenyl rings of the two molecules [centroid–centroid distance = 4.138 (4) Å].