“…[59, 60a] In the second approach (ix), ab is(carbodiimide), which is either generated from the bis(thiourea) or from bis(iminophosphorane), is reacted with an excess of amine yieldingt he related macrocyclic bis(guanidine)si nv ery good yields. [75] Compared with bis(amidine)s, bis(guanidine)s found multifarious applicationsa sc atalysts, [59,76] ions ensors, [60] pharmaceuticals, [63] or superbases. [61] To some extent, bis(guanidine) complexes (Figure 15) resemble the coordination patterns observed for bis(amidinate)s. Mononuclear complexes of type A are known for Eu, [77] Nd, [78] Sm, [79] Ta, [80] Ti, [68b] Y, [78,81] Yb, [78,81,82] Zr, [68b] and have been either directly derived from the bis(guanidine) [68b] or from in situ generated dinuclearalkali-metal complexes, [77][78][79][80][81] which are readily accessible from the reactiono f metallated secondary diamines with two equivalents of ac ar- Review bodiimide.…”