Palladium(II)-based cis,trans-1,3,5-triaminocyclohexane complexes demonstrating a variety of coordination modes and architectures

The reaction of cis,trans-1,3,5-triaminocyclohexane·3HX (L·3HX) with PdX2(X = Br, Cl) affords a wide range of coordination complexes that represent the different coordination modes available to L. Monoligand complexes [Pd(LH)Cl2]Cl (1) and [Pd(LH)Br2]2[PdBr4](2) demonstrate the bidentate coordination of L with the two cis amino ʹheadʹ groups chelating the palladium(II) ion and the third trans amino ʹtailʹ group being protonated. Diligand complexes [Pd(LH)2]X (X =(NO3)43, (SO4)24) show a ʹhead-to-headʹ coordination mode with the protonated trans amino groups adopting a conformation that positions them opposite to each other. Both sets of amino groups are engaged in coordination in a cyclic ʹhead-to-tailʹ fashion found in the hexanuclear ring clusters [{Pd(L)X}6]X6(X = Cl 5, Br 6). 5 and 6 are isostructural, both in the solid state and in solution, despite accommodating six chloro or bromo ligands into the cluster framework. A trinuclear complex [Pd{Pd(L)Cl2}2Cl2] (7) reveals ʹtail-to-tailʹ coordination of two ligands for the centre palladium(II) ion in addition to their ʹheadʹ amino groups individually chelating other palladium(II) ions. Complexes 1–7 were characterised by single-crystal X-ray diffraction, elemental analysis, IR and by NMR spectroscopy (1–6).