Pd(II)- and Pt(II)-Diimine Complexes Containing (1-Aza-15-crown-5)dithiocarbamate and (1-Aza-18-crown-6)dithiocarbamate: Structural Transformation and Luminescence Studies

A number of Pd(II)- and Pt(II)-diimine complexes were synthesized by reacting [Pd(bpy)Cl2], [M(phen)Cl2] (M = Pd, Pt), and [Pd(phenpz)Cl2] with dithiocarbamates (L1 and L2). Complexes 1, 3a, and 3b show respective intramolecular Pd(II)···Pd(II) contacts of 3.576, 3.529, and 3.430 Å, whereas complex 4 displays intra- and intermolecular Pd(II)···Pd(II) contacts of 3.640 and 3.667/4.404 Å, respectively. Complex 6 also exhibits respective intra- and intermolecular Pt(II)···Pt(II) contacts of 3.510 and 4.160 Å. Moreover, complexes 2 and 3b have Na+ encapsulated inside the azacrown cavities, and two ClO4– anions with trans- or cis-coordination to the Na+ ions. Besides, complexes 4 and 5b also have two encapsulated Na+ or K+ ions, respectively, leading to a syn- or anti-form structure through bridging ClO4– anions. Unlike complexes 2, 3b, 4, and 5b with encapsulated Na+ or K+ anions, complex 6 has two encapsulated Ag+ and bridging NO3– ions to form a syn-form structure. Remarkably, grinding complex 2 with CH3OH generally led to a similar framework of {[Pt2(bpy)2(NaL2)2(ClO4)2](ClO4)2}n as a 1D coordination polymer, and complex 3b can actually be rearranged into complex 3a while grinding with CH3OH. Furthermore, complexes 5b and 6 show the respective low-energy emissions at 593 and 555 nm at room temperature.