New hybrid Cd(ii) compounds: synthesis and structural characterization

Abstract

In an acidic solution, the room-temperature reactions of CdX2 (X(-) = Cl(-), Br(-) or CH3COO(-)) and organic N-heterocyclic molecules with or without SCN(-)/SeCN(-)/dca(-) (dca(-) = dicyanamide) created the five new hybrid Cd(ii) compounds [H2(4,4'-dtdpy)]2[CdBr4]SO4·2.5H2O (dtdpy = dithiodipyridine) 1, [H(2,2'-dtdpy)]2[CdBr4] 2, [(Hbim)2CdCl2(SCN)2] (bim = 2,2'-biimidazole) 3, [H2(pip)][Cd(SCN)4] (pip = piperazine) 4 and [CdL2] (L = HNC(OH)N(-)CN) 5. X-ray single-crystal diffraction analysis revealed that: (i) compound 1 is a double salt of [H2(4,4'-dtdpy)]SO4 and [H2(4,4'-dtdpy)][CdBr4], [H2(4,4'-dtdpy)]SO4 shows a two-dimensional (2D) supramolecular layer structure and [H2(4,4'-dtdpy)][CdBr4] is distributed in the space between the supramolecular layers; (ii) compounds 2 and 3 are mononuclear molecular entities. Of those, 2,2'-dtdpy and bim were only in situ monoprotonated; (iii) compound 4 contains a 2D supramolecular layered structure which is based on [Cd(SCN)4](2-) chains H2(pip)(2+)via NSCNNpip interactions; (iv) the three-dimensional (3D) compound 5 exhibits a rutile-related (4·6(2))2(4(2)·6(10)·8(3))-topology. The ligand L originates from the in situ nucleophilic addition of H2O with one -CN group of dca(-). Upon excitation, the solid-state compounds 3 and 4 emit blue light, and the solid-state compound 5 emits violet light.