The first chromate containing both Cr2O7 and Cr3O10 groups, bis(1,3-bis(4-piperidinium)propane) dichromate trichromate monohydrate: Synthesis and crystal structure

A new organic-inorganic hybrid material (C13H28N2)2[Cr2O7][Cr3O10]·H2O (1) was synthesized by slow solvent evaporation at room temperature, and its crystal structure was determined by single crystal X-ray diffraction. This compound crystallizes in the monoclinic space group P21/c. The asymmetric unit contains two crystallographically independent 1,3-bis(4-piperidinium)propane, (H2bppp)2+ cations (A and B), one trichromate Cr3O102− anion, one dichromate Cr2O72− anion, and one water molecule. All these entities are interconnected into a complicated two-dimensional hydrogen bonded network via N–H⋯O and O–H⋯O hydrogen bonds. Furthermore, this structure is stabilized by a large number of C–H⋯O interactions, thus establishing a three-dimensional network structure. This compound appears to be the first example of chromates containing both Cr2O7 and Cr3O10 groups.