Novel layered heterobimetallic fluorides with large optical band gaps

초록

Two heterobimetallic fluoride compounds, [Cd(C4H6N2)(4)](3)[ZrF7](2) and [Zn(C4H6N2)(4)](3)[HfF7](2) (C4H6N2 = 3methylpyrazole), consisting of the alternating asymmetric d(0) transition metal-centered pentagonal bipyramids and polarizable d(10) transition metal-centered octahedra were synthesized by hydrothermal reactions. Single crystal X-ray diffraction analysis suggests that both compounds crystallizing in the trigonal space group, P (3) over bar (No. 147), exhibit layered structures containing hexagonal windows with 12 membered rings. The observed hexagonal windows in the structures are attributed to the cis -directing property of anionic moieties for d(0) metal cations, and strong intra-and inter-layer hydrogen bonding networks between the organic linkers and fluorides. Both compounds reveal large optical band gaps of ca. 5.2 eV attributable to the distortions in the octahedral environment of d(10) metal cations, and the larger content of electron-rich fluorides in the asymmetric polyhedra of d(0) metal cations. An interesting transformation reaction of [Cd(C4H6N2)(4)](3)[ZrF7](2) to [Cd(H2O)(3)](2)[ZrF8] under a hydro thermal condition in presence of aqueous HF is also presented.

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