Synthesis, crystal structure and two-dimensional infrared correlation spectroscopy of a layer-like transition metal (TM)-oxalate templated polyoxovanadium borate

A novel polyoxometalate (POM) Na2(H2en)2{(VO)10[B14O30(OH)2]2}{Mn4(C2O4) [B2O4(OH)2]2}Mn(H2O)2·(H3O)12(H2O)191 (en=ethylenediamine), which is a layer-like transition metal (TM) oxalate templated polyoxovanadium borate, has been synthesized under hydrothermal conditions and characterized by EPR, elemental analysis, thermal analysis, single crystal X-ray diffraction and 2D IR correlation spectroscopy studies, respectively. This compound crystallized in the triclinic space group P1¯ with a=14.3842(4)Å, b=14.6837(3)Å, c=15.8681(4)Å, α=64.48(1)°α=64.48(1)°, β=64.68(1)°β=64.68(1)°, γ=63.93(1)°γ=63.93(1)°, V=2596.80(11)Å3 and Z=2Z=2. The cluster anion with an open central cavity has a central band of ten edge-sharing VO5 square pyramids, which is capped top and bottom by two crown-like polyborate ligands of formula [B14O30(OH)2]20−. There is a fragment of {Mn4(C2O4)[B2O4(OH)2]2}2− fixed in the central cavity as a guest part. The cluster units are connected to form a two-dimensional (2D) framework by octahedral Mn(II) and Na+ sites. In addition, we first introduce the generalized 2D correlation spectroscopy to explore the POMs and obtain the dynamic information about structural changes of POMs.

Graphical abstractA novel polyoxovanadium borate has been synthesized by hydrothermal method. It is the first TM oxalate templated polyoxovanadium borate with a 2D layer structure constructed from unprecedented V10B28O74 cluster units and coordination complex fragments. The 2D IR correlation spectroscopy was first introduced to explore the polyoxometales (POMs) and clearly probed the subtle structural changes of the title compound induced by temperature and magnetic intensity variations.Figure optionsDownload full-size imageDownload as PowerPoint slide