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)A, b=14.6837(3)A, c=15.8681(4)A, 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)A3 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.