Three new hybrid compounds constructed from {PSb2Mo12O40} polyoxoanions, TMMC or organic amines

New Highly Charged Iron(III) Metal-Organic Cube Stabilized by a Bulky Amine

In this work, we report a new octanuclear cluster based on Fe^III and the ligand 1H-imidazole-4,5-dicarboxylic acid, [Et₃NH]₁₂[Fe₈(IDC)₁₂]·10DMF·13H₂O (1), with a metal core containing eight Fe^III connected by only one type of organic ligand. A peak at 573 m/z in the mass spectra of the compound suggests the adduct species {[Fe₈(IDC)₁₂]+8H}^4-. By X-ray photoelectron spectroscopy, the oxidation state of the iron cation was confirmed to be 3+, also identifying the presence of a quaternary nitrogen species, which act as a countercation of the anionic metal core [Fe₈(IDC)₁₂]^12-. Mössbauer spectra recorded at different temperatures show an isomer shift and quadrupole splitting parameters that confirm the existence of only Fe^III-HS in the structure of 1. X-ray analysis reveals that compound 1 crystallizes in the orthorhombic system space group Ibam, confirming a molecular cluster structure with an almost regular cube as geometry, with the Fe^III atoms located at the corners of the cube and connected by μ-1κ² N,O:2κ² N',O‴-IDC^3- bridges. Additionally, the magnetic measurements reveal a weak antiferromagnetic coupling in the Fe₈ ^III coordination cluster (J = -3.8 cm^-1). To the best of our knowledge, 1 is the first member of the family of cubes assembled with 1H-imidazole-4,5-dicarboxylic acid and Fe^III cation, exhibiting high pH stability over a broad pH range, making it an ideal candidate for the design of supramolecular structures and metal-organic frameworks.

Two Ni/Co-substituted sandwich-type germanomolybdates based on an unprecedented trivacant polyanion [α-GeMo10O36]8

Two Ni/Co-substituted sandwich-type germanomolybdates, {[M₃(NH₂-trz)₆(H₂O)₆][M₄(H₂O)₂(HGeMo₁₀O₃₆)₂]}·nH₂O (M = Ni²⁺ (1) and Co²⁺ (2), n = 10 (1) or 11 (2), NH₂-trz = 4-amino-1,2,4-triazole), have been obtained under hydrothermal conditions. 1 and 2 represent the first trivacant Keggin germanomolybdates involving unprecedented [α-GeMo₁₀O₃₆]^8- fragments and {M₃O₄} quasi-cubane building units. Both of them exhibit electrocatalytic behaviours for H₂O₂ reduction and photocatalytic properties for CO₂ conversion.