Metal–Organic Frameworks (MOFs) of a Cubic Metal Cluster with Multicentered Mn^IMn^I Bonds

Abstract

MOFs with both multicentered metal-metal bonds and low-oxidation-state (LOS) metal ions have been underexplored hitherto.H ere we report the first cubic [Mn I 8 ]c lusterbased MOF (1)w ith multicentered Mn I ÀMn I bonds and + 1 oxidation state of manganese (Mn I or Mn(I)), as is supported by single-crystal structure determination, XPS analyses,a nd quantum chemicalstudies.Compound 1 possesses the shortest Mn I À Mn I bond of 2.372 . Theoretical studies with density functional theory (DFT) reveal extensive electron delocalization over the [Mn I 8 ]cube.The 48 electrons in the [Mn I 8 ]cube fully occupyh alf of the 3d-based and the lowest 4s-based bonding orbitals,with six electrons lying at the nonbonding 3dorbitals.T his bonding feature renders so-called cubic aromaticity.M agnetic properties measurements show that 1 is an antiferromagnet. This work is expected to inspire further investigation of cubic metal-metal bonding,M OF materials with LOS metals,a nd metalloaromatic theory.Inthe past two decades,metal-organic frameworks (MOFs) have attracted much attention due to their fascinating topological structures and various functions in adsorption, separation, catalysis,c hemical sensing,a nd magnetic properties. [1, 2] In construction and design of MOFs with characteristic properties and functions,m etal ions play ac rucial role. Especially,t hrough small bridging molecules metal ions can be aggregated into more complicated cages/clusters,w hich serve as nodes and can form highly connected MOFs. [3] In more than 25 000 MOF-related publications,c luster-based MOFs with low-oxidation-state (LOS) metals and multicentered metal-metal bonding were unknown until recently when aZ n 8 cluster was synthesized. [4] On the other hand, oxidation state as acentral concept in chemistry is associated with both the electronic structure and chemical properties of agiven atom. Among all the elements in the periodic table,t he lowest oxidation state is À4f or carbon, [5a] and the highest oxidation state is + 9f or iridium. [5b] Due to their low electronegativity,m etals tend to have high oxidation states,w hereas LOS of metals are rare and often offer opportunity for unique electronic structures and properties.R ecently,t he number of LOS metal-metal bonded compounds have rapidly increased since Carmonas report of the singly bonded zinc(I) dimer [Cp*ZnZnCp*] (Cp* = C 5 Me 5 ). [6] An umber of M I À M I bonded compounds have been synthesized, including M = Cd, [7,12d] Cr, [8] In, [9] Mg, [10] Fe, [11, 12e] Mn, [12] Co, [13] and Ni. [14] These compounds all contained dinuclear metals (except In) and were obtained by using sterically demanding ligands.M ost of them are unstable in air.S of ar multicentered Mn I À Mn I bonded polyatomic clusters have not yet been reported, although dinuclear Mn I À Mn I bonded compounds are known. [12] In this work, we report the synthesis of the first polyatomic Mn I compound {[Mn I 8 Mn II 3 (H 2 O) 6 (HL) 12 ]-(OH) 2 ·17 H 2 O} n (1)( L = tetrazole dianion), which features + 1o xidation sta...

Decorating CeO2 Nanoparticles on Mn2O3 Nanosheets to Improve Catalytic Soot Combustion

“…The chemical state of the superficial Mn species on the catalysts is the mixture of Mn 3+ and Mn 4+ . The multiplet splitting of Mn 3s peaks in Mn 3s spectra is often utilized to determine chemical state of Mn species Figure S4 and Table S5 show the splitting width of the Mn 3s peaks, which is sensitive to the chemical state of the superficial Mn species with the smaller Δ E values for the higher chemical states. , We observed the coexistence of Mn 3+ and Mn 4+ on the surface of the catalysts, which is in accordance with the results of the Mn 2p spectra.…”

The Planar CoB18− Cluster as a Motif for Metallo‐Borophenes

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Hierarchical Construction and Magnetic Difference of {Co12M12} (M = Co2+/Cd2+) Aggregates from {Co14} Cluster-Based Precursors in the Presence of Homo/Heterometal Salts

“…For {Co 12 Cd 12 }, the χ M T values decreased gradually to a minimum of 9.00 cm 3 ·K·mol –1 at 2 K. The reciprocal molar susceptibilities between 25 and 300 K followed the Curie–Weiss law of 1/χ M = ( T – Θ)/ C with Curie constants of 79.81 and 44.72 cm 3 ·K·mol –1 and Weiss constants of −22.48 and −16.09 K for {Co 24 } and {Co 12 Cd 12 }, respectively (Figure S4). The negative Θ values suggested dominant antiferromagnetic interactions between the metal centers and/or the strong spin-orbit coupling effect of the Co 2+ centers . Field-cooled (FC) magnetization (2–20 K) under different applied magnetic fields was measured.…”