Synthesis and Structural Characterization of a Metal Cluster and a Coordination Polymer Based on the [Mn6(μ4-O)2]10+ Unit

A new 1-D coordination polymer {[Mn6O2(O2CMe)10(H2O)4]·2.5H2O}∞ (1·2.5H2O)∞ and the cluster [Mn6O2(O2(O2CPh)10 (py)2(MeCN)(H2O)]·2MeCN (2·2MeCN) are reported. Both compounds were synthesized by room temperature reactions of [Mn3(μ3-O)(O2CR)6(L)2(L′)] (R = Me, L = L′ = py, (1·2.5H2O)∞; R = Ph, L = py, L′ = H2O, 2·2MeCN) in the presence of 3-hydroxymethylpyridine (3hmpH) in acetonitrile. The structures of these complexes are based on hexanuclear mixed-valent manganese carboxylate clusters containing the [Mn4IIMn2III(μ4-O)2]10+ structural core. (1·2.5H2O)∞ consists of zigzag chain polymers constructed from [Mn6O2(O2CMe)10(H2O)4] repeating units linked through acetate ligands, whereas 2·2MeCN comprises a discrete Mn6-benzoate cluster

Synthesis and Characterization of a Linear [Mn3(O2CMe)4(py)8]2+ Complex

Two new compounds that consist of the linear trinuclear manganese(II) cation [Mn3(O2CMe)4(py)8]2+ cocrystallizing with different counteranions (I3−, [1]; ClO4−, [2]) are reported. Complex 1 was prepared from the reaction of [Mn(O2CMe)2] · 4H2O with I2 in MeCO2H/py, whereas complex 2 was isolated from the reaction of [Mn3O(O2CMe)6(py)3] · py with [Mn(ClO4)2] · 6H2O in MeCN/py. The crystal structures of both compounds were determined by single crystal X-ray crystallography. Magnetic susceptibility studies that were performed in microcrystalline powder of 1 in the 2–300 K range revealed the presence of antiferromagnetic exchange interactions that resulted in an S = 5/2 ground spin state

Giant Heterometallic [Mn36Ni4]0/2− and [Mn32Co8] “Loops-of-Loops-and-Supertetrahedra” Molecular Aggregates

We report the synthesis, crystal structures and magnetic properties of the giant heterometallic [Mn36Ni4]2−/0 (compounds 1, 2)/[Mn32Co8] (compound 3) “loops-of-loops-and-supertetrahedra” molecular aggregates and of a [Mn2Ni6]2+ compound (cation of 4) that is structurally related with the cation co-crystallizing with the anion of 1. In particular, after the initial preparation and characterization of compound [Mn2Ni6(μ4-O)2(μ3-OH)3(μ3-Cl)3(O2CCH3)6(py)8]2+[Mn36Ni4(μ4-O)8(μ3-O)4(μ3-Cl)8Cl4(O2CCH3)26(pd)24(py)4]2− (1) we targeted the isolation of (i) both the cationic and the anionic aggregates of 1 in a discrete form and (ii) the Mn/Co analog of [Mn36Ni4]2− aggregate. Our synthetic efforts toward these directions afforded the discrete [Mn36Ni4] “loops-of-loops-and-supertetrahedra” aggregate [Mn36Ni4(μ4-O)8(μ3-O)4(μ3-Cl)8Cl2(O2CCH3)26(pd)24(py)4(H2O)2] (2), the heterometallic Mn/Co analog [Mn32Co8(μ4-O)8(μ3-O)4(μ3-Cl)8Cl2(μ2-OCH2CH3)2(O2CCH3)28(pd)22(py)6] (3) and the discrete [Mn2Ni6]2+ cation [Mn2Ni6(μ4-O)2(μ3-OH)4(μ3-Cl)2(O2CCH3)6(py)8](ClO4)(OH) (4). The structure of 1 consists of a mixed valence [Mn28IIIMn8IINi4II]2− molecular aggregate that contains two Mn8IIINi2II loops separated by two Mn6IIIMn4II supertetrahedral units and a [Mn2IIINi6II]2+ cation based on two [MnIIINi3II(μ4-O)(μ3-OH)1.5(μ3-Cl)1.5]4+ cubane sub-units connected through both mono- and tri-atomic bridges provided by the μ4-O2− and carboxylate anions. The structures of 2–4 are related to those of the compounds co-crystallized in 1 exhibiting however some differences that shall be discussed in detail in the manuscript. Magnetism studies revealed the presence of dominant ferromagnetic interactions in 1–3 that lead to large ground state spin (ST) values for the “loops-of-loops-and-supertetrahedra” aggregates and antiferromagnetic exchange interactions in 4 that lead to a low (and possibly zero) ST value. In particular, dc and ac magnetic susceptibility studies revealed that the discrete [Mn36Ni4] aggregate exhibits a large ST value ~ 26 but is not a new SMM. The ac magnetic susceptibility studies of the [Mn32Co8] analog revealed an extremely weak beginning of an out-of-phase tail indicating the presence of a very small relaxation barrier assignable to the anisotropic Co2+ions and a resulting out-of-phase ac signal whose peak is at very low T

New Zn2+ Metal Organic Frameworks with Unique Network Topologies from the Combination of Trimesic Acid and Amino-Alcohols

A series of new Zn2+-trimesate (btc(3-)) metal organic frameworks (MOFs) has been isolated in the presence of various amino-alcohols under solvothermal conditions. Thus, the reaction of ZnCl2 with trimesic acid (H(3)btc) and the amino alcohols triethanolamine (teoa), 2(hydroxymethyl)piperidine (hmpip), N-tert-butyldiethanolamine (tbdeoa), 1,4-bis(2-hydroxyethyl)piperazine (bhep), N-methyldiethanolamine (mdeoa), or 4-(2-hydroxyethyl)morpholine (hem) in a 1.6:1:5.6 molar ratio in DMF afforded compounds (teoaH)(2)[Zn(btc)(1.33)] (MOAAF-1) (MOAAF = metal organic amino-alcohol framework), (NH2Me2)(2)(hmpipH)[Zn-3(btc)(3)] (MOAAF-2), (NH2Me2)-(tbdmaH)(2)[Zn-3(btc)(3)] (MOAAF-3) (tbdma = N-tert-butyl-dimethylamine), (NH2Me2)(bhepH(2))[Zn-3(btc)(3)] (MOAAF-4), (NH2Me2) [Zn-4(btc)(3)(mdeoa)(2)] (MOAAF-5), and (NH2Me2)[Zn-4(btc)(3)(hem)(2)] (MOAAF-6), respectively. The compounds display 3D structures with relatively large cavities (4-10 angstrom) and high potential solvent-accessible areas (38-68% of the unit cell volumes). A number of novel structural features are revealed in the reported MOFs, such as unprecedented dinuclear [Zn-2(COO)(5)](-1) secondary building units (SBUs) and unique network topologies (e.g., in compounds MOAAF-2, MOAAF-3, MOAAF-5, and MOAAF-6). The amino-alcohols employed played a key role for the appearance of such novel structural features in MOAAF 1-6 since they were found to act as bases responsible for the deprotonation of H(3)btc, templates, and chelating ligands. Specifically, most of the compounds synthesized were shown to be templated by protonated amino alcohols that are involved in hydrogen bonding interactions with the frameworks, whereas in two cases (compounds MOAAF-5 and MOAAF-6) the amino alcohols acted as chelating ligands affecting significantly the underline topology of the MOFs. The thermal stability and photoluminescence properties of the MOFs are also discussed. This work represents the initial systematic investigation on the use of combination of amino alcohols and polycarboxylate ligands for the synthesis of new MOFs, demonstrating it as a powerful synthetic strategy for the isolation of novel MOFs

New metal–organic frameworks derived from pyridine-3,5-dicarboxylic acid: structural diversity arising from the addition of templates into the reaction systems

A series of new compounds prepared from reactions of pyridine-3,5-dicarboxylic acid (PDCH2), bipositive d-metal ions (Cd2+, Zn2+, Co2+ and Cu2+) and various template molecules [1,3-propanediol (pdH(2)), diethanolamine (deaH(3)), N-phenyldiethanolamine (phdeaH(2)), triethanolamine (teoaH(3)), 2-hydroxymethylpyridine (2hmpH), 3-hydroxymethylpyridine (3hmpH), 3-hydroxypropylpyridine (3hppH), and 4-hydroxymethylpyridine (4hmpH)] are reported. Among them, [[(CH3)(2)NH2](2)[Cd-2(PDC)(3)]](n).4nDMF.6nH(2)O, [1], [Mn(PDC)(DMF)](n), [2], [Mn-3(PDC)(2)(INA)(2)(DMF)(1.5)(H2O)(0.5)](n).nDMF.2nH(2)O, [3], and [Zn(PDC)(NMP)](n).nH(2)O, [4], are 3D coordination polymers, [Zn(PDC)(H2O)(DMF)](n), [5], [Zn(PDC)(3hmpH)](n.)nDMF.0.5nH(2)O, [6], and [Co(PDC)(3hmpH)(2)](n).0.25nDMF, [8], have 2D polymeric structures, while [Zn(PDC)(2hmpH)(2)](2).2DMF, [7], is a 0D binuclear complex, and [Cu(PDC)(3hmpH)(2)](n).0.5nDMF1.5nH(2)O, [9], is a chain polymer. Topological analysis reveals that some of the compounds display unusual structural architectures and two of them, in particular [1] and [3], present new topological types. The effect of the use of amino alcohol/polyol templates on the formation of the new compounds is also discussed in detail. The thermal stability of the prepared complexes was also studied. This study represents the initial systematic investigation on the use of a combination of polytopic nitrogen and oxygen-donor ligands and amino- or pyridine-alcohol templates for the synthesis of new MOFs

Inducing Single-Molecule Magnetism in a Family of Loop-of-Loops Aggregates: Heterometallic Mn40Na4 Clusters and the Homometallic Mn-44 Analogue

International audienceThe syntheses, crystal structures, and magnetic properties of a new family of heterometallic Mn40Na4 and homometallic Mn-44 loop-of-loops aggregates are reported. The reactions of [Mn3O(O2CMe)(6)(py)(3)]center dot py with 1,3-propanediol (pdH(2)) and 2-methyl-1,3-propanediol (mpdH(2)) in the presence of NaN3 afforded [Mn10Na(mu(3)-O)(2)(O2CMe)(13)(pd)(6)(py)(2)](4) (1)(4) and [Mn10Na(mu(3)-O)(2)(O2CMe)(13)(mpd)(6)(py)(H2O)](4) (2)(4), respectively. Mn40Na4 complexes (1)(4) and (2)(4) consist of four Mn-10 loops linked through Na+ ions to give a supramolecular aggregate with a saddle-like topology. Magnetic characterization of compound (1)(4) showed that each Mn-10 loop has an S = 4 ground-state spin and displays frequency-dependent in-phase and out-of-phase ac susceptibility signals. It also exhibits hysteresis loops that, however, are not typical of single-molecule magnets (SMMs) due to the existence of interloop interactions between the neighboring Mn-10 units of (1)(4) through the diamagnetic Na+ ions, and also intermolecular interactions between different Mn40Na4 aggregates. The magnetically discrete Mn-44 analogue was targeted with high priority and finally prepared from the reaction of [Mn3O(O2CMe)(6)(py)(3)]center dot py with pdH(2) in the presence of Mn(ClO4)(2)center dot 6H(2)O. The loop-of-loops structure of [Mn-44(mu(3)-O)(8)(O2CMe)(52)(pd)(24)(py)(8)](ClO4)(OH)(3) (3) is essentially identical to those of (1)(4) and (2)(4), with the most significant difference being that the four Na+ ions of (1)(4) and (2)(4) have been replaced with Mn2+ ions. Compound 3 is thus best described magnetically as a Mn-44 cluster. In accord with this description and the stronger exchange coupling between the four Mn-10 loops expected through the connecting Mn2+ ions, magnetic susceptibility measurements revealed that 3 has an S = 6 ground-state spin and displays frequency-dependent in-phase and out-of-phase ac signals. Magnetization vs dc field sweeps on single-crystals of 3 displayed scan rate- and temperature-dependent hysteresis loops confirming that complex 3 is a new SMM, and is thus the second largest Mn cluster and SMM reported to date