Structures and sorption properties of the coordination polymers built up of 3d metal carboxylate polynuclear complexes

Abstract

The reaction of trinuclear acetate complexes Fe 2 MO(AcO) 6 (H 2 O) 3 (M = Ni 2+ , Co 2+ ) with 4,4´ bipyridine (bpy) results, depending on the reaction conditions, in porous coordination polymers with the composition Fe 2 MO(AcO) 6 (bpy) 1.5 (with retention of the metal core Fe 2 MO(AcO) 6 ) or nonporous coordination polymers with the composition M 2 (AcO) 4 (bpy) 2 (with destruction of the metal core Fe 2 MO(AcO) 6 ). The adsorption and desorption properties of the compounds Fe 2 MO(AcO) 6 (bpy) 1.5 with respect to nitrogen and hydrogen were studied. The reaction of hexanuclear benzoate complex Mn 6 O 2 (PhCOO) 10 (MeCN) 4 with bpy or trans 1,2 bis(4 pyridyl)ethylene (bpe) in DMF results in destruction of the metal core Mn 6 O 2 (PhCOO) 10 and formation of nonporous coordination polymers, while the pivalate com plex Mn 6 O 2 (Piv) 10 (EtOH) 3 (HPiv) under the same conditions gives rise to the coordination polymer containing Mn 6 O 2 (Piv) 10 structural blocks.The interest in porous coordination polymers (PCP) built up of 3d metals is caused by several reasons, in par ticular, by the possibility of creation of polyfunctional materials on the base of such compounds that can find application as magnetic materials with controlled proper ties as well as active components of sensors. 1-3 The po rous coordination polymers can possess the combination of properties that is unattainable in the case of other class es of compounds, for example, the ability to adsorb cer tain substrates (including gases) along with nontrivial mag netic properties caused by the exchange interaction of un paired electrons. However, the problem of effective di rected synthesis of the compounds comprising predeter mined polynuclear structural units has not been solved to date. Therefore, the preparation of PCP by cross linking of polynuclear blocks by appropriate bridging ligands is of special interest. In the overwhelming majority of exam ples of PCP having polynuclear blocks published to date, crystal lattices are formed by self assembly in the reaction mixtures (for example, the polymers having trinuclear blocks Fe 3 O 7+ ). 4 The examples of the preparation of PCP using polynuclear complexes as the building blocks, in which the metal organic core is retained during the reac tion, are scarce. 5 As a rule, cross linking of polynuclear complexes (blocks) by bridging ligands results in nonpo rous structures. 6-8 Thus, the preparation of PCP where the basic structure of polynuclear blocks would be retained is topical. In this case, the physical properties of a polynu clear complex (for example, magnetic and spectral) will, at least partially, predetermine the properties of the result ing coordination polymer, which will allow obtaining the compounds with the desired properties.The aim of the present work was to study a possibility of using the polynuclear complexes with homonuclear (Mn 6 O 2 ) and heteronuclear (Fe 2 MO, where M = Co, Ni) cores for the preparation of PCP by cross linking with conformationally rigid ligands (4,4´ bipyridine (bpy)...

2D Porous Honeycomb Polymers versus Discrete Nanocubes from Trigonal Trinuclear Complexes and Ligands with Variable Topology

“…• metalorganic frameworks • microporous materials • nanostructures • solidstate structures ty compared to other polynuclear carboxylates, which has allowed it to avoid destruction or re-arrangement in reactions with organic linkers. [6,7] Trisubstituted pyridines 2,4,6-tris(4pyridyl)pyridine (L1) and 4-(4-N,N-dimethylaminophenyl)-2,6-bis(4-pyridyl)pyridine (L2; Figure 1) were used as bridging ligands. Ligand L1 could be considered as a pseudo-D 3h block: it could bind to three metal ions through the three 4pyridyl groups, whilst the N atom in the central ring was not coordinated to the metal ions (it was impossible to distinguish it from carbon atoms).…”

Versatile Reactivity of MnII Complexes in Reactions with N-Donor Heterocycles: Metamorphosis of Labile Homometallic Pivalates vs. Assembling of Endurable Heterometallic Acetates

“…Synthesis of compounds [M 3 O(RCO 2 ) 6 (4,4′-bipy) 3 ] 0/+ which can potentially bind metal ions was reported earlier [ 59 ]. In contrast to the reaction of [Fe 2 MO(OAc) 6 (H 2 O) 3 ] (M = Co, Ni) with 4,4′-bipy which led to destruction of the trinuclear blocks or to the formation of porous [MFe 2 O(OAc) 6 (4,4′-bipy) 1.5 ] n coordination polymers [ 27 ], compound [Fe 2 MO(OAc) 6 (H 2 O) 3 ] was stable under the same conditions and formed coordination polymers with a ratio of trinuclear block to bridging ligand equal to 1:1 or 1:2.…”

“…In the majority of these applications the stability or reactivity of the polynuclear core play an important role. In many cases polynuclear complexes undergo rearrangement or dissociation in solution because of instability in solvent or upon interaction with the “additional” ligands [ 21 , 22 , 23 , 24 , 25 , 26 , 27 ], and the resulting compounds may contain a metal core different from the one existing in the starting complex. Such rearrangement reactions lead to the formation of certain polynuclear cores, which are most stable under the reaction conditions.…”

Synthesis and characterization of four novel manganese(II) chains formed by 4,4′-azobis(pyridine) and benzoate or nitrobenzoates: Stabilization of unusual ladder structures

“…Albeit, the number of Mn(II) complexes with a ladder structure is quite limited. As far as we know, only three very similar structures, formed by acetate [57] or o-nitro benzoate [49] and 4,4 0 -bipy, and benzoate and l 2 -1,2-bis(4-pyridyl) ethylene [58] have been reported. Among them only the compound which is formed by onitro benzoate and 4,4 0 -bipy has been characterized both structurally and magnetically.…”