Iron(III)‐Pivalate‐Based Complexes with Tetranuclear {Fe₄(μ₃‐O)₂}⁸⁺ Cores and N‐Donor Ligands: Formation of Cluster and Polymeric Architectures

Abstract

8 (hmta)] n (2) (bpm = 2,2Ј-bipyrimidine and hmta = hexamethylenetetramine). For cluster 1, two structural isomers, 1a and 1b·3MeCN, have been found. X-ray crystallographic analysis showed that all complexes consist of a central {Fe 4 (μ 3 -O) 2 } 8+ core. In 1a, metal ions in the core are additionally linked by six bridging pivalates as two other pivalates and a bpm ligand are chelated to Fe III ions, whereas in

Cluster-Based Networks: 1D and 2D Coordination Polymers Based on {MnFe2(μ3-O)}-Type Clusters

“…Dark green crystals suitable for X-ray analysis were filtered off the next day, washed with npropanol and acetonitrile, and dried in air (yield 0. 15…”

“…Recently, we have reported the synthesis and characterization of one-dimensional manganese chain coordination polymers composed of carboxylate cluster blocks with {Mn 3 O}, {Mn 4 O 2 }, and {Mn 6 O 2 } metallic cores bridged by N-donor ligands and iron chain coordination polymers consisting of the pivalate cluster building units with a {Fe 4 O 2 } metallic core and hmta linkers . In a continuation of this work, we present here convenient synthetic routes to new one- and two-dimensional heterometallic Mn–Fe coordination polymers which are based on the use of mixed-valent μ 3 -oxo trinuclear manganese(II/III) pivalate clusters, [Mn 3 O(O 2 CCMe 3 ) 6 (hmta) 3 ]·(solvent) (hmta = hexamethylenetetramine; solvent = n -propanol ( 1 ), toluene ( 2 )) and the homovalent μ 3 -oxo trinuclear iron(III) pivalate cluster [Fe 3 O(O 2 CCMe 3 ) 6 (H 2 O) 3 ]O 2 CCMe 3 ·2Me 3 CCO 2 H. The resulting network structures include one-dimensional chains in {[MnFe 2 O(O 2 CCMe 3 ) 6 (hmta) 2 ]·0.5MeCN} n ( 3 ) and {[MnFe 2 O(O 2 CCMe 3 ) 6 (hmta) 2 ]·Me 3 CCO 2 H·( n -hexane)} n ( 4 ) and two-dimensional layers in {[MnFe 2 O(O 2 CCMe 3 ) 6 (hmta) 1.5 ]·(toluene)} n ( 5 ).…”

“…Recently, we have reported the synthesis and characterization of one-dimensional manganese chain coordination polymers composed of carboxylate cluster blocks with {Mn 3 O}, 13 {Mn 4 O 2 }, 13 and {Mn 6 O 2 } 14 metallic cores bridged by Ndonor ligands and iron chain coordination polymers consisting of the pivalate cluster building units with a {Fe 4 O 2 } metallic core and hmta linkers. 15 In a continuation of this work, we present here convenient synthetic routes to new one-and twodimensional heterometallic Mn−Fe coordination polymers which are based on the use of mixed-valent μ 3 -oxo trinuclear m a n g a n e s e ( I I / I I I ) p i v a l a t e c l u s t e r s , [ M n 3 O -(O 2 CCMe 3 ) 6 (hmta) 3 ]•(solvent) (hmta = hexamethylenetetramine; solvent = n-propanol (1), toluene (2)) and the homovalent μ 3 -oxo trinuclear iron(III…”

Cluster-Based Coordination Polymers of Mn/Fe-Oxo Pivalates and Isobutyrates

“…The temperature dependence of χT in 7 indicates dominant antiferromagnetic interactions inside the {Mn4} units with a value of 13.46 cm 3 K mol −1 at 300 K that is close to the value expected for an uncoupled {Mn II 2Mn III 2} system (χT = 14.75 cm 3 K mol −1 for g = 2.00). The first tetranuclear {Fe4O2}-based coordination polymer [Fe4O2(piv)8(hmta)]n (8) reported in 2011 by Baca and coworkers [43] was isolated from the reaction of the μ3-oxo trinuclear pivalate complex [Fe3O(piv)6(H2O)3]piv•2(Hpiv) with hmta in MeCN. In 8, tetranuclear [Fe4(μ3-O)2(piv)8] clusters are bridged by hmta ligands forming zigzag chains ( Figure 5).…”

Avoiding Magnetochemical Overparametrization, Exemplified by One-Dimensional Chains of Hexanuclear Iron(III) Pivalate Clusters

“…The rational preparation of such CPs, in particular the controlled integration of the individual cluster properties into those of the final, networked system, represents multiple challenges. Taking advantage of the iron(III) and manganese(II,III) polynuclear carboxylate clusters in the preparation of magnetic coordination polymers, we reported a large variety of cluster-based CPs where building cluster blocks range from tri- and tetranuclear carboxylate clusters (for Fe- and Mn-containing CPs) to hexanuclear carboxylate clusters (for Mn-containing CPs). − The interpretation of the magnetic characteristics of CPs based on microscopic model Hamiltonians is, however, complicated by the additional intercluster coupling. While this can be accounted for by several models, e.g., the molecular-field approach, adding even one additional independent parameter to the fitting procedure that relates the experimental magnetic data to the model Hamiltonian can result in isospectrality issues, i.e., in multiple sets of model parameters that all result in virtually identical quality-of-fit indicators.…”