Coordination Cluster Analogues of the High‐Spin [Mn₁₉] System with Functionalized 2,6‐Bis(hydroxymethyl)phenol Ligands

Abstract

A series of 2,6‐bis(hydroxymethyl)‐4‐R‐phenol ligands (H3LR; R = H, F, Cl, Br, I, Ph, NH2, NO2, SMe) have either been newly synthesized or the existing syntheses have been significantly improved to investigate ligand‐functionalized analogues of the previously published coordination cluster [MnIII12MnII7(μ4‐O)8(μ3‐N3)8(HLMe)12(MeCN)6]Cl2·10MeOH·MeCN (1) with S = 83/2. The crystal structures and magnetic properties of three such Mn19 clusters, namely, [MnIII12MnII7(μ4‐O)8(HLH)12(μ3‐Cl)7(μ3‐OMe)(MeOH)6]Cl2·16H2O·10MeOH·MeCN (3), [MnIII12MnII7(μ4‐O)8(HLI)12(μ3‐N3)8(MeOH)6](O2CH)2·16MeOH·10MeCN (4) and [MnIII12MnII7(μ4‐O)8(μ3‐Cl)7.7(μ3‐OMe)0.3(HLSMe)12(MeOH)6]Cl2·27MeOH (5) are reported and compared to those of the parent cluster. When these ligands are functionalized with substituents of moderate electronegativity, it is possible to synthesize Mn19 analogues; however, when such ligands bear highly electron‐donating (amino) or ‐withdrawing (nitro) substituents, the Mn19 analogues are no longer accessible. The Mn19 cluster framework is both magnetically and structurally robust with respect to the electron‐donor/acceptor characteristics of the ligand substituent; therefore, the Mn19 system is an excellent platform for peripheral chemical engineering.

Influence of Mn/Ca ratio in Mn-Ca coordination clusters: Synthesis, structure, and magnetic characterisation

“…Compound 3 crystallises in the trigonal space group R-3 with Z = 3, isotypically to the previously reported [Mn 19 ] and [Mn 18 M] coordination clusters (Fig. 3) [20][21][22][23][24][25]. The metallic content of 3 however differs from that of the previously reported [Mn 18 M] compounds, in that in addition to the clean replacement of the central eight-coordinate Mn II by Ca 2+ , five of the six "outer" seven-coordinate Mn II ions have been replaced by Ca 2+ ions, Fig.…”

“…For some time now, we have been exploring the use of the H 3 L R ligand system based on 2,6-bis(hydroxymethyl)-4-R-phenol (R = H, Me, I, F, OMe, SMe) and successfully developed reproducible routes for the syntheses of homometallic [Mn 19 ], complex 1, (Fig. 1) and/or heterobimetallic Mn 18 M (M = Cd, Sr, Dy, Lu, Y) aggregates [20][21][22][23][24][25]. The [Mn 18 M] compounds were obtained through the targeted replacement of the central Mn II in 1 with the heterometal ion, M n+ , which could be achieved by the simple addition of the corresponding metal salt to the reaction mixture that afforded 1.…”

Synthesis of new Mn19 analogues and their structural, electrochemical and catalytic properties

“…Previously, we have demonstrated that depending on the reactants, the face-bridging ligands of the Mn19 system can either be N3, Br, Cl, OMe or OH. [9][10][11][12][13][14] Herein, refluxing a mixture of H3L Me and MnBr2•4H2O in the presence of Et3N in MeCN/MeOH (5/1, v/v) afforded [Mn III 12Mn II 7(μ4-O8(μ3-OCH3)2(μ3-Br)6(HL Me )12(MeOH)6]Br2 (2). When a similar reaction was carried out with MnCl2•4H2O as source of Mn and in the additional presence of Sr(NO3)2, the compound [Mn III 12Mn II 6Sr(μ4-O8(μ3-Cl)8(HL Me )12(MeCN)6]Cl2 (3) was obtained.…”

“…2,3 For some time now, we have developed a variety of homo-and hetero-metallic Mn clusters using phosphonate ligands, [4][5][6][7][8] and the H3L R ligand system based on 2,6-bis(hydroxymethyl)-4-Rphenol (where R is the substituent at the 4-position). [9][10][11][12][13][14] Among others, we are particularly interested in the coordination chemistry of the H3L R ligand system because of the variable modes (µ2 or µ3) of coordination provided by this oxido-rich molecule that leads to the isolation of organic-inorganic hybrid architectures with multiple metal centres. To this end, we have successfully developed reproducible routes for the syntheses of homometallic Mn19(R) (R = H, Me, I, F, OMe, SMe) [9][10][11][12] and/or heterobimetallic Mn18M (M = Cd, Sr, Dy, Lu, Y) aggregates 13,14 using this ligand system.…”

“…[9][10][11][12][13][14] Among others, we are particularly interested in the coordination chemistry of the H3L R ligand system because of the variable modes (µ2 or µ3) of coordination provided by this oxido-rich molecule that leads to the isolation of organic-inorganic hybrid architectures with multiple metal centres. To this end, we have successfully developed reproducible routes for the syntheses of homometallic Mn19(R) (R = H, Me, I, F, OMe, SMe) [9][10][11][12] and/or heterobimetallic Mn18M (M = Cd, Sr, Dy, Lu, Y) aggregates 13,14 using this ligand system. The Mn19 and Mn18M systems represent a family of materials with attractive structural and magnetic properties which may open new gateways to coordination complexes exhibiting a broad range of physicochemical properties appropriate for developing applications in data storage, 15 catalysis, 16 piezoelectricity, 17 and superconductivity.…”