Supramolecular Mn(II) and Mn(II)/Mn(III) Grid Complexes with [Mn₉(μ₂-O)₁₂] Core Structures. Structural, Magnetic, and Redox Properties and Surface Studies

A series of [3 × 3] Mn(II)9, antiferromagnetically coupled, alkoxide-bridged, square grid complexes, derived from a group of “tritopic” dihydrazide ligands, is described. The outer ring of eight Mn(II) centers in the grids is isolated magnetically from the central Mn(II) ion, leading to an S = 0 ground state for the ring, and an S = 5/2 ground state overall in each case. Exchange in the Mn(II)8 ring can be represented by a 1D chain exchange model. Rich electrochemistry displayed by these systems has led to the production of Mn(II)/Mn(III) mixed-oxidation-state grids by both electrochemical and chemical means. Structures are reported for [Mn9(2poap)6](C2N3)6·10H2O (1), [Mn9(2poap)6]2[Mn(NCS)4(H2O)]2(NCS)8·10H2O (2), [Mn9(2poapz)6](NO3)6·14.5H2O (3), [Mn9(2popp)6](NO3)6·12H2O (4), [Mn9(2pomp)6](MnCl4)2Cl2·2CH3OH·7H2O (5), and [Mn9(Cl2poap)6](ClO4)9·7H2O (6). Compound 1 crystallized in the tetragonal system, space group P42/n, with a = 21.568(1) Å, c = 16.275(1) Å, and Z = 2. Compound 2 crystallized in the triclinic system, space group P1̄, with a = 25.043(1) Å, b = 27.413(1) Å, c = 27.538(2) Å, α = 91.586(2)°, β = 113.9200(9)°, γ = 111.9470(8)°, and Z = 2. Compound 3 crystallized in the triclinic system, space group P1̄, with a = 18.1578(12) Å, b = 18.2887(12) Å, c = 26.764(2) Å, α = 105.7880(12)°, β = 101.547(2)°, γ = 91.1250(11)°, and Z = 2. Compound 4 crystallized in the tetragonal system, space group P41212, with a = 20.279(1) Å, c = 54.873(6) Å, and Z = 4. Compound 5 crystallized in the tetragonal system, space group I4̄, with a = 18.2700(2) Å, c = 26.753(2) Å, and Z = 2. Compound 6 crystallized in the triclinic system, space group P1̄, with a = 19.044(2) Å, b = 19.457(2) Å, c = 23.978(3) Å, α = 84.518(3)°, β = 81.227(3)°, γ = 60.954(2)°, and Z = 2. Preliminary surface studies on Au(111), with a Mn(II) grid complex derived from a sulfur-derivatized ligand, indicate monolayer coverage via gold−sulfur interactions, and the potential for information storage at high-density levels.