Heptanuclear and Decanuclear Manganese Complexes with the Anion of 2-Hydroxymethylpyridine

Abstract

The synthesis and magnetic properties are reported of two new clusters [Mn(10)O(4)(OH)(2)(O(2)CMe)(8)(hmp)(8)](ClO(4))(4) (1) and [Mn(7)(OH)(3)(hmp)(9)Cl(3)](Cl)(ClO(4)) (2). Complex 1 was prepared by treatment of [Mn(3)O(O(2)CMe)(6)(py)(3)](ClO(4)) with 2-(hydroxymethyl)pyridine (hmpH) in CH(2)Cl(2), whereas 2 was obtained from the reaction of MnCl(2).4H(2)O, hmpH, and NBu(n)(4)MnO(4) in MeCN followed by recrystallization in the presence of NBu(n)(4)ClO(4). Complex 1.2py.10CH(2)Cl(2).2H(2)O crystallizes in the triclinic space group P1. The cation consists of 10 Mn(III) ions, 8 mu(3)-O(2)(-) ions, 2 mu(3)-OH(-) ions, 8 bridging acetates, and 8 bridging and chelating hmp(-) ligands. The hmp(-) ligands bridge through their O atoms in two ways: two with mu(3)-O atoms and six with mu(2)-O atoms. Complex 2.3CH(2)Cl(2).H(2)O crystallizes in the triclinic space group P1. The cation consists of four Mn(II) and three Mn(III) ions, arranged as a Mn(6) hexagon of alternating Mn(II) and Mn(III) ions surrounding a central Mn(II) ion. The remaining ligation is by three mu(3)-OH(-) ions, three terminal chloride ions, and nine bridging and chelating hmp(-) ligands. Six hmp(-) ligands contain mu(2)-O atoms and three contain mu(3)-O atoms. The Cl(-) anion is hydrogen-bonded to the three mu(3)-OH(-) ions. Variable-temperature direct current (dc) magnetic susceptibility data were collected for complex 1 in the 5.00-300 K range in a 5 kG applied field. The chi(M)T value gradually decreases from 17.87 cm(3) mol(-1) K at 300 K to 1.14 cm(3) mol(-1) K at 5.00 K, indicating an S = 0 ground state. The ground-state spin of complex 2 was established by magnetization measurements in the 0.5-3.0 T and 1.80-4.00 K ranges. Fitting of the data by matrix diagonalization, incorporating only axial anisotropy (DS(z)(2)), gave equally good fits with S = 10, g = 2.13, D = -0.14 cm(-1) and S = 11, g = 1.94, D = -0.11 cm(-1). Magnetization versus dc field scans down to 0.04 K reveal no hysteresis attributable to single-molecule magnetism behavior, only weak intermolecular interactions.

Phenyl 2‐Pyridyl Ketone and Its Oxime in Manganese Carboxylate Chemistry: Synthesis, Characterisation, X‐ray Studies and Magnetic Properties of Mononuclear, Trinuclear and Octanuclear Complexes

“…[15] It is also likely, as with many other reactions in higher oxidation state Mn chemistry, that the reaction solution contains a complicated mixture of several species in equilibrium, with factors such as relative solubility, lattice energies, crystallisation kinetics and others determining the identity of the isolated product. [16] Comproportionation reactions between Mn II and Mn VII sources have found extensive use to produce Mn/O 2Ϫ /RCO 2 Ϫ clusters of various nuclearities. [15,16] Complex 2 was isolated from the above reaction solution in 55% yield.…”

“…[16] Comproportionation reactions between Mn II and Mn VII sources have found extensive use to produce Mn/O 2Ϫ /RCO 2 Ϫ clusters of various nuclearities. [15,16] Complex 2 was isolated from the above reaction solution in 55% yield. In an attempt to increase further the yield of the product, the Mn II /MnO 4 Ϫ ratio was increased to that which would give an average Mn oxidation state of ϩ2.5, as found in 2, but this instead led to crystallisation of [Mn 6 O 2 [17b] containing 4Mn II , 2Mn III , and no bound (ph)(2-py)CNO Ϫ groups.…”

“…Complex 2 is also one of the rare examples of polynuclear Mn complexes that contain oxo and hydroxo bridges simultaneously, [29] other such complexes being [Mn 8 O 4 (OH) 2 (O 2 CMe) 12 (DMHP) 2 (py) 2 ] (DMHP ϭ 2,6-dimethyl-6-hydroxypyrimidine; py ϭ pyridine), [26] [Mn 4 O 5 [30] and [Mn 10 O 4 4 [hmp ϭ the anion of 2-(hydroxymethyl)pyridine]. [16] six edge-sharing triangles or three [27b] edge-sharing ''butterfly'' units (ladder-like unit) [Mn 8 O 4 two butterfly-like cores arranged [27d] face-to-face and bridged by two bis-bidentate L ligands [Mn 8 O 10 [28] fused to give a core with a serpentine topology [a] Counterions and solvate molecules omitted; bpe ϭ trans-1, 2-bis(4-pyridyl)ethene; bpy ϭ 2,2Ј-bipyridine; dbm ϭ the anion of dibenzoylmethane; DMHP ϭ 2,6-dimethyl-6-hydroxypyrimidine; Et 2 mal ϭ the dianion of 2,2-diethylmalonic acid; L ϭ the dianion of (6-hydroxymethylpyridin-2-yl)-(6-hydroxymethylpyridin-2-yl methoxymethanol); LЈ ϭ 1,2-bis(5-methyl-2,2Ј-bipyridyl-5-yl)ethane; pic ϭ the picolinate anion; piv ϭ the pivalate anion; py ϭ pyridine.…”

“…[4] The first single-molecule magnet (SMM) was [Mn 12 O 12 (O 2 CMe) 16 (H 2 O) 4 ], which possesses an S ϭ10 ground state, [5] and a number of other Mn x carboxylate SMMs have since been discovered. [4,6] There is thus a continuing need to develop new synthetic methods for the preparation of new polynuclear Mn carboxylate compounds.…”

Crystal structure of tetrakis(6-methylpyridin-2-yl)methanolato-κ3O,N:O' dicopper(II), C28H34Cu2N6O10

“…These simple pyridine alcohols are of particular interest. Not only they can form various structural topologies through aversatile N,Ochelating and -bridging group, but also their alkoxide arm usually supports ferromagnetic coupling between the metal atomsi t bridges and mayresult in alarge Svalue, which is one of the necessary requirements for molecules presenting the behavior of single-molecule magnetism [4][5][6][7][8][9][10].I nthis paper, we report anovel dimer Cu(II) complex. The symmetrical coordination of this complex consists of two Cu(II) centers surrounded by four 6-Mehmpligands and isolated NO 3 -anions.…”