High-nuclearity Ce/Mn and Th/Mn cluster chemistry: preparation of complexes with [Ce4Mn10O10(OMe)6]18+ and [Th6Mn10O22(OH)2]18+ cores

The syntheses, structures, and magnetic properties are reported of the mixed-metal complexes [Ce4Mn10O10(OMe)6(O2CPh)16(NO3)2(MeOH)2(H2O)2] (1) and [Th6Mn10O22(OH)2(O2CPh)16-(NO3)2(H2O)8] (2), which were both prepared by the reaction of (NBun4)[Mn4O2(O2CPh)9(H2O)] (3) with a source of the heterometal in MeCN/MeOH. Complexes 1 and 2 crystallize in the monoclinic space group C2/c and the triclinic space group P, respectively. Complex 1 consists of 10 MnIII, 2 CeIII, and 2 CeIV atoms and possesses a very unusual tubular [Ce4Mn10O10(OMe)6]18+ core. Complex 2 consists of 10 MnIV and 6 ThIV atoms and possesses a [Th6Mn10O22(OH)2]18+ core with the metal atoms arranged in layers with a 2:3:6:3:2 pattern. Peripheral ligation around the cores is provided by 16 bridging benzoates, 2 chelating nitrates, and either (i) 2 each of terminal H2O and MeOH groups in 1 or (ii) 8 terminal H2O groups in 2. Complex 1 is the largest mixed-metal Ce/Mn cluster and the first 3d/4f cluster with mixed-valency in its lanthanide component, while complex 2 is the first Th/Mn cluster and the largest mixed transition metal/actinide cluster to date. Solid-state dc and ac magnetic susceptibility measurements on 1 and 2 establish that they possess S = 4 and 3 ground states, respectively. Ac susceptibility studies on 1 revealed nonzero frequency-dependent out-of-phase (chiM' ') signals at temperatures below 3 K; complex 2 displays no chiM' ' signals. However, single-crystal magnetization vs dc field scans at variable temperatures and variable sweep-rates down to 0.04 K on 1 revealed no noticeable hysteresis loops, except very minor ones at 0.04 K assignable to weak intermolecular interactions propagated by hydrogen bonds involving CeIII-bound ligands. Complex 1 is thus concluded not to be a single-molecule magnet (SMM), and the combined results thus represent a caveat against taking such ac signals as sufficient proof of a SMM.     

Di-2-pyridyl ketone oxime [(py)2CNOH] in manganese carboxylate chemistry: mononuclear, dinuclear and tetranuclear complexes, and partial transformation of (py)2CNOH to the gem-diolate(2-) derivative of di-2-pyridyl ketone leading to the formation of NO3-

The use of di-2-pyridyl ketone oxime, (py)2CNOH, in manganese carboxylate chemistry has been investigated. Using a variety of synthetic routes complexes [Mn(O2CPh)2{(py)2CNOH}2].0.25H2O (1.0.25H2O), Mn4(O2CPh)2{(py)2CO2}2{(py)2CNO}2Br2].MeCN (2.MeCN), [Mn4(O2CPh)2{(py)2CO2}2{(py)2CNO}2Cl(2)].2MeCN (3.2MeCN), [Mn4(O2CMe)2{(py)2CO2}2{(py)2CNO}2Br2].2MeCN (4.2MeCN), [Mn4(O2CMe)2{(py)2CO2}2{(py)2CNO}2(NO3)2].MeCN.H2O (5.MeCN.H2O) and [Mn2(O2CCF3)2(hfac)2{(py)2CNOH}2] (6) have been isolated in good yields. Remarkable features of the reactions are the in situ transformation of an amount of (py)2CNOH to yield the coordination dianion, (py)2CO2(2-), of the gem-diol derivative of di-2-pyridyl ketone in 2-5, the coordination of nitrate ligands in 5 although the starting materials are nitrate-free and the incorporation of CF3CO2- ligands 6 in which was prepared from Mn(hfac)(2).3H2O (hfac(-)= hexafluoroacetylacetonate). Complexes 2-4 have completely analogous molecular structures. The centrosymmetric tetranuclear molecule contains two MnII and two MnIII six-coordinate ions held together by four mu-oxygen atoms from the two 3.2211 (py)2CO2(2-) ligands to give the unprecedented [MnII(mu-OR)MnIII(mu-OR)2MnIII(mu-OR)MnII]6+ core consisting of a planar zig-zag array of the four metal ions. Peripheral ligation is provided by two 2.111 (py)2CNO-, two 2.11 PhCO2- and two terminal Br- ligands. The overall molecular structure 5 of is very similar to that of 2-4 except for the X- being chelating NO3-. A tentative reaction scheme was proposed that explains the observed oxime transformation and nitrate generation. The CF3CO2- ligand is one of the decomposition products of the hfac- ligand. The two Mn(II) ions are bridged by two neutral (py)2CNOH ligands which adopt the 2.0111 coordination mode. A chelating hfac- ligand and a terminal CF3CO2- ion complete a distorted octahedral geometry at each metal ion. The CV of complex reveals irreversible reduction and oxidation processes. Variable-temperature magnetic susceptibility studies in the 2-300 K range for the representative tetranuclear clusters 2 and 4 reveal weak antiferromagnetic exchange interactions, leading to non-magnetic ST = 0 ground states. Best-fit parameters obtained by means of the program CLUMAG and applying the appropriate Hamiltonian are J(Mn(II)Mn((III))=-1.7 (2), -1.5 (4) cm(-1) and J(Mn(III)Mn(III))=-3.0 (2, 4) cm(-1).     

A family of manganese rods: syntheses, structures, and magnetic properties

The reaction of the mixed-valent metal triangles [Mn(3)O(O(2)CR)(6)(py)(3)] (R = CH(3), Ph, C(CH(3))(3)) with the tripodal ligands H(3)thme (1,1,1-tris(hydroxymethyl)ethane) and H(3)tmp (1,1,1-tris(hydroxymethyl)propane) in MeCN, produces a family of manganese rodlike complexes whose structures are all derived from a series of edge-sharing triangles. Variable temperature direct current (dc) magnetic susceptibility data were collected for all complexes in the 1.8-300 K temperature range in fields up to 7.0 T. Complex 1, [Mn(12)O(4)(OH)(2)(PhCOO)(12)(thme)(4)(py)(2)], has an S = 7 ground state with the parameters g = 1.98 and D = -0.13 K. Complex 2, [Mn(8)O(4)((CH(3))(3)CCO(2))(10)(thme)(2)(py)(2)] has a ground state of S = 6, with g = 1.81 and D = -0.36 K. Complex 3, [Mn(7)O(2)(PhCO(2))(9)(thme)(2)(py)(3)], has a spin ground states of S = 7 with the parameters g = 1.78 and D = -0.20 K. The best fit for complex 4, [Mn(6)((CH(3))(3)CCO(2))(8)(tmp)(2)(py)(2)], gave a spin ground state of S = 3 with the parameters g = 1.73 and D = -0.75 K, but was of poorer quality than that normally obtained. The presence of multiple Mn(2+) ions in the structure of 4 leads to the presence of low-lying excited states with energy levels very close to the ground state, and in the case of complex 5, [Mn(6)(CH(3)CO(2))(6)(thme)(2)(H(2)tea)(2)], no satisfactory fit of the data was obtained. DFT calculations on 4 and 5 indicate complexes with spin ground states of S = 4 and S = 0 respectively, despite their topological similarities. Single-crystal hysteresis loop and relaxation measurements show complex 1 to be a SMM.     

Single-molecule magnets: a family of MnIII/CeIV complexes with a [Mn8CeO8]12+ core

Four heterometallic, enneanuclear Mn8Ce clusters [Mn8CeO8(O2CMe)12(H2O)4] (4), [Mn8CeO8(O2CMe)12(py)4] (5), [Mn8CeO8(O2CPh)12(MeCN)4] [Mn8CeO8(O2CPh)12(dioxane)4] (6), and [Mn8CeO8(O2CCHPh2)12(H2O)4] (7) have been prepared by various methods. Their cores are essentially isostructural and comprise a nonplanar, saddlelike [MnIII8O8]8+ loop containing a central CeIV ion attached to the eight micro3-O2- ions. Peripheral ligation around the [Mn8CeO8]12+ core is provided by eight micro- and four micro3-O2CR- groups. Terminal ligation on four MnIII atoms is provided by H2O in 4 and 7, pyridine in 5, and MeCN/dioxane in 6. Solid-state magnetic susceptibility studies, fits of dc magnetization vs field and temperature data, and in-phase ac susceptibility studies in a zero dc field have established that complexes 4, 5, and 7 possess S=16, S=4 or 5, and S=6+/-1 spin ground states, respectively, but in all cases there are very low-lying excited states. The large variation in the ground-state spins for this isostructural family is rationalized as due to a combination of weak exchange interactions between the constituent MnIII atoms, and the presence of both nearest-neighbor and next-nearest-interactions of comparable magnitudes. Magnetization vs applied dc field sweeps on single crystals of 4.4H2O and 7.4H2O.3MeCN.2CH2Cl2 down to 0.04 K have established that these two complexes are new single-molecule magnets (SMMs). The former also shows an exchange-bias, a perturbation of its single-molecule properties from very weak intermolecular interactions mediated by hydrogen-bonding interactions with lattice-water molecules of crystallization.     

Single-molecule magnets: a new class of tetranuclear manganese magnets

The preparation, X-ray structure, and detailed physical characterization are presented for a new type of single-molecule magnet [Mn4(O2CMe)2(pdmH)6](ClO4)2 (1). Complex 1.2MeCN.Et2O crystallizes in the triclinic space group P1, with cell dimensions at 130 K of a = 11.914(3) A, b = 15.347(4) A, c = 9.660(3) A, alpha = 104.58(1) degree, beta = 93.42(1) degree, gamma = 106.06(1) degree, and Z = 1. The cation lies on an inversion center and consists of a planar Mn4 rhombus that is mixed-valent, MnIII2MnII2. The pdmH- ligands (pdmH2 is pyridine-2,6-dimethanol) function as either bidentate or tridentate ligands. The bridging between Mn atoms is established by either a deprotonated oxygen atom of a pdmH- ligand or an acetate ligand. The solvated complex readily loses all acetonitrile and ether solvate molecules to give complex 1, which with time becomes hydrated to give 1.2.5H2O. Direct current and alternating current magnetic susceptibility data are given for 1 and 1.2.5H2O and indicate that the desolvated complex has a S = 8 ground state, whereas the hydrated 1.2.5H2O has a S = 9 ground state. Ferromagnetic interactions between MnIII-MnII and MnIII-MnIII pairs result in parallel spin alignments of the S = 5/2 MnII and S = 2 MnIII ions. High-frequency EPR spectra were run for complex 1.2.5H2O at frequencies of 218, 328, and 436 GHz in the 4.5-30 K range. A magnetic-field-oriented polycrystallite sample was employed. Fine structure is clearly seen in this parallel-field EPR spectrum. The transition fields were least-squares-fit to give g = 1.99, D = -0.451 K, and B4 degrees = 2.94 x 10(-5) K for the S = 9 ground state of 1.2.5H2O. A molecule with a large-spin ground state with D < 0 can function as a single-molecule magnet, as detected by techniques such as ac magnetic susceptibility. Out-of-phase ac signals (chi' M) were seen for complexes 1 and 1.2.5H2O to show that these complexes are single-molecule magnets. A sample of 1 was studied by ac susceptibility in the 0.4-6.4 K range with the ac field oscillating at frequencies in the 1.1-1000 Hz range. A single peak in chi' M vs temperature plots was seen for each frequency; the temperature of the chi' M peak varies from 2.03 K at 995 Hz to 1.16 K at 1.1 Hz. Magnetization relaxation rates were evaluated in this way. An Arrhenius plot gave an activation energy of 17.3 K, which, as expected, is less than the 22.4 K value calculated for the thermodynamic barrier for magnetization direction reversal for an S = 8 complex with D = -0.35 K. The 1.2.5H2O complex with an S = 9 ground state has its chi' M peaks at higher temperatures.     

New routes to high nuclearity cages: dimerisation of a manganese triangle via solvothermal synthesis

Heating [Mn3O(O2CPh)6(py)2(H2O)] in MeCN at 100 degrees C for 12 hours in a sealed Teflon container produces the hexanuclear species [Mn6O2(O2CPh)12(py)2]: dimerisation of the triangle occurs via solvent loss and ligand rearrangement.     

Tetranuclear manganese carboxylate complexes with a trigonal pyramidal metal topology via controlled potential electrolysis

Controlled potential electrolysis (CPE) procedures are described that provide access to complexes with a [Mn4(mu 3-O)3(mu 3-O2CR)]6+ core (3MnIII,MnIV) and a trigonal pyramidal metal topology, starting from species containing the [Mn4(mu 3-O)2]8+ core (4MnIII). [Mn4O2(O2CMe)6(py)2(dbm)2] (6): triclinic, P1, a = 10.868(3) A, b = 13.864(3) A, c = 10.625(3) A, alpha = 108.62(1) degrees, beta = 118.98(1) degrees, gamma = 89.34(2) degrees, V = 1307 A3, Z = 1, T = -131 degrees C, R (Rw) = 3.24 (3.70)%. [Mn4O2(O2CPh)6(py)(dbm)2] (8): monoclinic, P2(1)/c, a = 14.743(6) A, b = 15.536(8) A, c = 30.006(13) A, beta = 102.79(1) degrees, V = 6702 A3, Z = 4, T = -155 degrees C, R (Rw) = 4.32 (4.44)%. Both 6 and 8 contain a [Mn4O2]8+ core; 8 only has one py group, the fourth MnIII site being five-coordinate. (NBun4)[Mn4O2(O2CPh)7(dbm)2] (10) is available from two related procedures. CPE of 10 at 0.65 V vs ferocene in MeCN leads to precipitation of [Mn4O3(O2CPh)4(dbm)3] (11); similarly, CPE of 6 at 0.84 V in MeCN/CH2Cl2 (3:1 v/v) gives [Mn4O3(O2CMe)4(dbm)3] (12). Complex 11: monoclinic, P2(1)/n, a = 15.161(3) A, b = 21.577(4) A, c = 22.683(5) A, beta = 108.04(3) degrees, V = 7056 A3, Z = 4, T = -100 degrees C, R (wR2) = 8.63 (21.80)%. Complex 12: monoclinic, P2(1)/n, a = 13.549(2) A, b = 22.338(4) A, c = 16.618(2) A, beta = 103.74(1) degrees, V = 4885 A3, Z = 4, T = -171 degrees C, R (Rw) = 4.63 (4.45)%. Both 11 and 12 contain a [Mn4(mu 3-O)3(mu-O2CR)] core with a Mn4 trigonal pyramid (MnIV at the apex) and the RCO2- bridging the MnIII3 base. However, in 11, the carboxylate is eta 2,mu 3 with one O atom terminal to one MnIII and the other O atom bridging the other two MnIII ions, whereas in 12 the carboxylate is eta 1,mu 3, a single O atom bridging three MnIII ions. Variable-temperature, solid-state magnetic susceptibility studies on 11 and 12 show that, for both complexes, there are antiferromagnetic exchange interactions between MnIII/MnIV pairs, and ferromagnetic interactions between MnIII/MnIII pairs. In both cases, the resultant ground states of the complex is S = 9/2, confirmed by magnetization vs field studies in the 2.00-30.0 K and 0.50-50 kG temperature and field ranges, respectively.     

Single-molecule magnets: structure and properties of [Mn18O14(O2CMe)18(hep)4(hepH)2(H2O)2](ClO4)2 with spin S = 13

The reaction of 2-(hydroxyethyl)pyridine (hepH) with a 2:1 molar mixture of [Mn3O(O2CMe)6(py)3]ClO4 and [Mn3O(O2CMe)6(py)3] in MeCN afforded the new mixed-valent (16Mn(III), 2Mn(II)), octadecanuclear complex [Mn18O14(O2CMe)18(hep)4(hepH)2(H2O)2](ClO4)2 (1) in 20% yield. Complex 1 crystallizes in the triclinic space group P. Direct current magnetic susceptibility studies in a 1.0 T field in the 5.0-300 K range, and variable-temperature variable-field dc magnetization studies in the 2.0-4.0 K and 2.0-5.0 T ranges were obtained on polycrystalline samples. Fitting of magnetization data established that complex 1 possesses a ground-state spin of S = 13 and D = -0.18 K. This was confirmed by the value of the in-phase ac magnetic susceptibility signal. Below 3 K, the complex exhibits a frequency-dependent drop in the in-phase signal, and a concomitant increase in the out-of-phase signal, consistent with slow magnetization relaxation on the ac time scale. This suggests the complex is a single-molecule magnet (SMM), and this was confirmed by hysteresis loops below 1 K in magnetization versus dc field sweeps on a single crystal. Alternating current and direct current magnetization data were combined to yield an Arrhenius plot from which was obtained the effective barrier (U(eff)) for magnetization reversal of 21.3 K. Below 0.2 K, the relaxation becomes temperature-independent, consistent with relaxation only by quantum tunneling of the magnetization (QTM) through the anisotropy barrier via the lowest-energy MS = +/-13 levels of the S = 13 spin manifold. Complex 1 is thus the SMM with the largest ground-state spin to display QTM.     

Mn7O5(OR)2(O2CPh)9(terpy)] (R = Me, CH2Ph) complexes with a fused cubane/butterfly core and an S = 6 ground-state spin

Two new heptanuclear Mn clusters, [Mn7O5(OMe)2(O2CPh)9(terpy)] (1) and [Mn7O5(OCH2Ph)2(O2CPh)9(terpy)] (2), were prepared from the partial alcoholysis of the trinuclear complex [Mn3O(O2CPh)6(py)2(H2O)] (3) in the presence of terpy (terpy = 2,2':6',2' '-terpyridine). Complexes 1 and 2 crystallize in the triclinic P and the orthorhombic Pbca space groups, respectively. The clusters are both mixed valent, containing three Mn oxidation states: MnIV, 5MnIII, and MnII. The Mn ions are held together by nine doubly bridging benzoates, four mu3-O2- ions, one mu5-O2- ion, and either two mu-MeO- (1) or two mu-PhCH2O- (2) groups. The single terpy chelate in each complex is attached to the MnII ion. The core topology is novel and very unusual, comprising a cubane and a butterfly unit fused by sharing a MnIII and the mu5-O2- ion. Solid-state dc and ac magnetic susceptibility studies establish that complexes 1 and 2 both possess an S = 6 ground-state spin. Fits of variable-temperature and -field magnetization data gave S = 6, g = 1.88, and D = -0.21 cm-1 for 1 and S = 6, g = 1.86, and D = -0.18 cm-1 for 2. Single-crystal magnetization vs dc field scans down to 0.1 K for 2 show only very little hysteresis at 0.1 K.     

Quantum tunneling of magnetization in a new [Mn18]2+ single-molecule magnet with s = 13

The reaction between 2-(hydroxyethyl)pyridine (hepH) and a 2:1 molar mixture of [Mn3O(O2CMe)6(py)3](ClO4) and [Mn3O(O2CMe)6(py)3](py) in MeCN leads to isolation of [Mn18O14(O2CMe)18(hep)4(hepH)2(H2O)2](ClO4)2 (1) in 10% yield. The complex is 2MnII,16MnIII and consists of a Mn4O6 central unit to either side of which is attached a Mn7O9 unit. Magnetization data collected in the 2.0-4.0 K and 20-50 kG ranges were fit to yield S = 13, g = 1.86, and D = -0.13 cm-1 = -0.19 K, where D is the axial zero-field splitting parameter. AC susceptibility studies in the 0.04-4.0 K range at frequencies up to 996 Hz display out-of-phase (chiM' ') signals, indicative of a single-molecule magnet (SMM). Magnetization vs applied DC field scans exhibit hysteresis at <1.0 K, confirming 1 to be a SMM. DC magnetization decay data were collected on both a microcrystalline sample and a single crystal, and the combined data were used to construct an Arrhenius plot. Between 3.50 and 0.50 K, the relaxation rate is temperature-dependent with an effective barrier to relaxation (Ueff) of 14.8 cm-1 = 21.3 K. Below ca. 0.25 K, the relaxation rate is temperature-independent at 1.3 x 10-8 s-1, indicative of quantum tunneling of magnetization (QTM) between the lowest energy Ms = +/-13 levels of the S = 13 state. Complex 1 is both the largest spin and highest nuclearity SMM to exhibit QTM.     

New routes to polymetallic clusters: fluoride-based tri-, deca-, and hexaicosametallic MnIII clusters and their magnetic properties

The syntheses, structures and magnetic properties of three new MnIII clusters, [Mn26O17(OH)8(OMe)4F10(bta)22(MeOH)14(H2O)2] (1), [Mn(0O6(OH)2(bta)8(py)8F8] (2) and [NHEt3]2[Mn3O(bta)6F3] (3), are reported (bta=anion of benzotriazole), thereby demonstrating the utility of MnF3 as a new synthon in Mn cluster chemistry. The "melt" reaction (100 degrees C) between MnF(3) and benzotriazole (btaH, C6H5N3) under an inert atmosphere, followed by dissolution in MeOH produces the cluster [Mn26O17(OH)8(OMe)4F10(bta)22(MeOH)14(H2O)2] (1) after two weeks. Complex 1 crystallizes in the triclinic space group P1, and consists of a complicated array of metal tetrahedra linked by mu3-O2- ions, mu3- and mu2-OH- ions, mu2-MeO- ions and mu2-bta- ligands. The "simpler" reaction between MnF3 and btaH in boiling MeOH (50 degrees C) also produces complex 1. If this reaction is repeated in the presence of pyridine, the decametallic complex [Mn10O6(OH)2(bta)8(py)8F8] (2) is produced. Complex 2 crystallizes in the triclinic space group P1 and consists of a "supertetrahedral" [Mn(III)10] core bridged by six mu3-O2- ions, two mu3-OH- ions, four mu2-F- ions and eight mu2-bta- ions. The replacement of pyridine by triethylamine in the same reaction scheme produces the trimetallic species [NHEt3]2[Mn3O(bta)6F3] (3). Complex 3 crystallises in the monoclinic space group P2(1)/c and has a structure analogous to that of the basic metal carboxylates of general formula [M3O(RCO2)6L3]0/+, which consists of an oxo-centred metal triangle with mu2-bta- ligands bridging each edge of the triangle and the fluoride ions acting as the terminal ligands. DC magnetic susceptibility measurements in the 300-1.8 K and 0.1-7 T ranges were investigated for all three complexes. For each, the value of chi(M)T decreases with decreasing temperatures; this indicates the presence of dominant antiferromagnetic exchange interactions in 1-3. For complex 1, the low-temperature value of chi(M)T is 10 cm(3) K mol(-1) and fitting of the magnetisation data gives S=4, g=2.0 and D=-0.90 cm(-1). For complex 2, the value of chi(M)T falls to a value of approximately 5.0 cm(3) K mol(-1) at 1.8 K, which is consistent with a small spin ground state. For the triangular complex 3, the best fit to the experimental chi(M)T versus T data was obtained for the following parameters: Ja = -5.01 cm(-1), Jb = +9.16 cm(-1) and g=2.00, resulting in an S=2 spin ground state. DFT calculations on 3, however, suggest an S=1 or S=0 ground state with J(a)=-2.95 cm(-1) and J(b)=-2.12 cm(-1). AC susceptibility measurements performed on 1 in the 1.8-4.00 K range show the presence of out-of-phase AC susceptibility signals, but no peaks. Low-temperature single-crystal studies performed on 1 on an array of micro-SQUIDS show the time- and temperature-dependent hysteresis loops indicative of single-molecule magnetism behaviour.     

High nuclearity single-molecule magnets: a mixed-valence Mn26 cluster containing the di-2-pyridylketone diolate dianion

The employment of the dianion (dpkd(2-)) of the gem-diol form of di-2-pyridylketone (dpk) as a tetradentate chelate in manganese chemistry is reported, and the synthesis, crystal structure, and magnetochemical characterization of [Mn26O16(OMe)12(dpkd)12(MeOH)6](OH)6 x solv (3 x solv) are described. The reaction of Mn(ClO4)2 x 6 H2O, dpk, NaOMe, and NEt3 (2:1:4:2) in MeCN/MeOH affords complex 3, which possesses a rare metal topology and is mixed-valence (4 Mn(II), 22 Mn(III)). The complicated [Mn26(mu4-O)10(mu3-O)6(mu3-OMe)12(mu-OR)12](18+) core of 3 consists of an internal Mn(III)16 cage of adjacent Mn4 tetrahedra surrounded by an external Mn(II)4Mn(III)6 shell. The latter is held together by the alkoxide arms of twelve eta(1):eta(2):eta(1):eta(1):mu3 dpkd(2-) groups. Variable-temperature, solid-state direct current (dc), and alternating current (ac) magnetization studies were carried out on 3 in the 1.8-300 K range. Complex 3 is predominantly antiferromagnetically coupled with a resulting S = 6 ground state, a conclusion confirmed by the in-phase (chi'(M)) ac susceptibility data. The observation of out-of-phase (chi'(M)) ac susceptibility signals suggested that 3 might be a single-molecule magnet, and this was confirmed by single-crystal magnetization vs dc field sweeps that exhibited hysteresis, the diagnostic property of a magnet. Combined ac chi'(M) and magnetization decay vs time data collected below 1.1 K were used to construct an Arrhenius plot; the fit of the thermally activated region above approximately 0.1 K gave U(eff) = 30 K, where U(eff) is the effective relaxation barrier. At lower temperatures, the complex exhibits temperature-independent relaxation, characteristic of ground-state quantum tunneling of magnetization between the lowest-lying M(s) = +/-6 levels. The combined work demonstrates the ligating flexibility of dipyridyl-diolate chelates and their usefulness in the synthesis of polynuclear Mn(x) clusters with interesting magnetic properties, without requiring the co-presence of carboxylate ligands.     

New polynuclear manganese clusters from the use of the hydrophobic carboxylate ligand 2,2-dimethylbutyrate

The syntheses, structures, and magnetic properties are reported of [Mn12O12(O2CPe(t))16(MeOH)4] (4), [Mn6O2(O2CH2)(O2CPe(t))11(HO2CPe(t))2(O2CMe)] (5), [Mn9O6(OH)(CO3)(O2CPe(t))12(H2O)2] (6), and [Mn4O2(O2CPe(t))6(bpy)2] (7, bpy = 2,2'-bipyridine), where Pe(t) = tert-pentyl (Pe(t)CO2H = 2,2-dimethylbutyric acid). These complexes were all prepared from reactions of [Mn12O12(O2CPe(t))16(H2O)4] (3) in CH2Cl2. Complex 4 x 2MeCN crystallizes in the triclinic space group P1 and contains a central [Mn(IV)4O4] cubane core that is surrounded by a nonplanar ring of eight alternating Mn(III) and eight mu3-O(2-) ions. This is only the third Mn12 complex in which the four bound water molecules have been replaced by other ligands, in this case MeOH. Complex 5 x (1/2)CH2Cl2 crystallizes in the monoclinic space group P2(1)/c and contains two [Mn3(mu3-O)]7+ units linked at two of their apexes by two Pe(t)CO2(-) ligands and one mu4-CH2O2(2-) bridge. The complex is a new structural type in Mn chemistry, and also contains only the third example of a gem-diolate unit bridging four metal ions. Complex 6 x H2O x Pe(t)CO2H crystallizes in the orthorhombic space group Cmc2(1) and possesses a [Mn(III)9(mu3-O)6(mu-OH)(mu3-CO3)]12+ core. The molecule contains a mu3-CO3(2-) ion, the first example in a discrete Mn complex. Complex 7 x 2H2O crystallizes in the monoclinic space group P2(1)/c and contains a known [Mn(III)2Mn(II)2(mu3-O)2]6+ core that can be considered as two edge-sharing, triangular [Mn3O] units. Additionally, the synthesis and magnetic properties of a new enneanuclear cluster of formula [Mn9O7(O2CCH2Bu(t))13(THF)2] (8, THF = tetrahydrofuran) are reported. The molecule was obtained by the reaction of [Mn12O12(O2CCH2Bu(t))16(H2O)4] (2) with THF. Complexes 2 and 4 display quasireversible redox couples when examined by cyclic voltammetry in CH2Cl2; oxidations are observed at -0.07 V (2) and -0.21 V (4) vs ferrocene. The magnetic properties of complexes 4-8 have been studied by direct current (DC) and alternating current (AC) magnetic susceptibility techniques. The ground-state spin of 4 was established by magnetization measurements in the 1.80-4.00 K and 0.5-7 T ranges. Fitting of the reduced magnetization data by full matrix diagonalization, incorporating a full powder average and including only axial anisotropy, gave S = 10, g = 2.0(1), and D = -0.39(10) cm(-1). The complex exhibits two frequency-dependent out-of-phase AC susceptibility signals (chi(M)') indicative of slow magnetization relaxation. An Arrhenius plot obtained from chi(M)' vs T data gave an effective energy barrier to relaxation (U(eff)) of 62 and 35 K for the slower and faster relaxing species, respectively. These studies suggest that complex 4 is a single-molecule magnet (SMM). DC susceptibility studies on complexes 5-8 display overall antiferromagnetic behavior and indicate ground-state spin values of S < or = 2. AC susceptibility studies at < 10 K confirm these small values and indicate the population of low-lying excited states even at these low temperatures. This supports the small ground-state spin values to be due to spin frustration effects.     

Synthesis, structure, and magnetic properties of a Mn(21) single-molecule magnet

The reaction of [Mn(3)O(O(2)CMe)(6)(py)(3)](ClO(4)) (1; 3Mn(III)) with [Mn(10)O(4)(OH)(2)(O(2)CMe)(8)(hmp)(8)](ClO(4))(4) (2; 10Mn(III)) in MeCN affords the new mixed-valent complex [Mn(21)O(14)(OH)(2)(O(2)CMe)(16)(hmp)(8)(pic)(2)(py)(H(2)O)](ClO(4))(4) (3; 3Mn(II)-18Mn(III); hmp(-) is the anion of 2-(hydroxymethyl)pyridine), with an average Mn oxidation state of +2.85. Complex 3.7MeCN crystallizes in the triclinic space group P. The structure consists of a low symmetry [Mn(21)(micro(4)-O)(4)(micro(3)-O)(12)(micro-O)(16)] core, with peripheral ligation provided by 16 MeCO(2)(-), 8 hmp(-), and 2 pic(-) groups and one molecule each of water and pyridine. The magnetic properties of 3 were investigated by both dc and ac magnetic susceptibility measurements. Fitting of dc magnetization data collected in the 0.1-0.8 T and 1.8-4.0 K ranges gave S = (17)/(2), D approximately -0.086 cm(-)(1), and g approximately 1.8, where S is the molecular spin of the Mn(21) complex and D is the axial zero-field splitting parameter. ac susceptibility studies in the 10-997 Hz frequency range reveal the presence of a frequency-dependent out-of-phase ac magnetic susceptibility (chi(M)' ') signal consistent with slow magnetization relaxation rates. Fitting of dc magnetization decay versus time data to the Arrhenius equation gave a value of the effective barrier to relaxation (U(eff)) of 13.2 K. Magnetization versus applied dc field sweeps exhibited hysteresis. Thus, complex 3 is a new member of the small but growing family of single-molecule magnets.     

Tetranuclear and Octanuclear Manganese Carboxylate Clusters: Preparation and Reactivity of (NBu(n)(4))[Mn(4)O(2)(O(2)CPh)(9)(H(2)O)] and Synthesis of (NBu(n)(4))(2)[Mn(8)O(4)(O(2)CPh)(12)(Et(2)mal)(2)(H(2)O)(2)] with a "Linked-Butterfly" Structure

The reaction of Mn(O(2)CPh)(2).2H(2)O and PhCO(2)H in EtOH/MeCN with NBu(n)(4)MnO(4) gives (NBu(n)(4))[Mn(4)O(2)(O(2)CPh)(9)(H(2)O)] (4) in high yield (85-95%). Complex 4 crystallizes in monoclinic space group P2(1)/c with the following unit cell parameters at -129 degrees C: a = 17.394(3) ?, b = 19.040(3) ?, c = 25.660(5) ?, beta = 103.51(1) degrees, V = 8262.7 ?(3), Z = 4; the structure was refined on F to R (R(w)) = 9.11% (9.26%) using 4590 unique reflections with F > 2.33sigma(F). The anion of 4 consists of a [Mn(4)(&mgr;(3)-O)(2)](8+) core with a "butterfly" disposition of four Mn(III) atoms. In addition to seven bridging PhCO(2)(-) groups, there is a chelating PhCO(2)(-) group at one "wingtip" Mn atom and terminal PhCO(2)(-) and H(2)O groups at the other. Complex 4 is an excellent steppingstone to other [Mn(4)O(2)]-containing species. Treatment of 4 with 2,2-diethylmalonate (2 equiv) leads to isolation of (NBu(n)(4))(2)[Mn(8)O(4)(O(2)CPh)(12)(Et(2)mal)(2)(H(2)O)(2)] (5) in 45% yield after recrystallization. Complex 5 is mixed-valent (2Mn(II),6Mn(III)) and contains an [Mn(8)O(4)](14+) core that consists of two [Mn(4)O(2)](7+) (Mn(II),3Mn(III)) butterfly units linked together by one of the &mgr;(3)-O(2)(-) ions in each unit bridging to one of the body Mn atoms in the other unit, and thus converting to &mgr;(4)-O(2)(-) modes. The Mn(II) ions are in wingtip positions. The Et(2)mal(2)(-) groups each bridge two wingtip Mn atoms from different butterfly units, providing additional linkage between the halves of the molecule. Complex 5.4CH(2)Cl(2) crystallizes in monoclinic space group P2(1)/c with the following unit cell parameters at -165 degrees C: a = 16.247(5) ?, b = 27.190(8) ?, c = 17.715(5) ?, beta = 113.95(1) degrees, V = 7152.0 ?(3), Z = 4; the structure was refined on F to R (R(w)) = 8.36 (8.61%) using 4133 unique reflections with F > 3sigma(F). The reaction of 4 with 2 equiv of bpy or picolinic acid (picH) yields the known complex Mn(4)O(2)(O(2)CPh)(7)(bpy)(2) (2), containing Mn(II),3Mn(III), or (NBu(n)(4))[Mn(4)O(2)(O(2)CPh)(7)(pic)(2)] (6), containing 4Mn(III). Treatment of 4 with dibenzoylmethane (dbmH, 2 equiv) gives the mono-chelate product (NBu(n)(4))[Mn(4)O(2)(O(2)CPh)(8)(dbm)] (7); ligation of a second chelate group requires treatment of 7 with Na(dbm), which yields (NBu(n)(4))[Mn(4)O(2)(O(2)CPh)(7)(dbm)(2)] (8). Complexes 7 and 8 both contain a [Mn(4)O(2)](8+) (4Mn(III)) butterfly unit. Complex 7 contains chelating dbm(-) and chelating PhCO(2)(-) at the two wingtip positions, whereas 8 contains two chelating dbm(-) groups at these positions, as in 2 and 6. Complex 7.2CH(2)Cl(2) crystallizes in monoclinic space group P2(1) with the following unit cell parameters at -170 degrees C: a = 18.169(3) ?, b = 19.678(4) ?, c = 25.036(4) ?, beta = 101.49(1) degrees, V = 8771.7 ?(3), Z = 4; the structure was refined on F to R (R(w)) = 7.36% (7.59%) using 10 782 unique reflections with F > 3sigma(F). Variable-temperature magnetic susceptibility studies have been carried out on powdered samples of complexes 2 and 5 in a 10.0 kG field in the 5.0-320.0 K range. The effective magnetic moment (&mgr;(eff)) for 2 gradually decreases from 8.61 &mgr;(B) per molecule at 320.0 K to 5.71 &mgr;(B) at 13.0 K and then increases slightly to 5.91 &mgr;(B) at 5.0 K. For 5, &mgr;(eff) gradually decreases from 10.54 &mgr;(B) per molecule at 320.0 K to 8.42 &mgr;(B) at 40.0 K, followed by a more rapid decrease to 6.02 &mgr;(B) at 5.0 K. On the basis of the crystal structure of 5 showing the single Mn(II) ion in each [Mn(4)O(2)](7+) subcore to be at a wingtip position, the Mn(II) ion in 2 was concluded to be at a wingtip position also. Employing the reasonable approximation that J(w)(b)(Mn(II)/Mn(III)) = J(w)(b)(Mn(III)/M(III)), where J(w)(b) is the magnetic exchange interaction between wingtip (w) and body (b) Mn ions of the indicated oxidation state, a theoretical chi(M) vs T expression was derived and used to fit the experimental molar magnetic susceptibility (chi(M)) vs T data. The obtained fitting parameters were J(w)(b) = -3.9 cm(-)(1), J(b)(b) = -9.2 cm(-)(1), and g = 1.80. These values suggest a S(T) = (5)/(2) ground state spin for 2, which was confirmed by magnetization vs field measurements in the 0.5-50.0 kG magnetic field range and 2.0-30.0 K temperature range. For complex 5, since the two bonds connecting the two [Mn(4)O(2)](7+) units are Jahn-Teller elongated and weak, it was assumed that complex 5 could be treated, to a first approximation, as consisting of weakly-interacting halves; the magnetic susceptibility data for 5 at temperatures >/=40 K were therefore fit to the same theoretical expression as used for 2, and the fitting parameters were J(w)(b) = -14.0 cm(-)(1) and J(b)(b) = -30.5 cm(-)(1), with g = 1.93 (held constant). These values suggest an S(T) = (5)/(2) ground state spin for each [Mn(4)O(2)](7+) unit of 5, as found for 2. The interactions between the subunits are difficult to incorporate into this model, and the true ground state spin value of the entire Mn(8) anion was therefore determined by magnetization vs field studies, which showed the ground state of 5 to be S(T) = 3. The results of the studies on 2 and 5 are considered with respect to spin frustration effects within the [Mn(4)O(2)](7+) units. Complexes 2 and 5 are EPR-active and -silent, respectively, consistent with their S(T) = (5)/(2) and S(T) = 3 ground states, respectively.     

Heptanuclear and decanuclear manganese complexes with the anion of 2-hydroxymethylpyridine

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.     

Novel rectangular [Fe4(mu4-OHO)(mu-OH)(2)](7+) versus "butterfly" [Fe4(mu3-O2](8+) core topology in the Fe(III)/RCO2(-)/phen reaction systems (R = Me,Ph; phen = 1,10-phenanthroline): preparation and properties of [Fe4(OHO)(OH)(2)(O2CMe)(4)(phen)(4)](ClO4)(3), [Fe4O2(O2CPh)(7)(phen)(2)](ClO4), and [Fe4O2(O2CPh)(8)(phen)(2)

The preparations, X-ray structures, and detailed physical characterizations are presented for three new tetranuclear Fe(III)/RCO(2)(-)/phen complexes, where phen = 1,10-phenanthroline: [Fe(4)(OHO)(OH)(2)(O(2)CMe)(4)(phen)(4)](ClO(4))(3).4.4MeCN.H(2)O (1.4.4MeCN.H(2)O); [Fe(4)O(2)(O(2)CPh)(7)(phen)(2)](ClO(4)).2MeCN (2.2MeCN); [Fe(4)O(2)(O(2)CPh)(8)(phen)(2)].2H(2)O (3.2H(2)O). Complex 1.4.4MeCN.H(2)O crystallizes in space group P2(1)/n, with a = 18.162(9) A, b = 39.016(19) A, c = 13.054(7) A, beta = 104.29(2) degrees, Z = 4, and V = 8963.7 A(3). Complex 2.2MeCN crystallizes in space group P2(1)/n, with a = 18.532(2) A, b = 35.908(3) A, c = 11.591(1) A, beta = 96.42(1) degrees, Z = 4, and V = 7665(1) A(3). Complex 3.2H(2)O crystallizes in space group I2/a, with a = 18.79(1) A, b = 22.80(1) A, c = 20.74(1) A, beta = 113.21(2) degrees, Z = 4, and V = 8166(1) A(3). The cation of 1 contains the novel [Fe(4)(mu(4)-OHO)(mu-OH)(2)](7+) core. The core structure of 2 and 3 consists of a tetranuclear bis(mu(3)-O) cluster disposed in a "butterfly" arrangement. Magnetic susceptibility data were collected on 1-3 in the 2-300 K range. For the rectangular complex 1, fitting the data to the appropriate theoretical chi(M) vs T expression gave J(1) = -75.4 cm(-1), J(2) = -21.4 cm(-1), and g = 2.0(1), where J(1) and J(2) refer to the Fe(III)O(O(2)CMe)(2)Fe(III) and Fe(III)(OH)Fe(III) pairwise exchange interactions, respectively. The S = 0 ground state of 1 was confirmed by 2 K magnetization data. The data for 2 and 3 reveal a diamagnetic ground state with antiferromagnetic exchange interactions among the four high-spin Fe(III) ions. The exchange coupling constant J(bb) ("body-body" interaction) is indeterminate due to prevailing spin frustration, but the "wing-body" antiferromagnetic interaction (J(wb)) was evaluated to be -77.6 and -65.7 cm(-1) for 2 and 3, respectively, using the appropriate spin Hamiltonian approach. M?ssbauer spectra of 1-3 are consistent with high-spin Fe(III) ions. The data indicated asymmetry of the Fe(4) core of 1 at 80 K, which is not detected at room temperature due to thermal motion of the core. The spectra of 2 and 3 analyze as two quadrupole-split doublets which were assigned to the body and wing-tip pairs of metal ions. (1)H NMR spectra are reported for 1-3 with assignment of the main resonances.     

Mn8 and Mn16 clusters from the use of 2-(hydroxymethyl)pyridine, and comparison with the products from bulkier chelates: a new high nuclearity single-molecule magnet

The synthesis, crystal structures, and magnetochemical characterization of two new Mn clusters [Mn(8)O(2)(O(2)CPh)(10)(hmp)(4)(MeOH)(2)] (1; 6Mn(II), 2Mn(III)) and [Mn(16)O(8)(OH)(2)(O(2)CPh)(12)(hmp)(10)(H(2)O)(2)](O(2)CPh)(2) (2; 6Mn(II), 10Mn(III)) are reported. They were obtained from the use of 2-(hydroxymethyl)pyridine (hmpH) under the same reaction conditions but differing in the presence or absence of added base. Thus, the reaction of hmpH with Mn(O(2)CPh)(2) in CH(2)Cl(2)/MeOH led to isolation of octanuclear complex 1, whereas the analogous reaction in the presence of NEt(3) gave hexadecanuclear complex 2. Complexes 1 and 2 possess either very rare or unprecedented core structures that are related to each other: that of 1 can be described as a linked pair of incomplete [Mn(4)O(3)] cubanes, while that of 2 consists of a linked pair of complete [Mn(4)O(4)] cubanes, on either side of which is attached a tetrahedral [Mn(4)(μ(4)-O)] unit. Solid-state direct current (dc) and alternating current (ac) magnetic susceptibility measurements on 1 and 2 establish that they possess S = 5 and 8 ground states, respectively. Complex 2 exhibits frequency-dependent out-of-phase (χ(M)") ac susceptibility signals at temperatures below 3 K suggestive of a single-molecule magnet (SMM). Magnetization versus applied dc field sweeps on single crystals of 2·10MeOH down to 0.04 K exhibited hysteresis, confirming 2 to be a new SMM. Comparison of the structure of 2 (Mn(16)) with Mn(12) or Mn(6) clusters previously obtained under the same reaction conditions but with two Me or two Ph groups, respectively, added next to the alkoxide O atom of hmp(-) indicate their influence on the nuclearity and structure of the products as being due to the overall bulk of the chelate plus the decreased ability of the O atom to bridge.     

Single-molecule magnets: novel Mn(8) and Mn(9) carboxylate clusters containing an unusual pentadentate ligand derived from pyridine-2,6-dimethanol

The reactions of the Mn(III)(3) and Mn(II)Mn(III)(2) complexes [Mn(3)O(O(2)CEt)(6)(py)(3)][ClO(4)] and [Mn(3)O(O(2)CEt)(6)(py)(3)] with pyridine-2,6-dimethanol (pdmH(2)) afford the mixed-valence Mn(II)(6)Mn(III)(2) octanuclear complex [Mn(8)O(2)(py)(4)(O(2)CEt)(8)(L)(2)][ClO(4)](2) (1) and the Mn(II)(7)Mn(III)(2) enneanuclear complex [Mn(9)(O(2)CEt)(12)(pdm)(pdmH)(2)(L)(2)] (2), respectively. Both compounds contain a novel pentadentate ligand, the dianion of (6-hydroxymethylpyridin-2-yl)-(6-hydroxymethylpyridin-2-ylmethoxy)methanol (LH(2)), which is the hemiacetal formed in situ from the Mn-assisted oxidation of pdmH(2). Complex 1 crystallizes in the monoclinic space group P2(1)/n with the following cell parameters at -160 degrees C: a = 16.6942(5) A, b = 13.8473(4) A, c = 20.0766(6) A, beta = 99.880(1) degrees, V = 4572.27 A(3), and Z = 2, R (R(w)) = 4.78 (5.25). Complex 2.0.2MeCN crystallizes in the triclinic space group Ponemacr; with the following cell parameters at -157 degrees C: a = 12.1312(4) A, b = 18.8481(6) A, c = 23.2600(7) A, alpha = 78.6887(8) degrees, beta = 77.9596(8) degrees, gamma = 82.3176(8) degrees, V = 5076.45 A(3), and Z = 2, R (R(w)) = 4.12 (4.03). Both complexes are new structural types comprising distorted-cubane units linked together, albeit in two very different ways. In addition, complex 2 features three distinct binding modes for the chelating ligands derived from deprotonated pdmH(2). Complexes 1 and 2 were characterized by variable-temperature ac and dc magnetic susceptibility measurements and found to possess spin ground states of 0 and 11/2, respectively. Least-squares fitting of the reduced magnetization data gave S = 11/2, g = 2.0, and D = -0.11 cm(-1) for complex 2, where D is the axial zero-field splitting parameter. Direct current magnetization versus field studies on 2 at <1 K show hysteresis behavior at <0.3 K, establishing 2 as a new single-molecule magnet. Magnetization decay measurements gave an effective barrier to magnetization relaxation of U(eff) = 3.1 cm(-1) = 4.5 K.     

Synthetic entry into polynuclear bismuth-manganese chemistry: high oxidation state Bi(III)2Mn(IV)6 and Bi(III)Mn(III)10 complexes

The first high nuclearity, mixed-metal Bi(III)/Mn(IV) and Bi(III)/Mn(III) complexes are reported. The former complexes are [Bi(2)Mn(IV)(6)O(9)(O(2)CEt)(9)(HO(2)CEt)(NO(3))(3)] (1) and [Bi(2)Mn(IV)(6)O(9)(O(2)CPh)(9)(HO(2)CPh)(NO(3))(3)] (2) and were obtained from the comproportionation reaction between Mn(O(2)CR)(2) and MnO(4)(-) in a 10:3 ratio in the presence of Bi(NO(3))(3) (3 equiv) in either a H(2)O/EtCO(2)H (1) or MeCN/PhCO(2)H (2) solvent medium. The same reaction that gives 2, but with Bi(O(2)CMe)(3) and MeNO(2) in place of Bi(NO(3))(3) and MeCN, gave the lower oxidation state product [BiMn(III)(10)O(8)(O(2)CPh)(17)(HO(2)CPh)(H(2)O)] (3). Complexes 1 and 2 are near-isostructural and possess an unusual and high symmetry core topology consisting of a Mn(IV)(6) wheel with two central Bi(III) atoms capping the wheel on each side. In contrast, the [BiMn(III)(10)O(8)](17+) core of 3 is low symmetry, comprising a [BiMn(3)(μ(3)-O)(2)](8+) butterfly unit, four [BiMn(3)(μ(4)-O)](10+) tetrahedra, and two [BiMn(2)(μ(3)-O)](7+) triangles all fused together by sharing common Mn and Bi vertices. Variable-temperature, solid-state dc and ac magnetization data on 1-3 in the 1.8-300 K range revealed that 1 and 2 possess an S = 0 ground state spin, whereas 3 possesses an S = 2 ground state. The work offers the possibility of access to molecular analogs of the multifunctional Bi/Mn/O solids that are of such great interest in materials science.