Enneanuclear [Ni₆Ln₃] Cages: [Ln^III₃] Triangles Capping [Ni^II₆] Trigonal Prisms Including a [Ni₆Dy₃] Single-Molecule Magnet

The use of (2-(β-naphthalideneamino)-2-hydroxymethyl-1-propanol) ligand, H₃L, in Ni/Ln chemistry has led to the isolation of three new isostructural [Ni^II₆Ln^III₃] metallic cages. More specifically, the reaction of Ni­(ClO₄)₂·6H₂O, the corresponding lanthanide nitrate salt, and H₃L in MeCN, under solvothermal conditions in the presence of NEt₃, led to the isolation of three complexes with the formulas [Ni₆Gd₃(OH)₆(HL)₆(NO₃)₃]·5.75MeCN·2Et₂O·1.5H₂O (<b>1</b>·5.75MeCN·2Et₂O·1.5H₂O), [Ni₆Dy₃(OH)₆(HL)₆(NO₃)₃]·2MeCN·2.7Et₂O·2.4H₂O (<b>2</b>·2MeCN·2.7Et₂O·2.4H₂O), and [Ni₆Er₃(OH)₆(HL)₆(NO₃)₃]·5.75MeCN·2Et₂O·1.5H₂O (<b>3</b>·5.75MeCN·2Et₂O·1.5H₂O). The structure of all three clusters describes a [Ln^III₃] triangle capping a [Ni^II₆] trigonal prism. Direct current magnetic susceptibility studies in the 5–300 K range for complexes <b>1</b>–<b>3</b> reveal the different nature of the magnetic interactions within the clusters: dominant antiferromagnetic exchange interactions for the Dy^III and Er^III analogues and dominant ferromagnetic interactions for the Gd^III example. Alternating current magnetic susceptibility measurements under zero external dc field displayed fully formed temperature- and frequency-dependent out-of-phase peaks for the [Ni^II₆Dy^III₃] analogue, establishing its single molecule magnetism behavior with <i>U</i>_eff = 24 K

New members of the [Mn₆/oxime] family and analogues with converging [Mn₃] planes

<p>The synthesis, structural, and magnetic characterization of five new members of the hexanuclear oximate [Mn^III₆] family are reported. All five clusters can be described with the general formula [Mn^III₆O₂(R-sao)₆(R′-CO₂)₂(sol)_x(H₂O)_y] (where R-saoH₂ = salicylaldoxime substituted at the oxime carbon with R = H, Me and Et; R′ = 1-naphthalene, 2-naphthalene, and 1-pyrene; sol = MeOH, EtOH, or MeCN; <i>x</i> = 0–4 and <i>y</i> = 0–4). More specifically, the reaction of Mn(ClO₄)₂·6H₂O with salicylaldoxime-like ligands and the appropriate carboxylic acid in alcoholic or MeCN solutions in the presence of base afforded complexes <b>1</b>–<b>5</b>: [Mn₆O₂(Me-sao)₆(1-naphth-CO₂)₂(H₂O)(MeCN)]·4MeCN (<b>1</b>·4MeCN); [Mn₆O₂(Me-sao)₆(2-naphth-CO₂)₂(H₂O)(MeCN)]·3MeCN·0.1H₂O (<b>2</b>·3MeCN·0.1H₂O); [Mn₆O₂(Et-sao)₆(2-naphth-CO₂)₂(EtOH)₄(H₂O)₂] (<b>3</b>); [Mn₆O₂(Et-sao)₆(2-naphth-CO₂)₂(MeOH)₆] (<b>4</b>) and [Mn₆O₂(sao)₆(1-pyrene-CO₂)₂(H₂O)₂(EtOH)₂]·6EtOH (<b>5</b>·6EtOH). Clusters <b>3</b>, <b>4,</b> and <b>5</b> display the usual [Mn₆/oximate] structural motif consisting of two [Mn₃O] subunits bridged by two O_oximate atoms from two R-sao²⁻ ligands to form the hexanuclear complex in which the two triangular [Mn₃] units are parallel to each other. On the contrary, clusters <b>1</b> and <b>2</b> display a highly distorted stacking arrangement of the two [Mn₃] subunits resulting in two converging planes, forming a novel motif in the [Mn₆] family. Investigation of the magnetic properties for all complexes reveal dominant antiferromagnetic interactions for <b>1</b>, <b>2,</b> and <b>5</b>, while <b>3</b> and <b>4</b> display dominant ferromagnetic interactions with a ground state of <i>S</i> = 12 for both clusters. Finally, <b>3</b> and <b>4</b> display single-molecule magnet behavior with <i>U</i>_eff = 63 and 36 K, respectively.</p

2-Aminoisobutyric Acid in Co(II) and Co(II)/Ln(III) Chemistry: Homometallic and Heterometallic Clusters

The synthesis and magnetic properties of 13 new homo- and heterometallic Co­(II) complexes containing the artificial amino acid 2-amino-isobutyric acid, aibH, are reported: [Co^II₄(aib)₃(aibH)₃(NO₃)]­(NO₃)₄·2.8CH₃OH·0.2H₂O (<b>1</b>·2.8CH₃OH·0.2H₂O), {Na₂[Co^II₂(aib)₂(N₃)₄(CH₃OH)₄]}_<i>n</i> (<b>2</b>), [Co^II₆La^III(aib)₆(OH)₃(NO₃)₂(H₂O)₄(CH₃CN)₂]·0.5­[La­(NO₃)₆]·0.75­(ClO₄)·1.75­(NO₃)·3.2CH₃CN·5.9H₂O (<b>3</b>·3.2CH₃CN·5.9H₂O), [Co^II₆Pr^III(aib)₆(OH)₃(NO₃)₃(CH₃CN)₆]·[Pr­(NO₃)₅]·0.41­[Pr­(NO₃)₃(ClO₄)_0.5(H₂O)_1.5]·0.59­[Co­(NO₃)₃(H₂O)]·0.2­(ClO₄)·0.25H₂O (<b>4</b>·0.25H₂O), [Co^II₆Nd^III(aib)₆(OH)₃(NO₃)_2.8(CH₃OH)_4.7(H₂O)_1.5]·2.7­(ClO₄)·0.5­(NO₃)·2.26CH₃OH·0.24H₂O (<b>5</b>·2.26CH₃OH·0.24H₂O), [Co^II₆Sm^III(aib)₆(OH)₃(NO₃)₃(CH₃CN)₆]·[Sm­(NO₃)₅]·0.44­[Sm­(NO₃)₃(ClO₄)_0.5(H₂O)_1.5]·0.56­[Co­(NO₃)₃(H₂O)]·0.22­(ClO₄)·0.3H₂O (<b>6</b>·0.3H₂O), [Co^II₆Eu^III(aib)₆(OH)₃(NO₃)₃(CH₃OH)_4.87(H₂O)_1.13]­(ClO₄)_2.5(NO₃)_0.5·2.43CH₃OH·0.92H₂O (<b>7</b>·2.43CH₃OH·0.92H₂O), [Co^II₆Gd^III(aib)₆(OH)₃(NO₃)_2.9(CH₃OH)_4.9(H₂O)_1.2]·2.6­(ClO₄)·0.5­(NO₃)·2.58CH₃OH·0.47H₂O (<b>8</b>·2.58CH₃OH·0.47H₂O), [Co^II₆Tb^III(aib)₆(OH)₃(NO₃)₃(CH₃CN)₆]·[Tb­(NO₃)₅]·0.034­[Tb­(NO₃)₃(ClO₄)_0.5(H₂O)_0.5]·0.656­[Co­(NO₃)₃(H₂O)]·0.343­(ClO₄)·0.3H₂O (<b>9</b>·0.3H₂O), [Co^II₆Dy^III(aib)₆(OH)₃(NO₃)_2.9(CH₃OH)_4.92(H₂O)_1.18]­(ClO₄)_2.6(NO₃)_0.5·2.5CH₃OH·0.5H₂O (<b>10</b>·2.5CH₃OH·0.5H₂O), [Co^II₆Ho^III(aib)₆(OH)₃(NO₃)₃(CH₃CN)₆]·0.27­[Ho­(NO₃)₃(ClO₄)_0.35(H₂O)_0.15]·0.656­[Co­(NO₃)₃(H₂O)]·0.171­(ClO₄) (<b>11</b>), [Co^II₆Er^III(aib)₆(OH)₄(NO₃)₂(CH₃CN)_2.5(H₂O)_3.5]­(ClO₄)₃·CH₃CN·0.75H₂O (<b>12</b>·CH₃CN·0.75H₂O), and [Co^II₆Tm^III(aib)₆(OH)₃(NO₃)₃(H₂O)₆]·1.48­(ClO₄)·1.52­(NO₃)·3H₂O (<b>13</b>·3H₂O). Complex <b>1</b> describes a distorted tetrahedral metallic cluster, while complex <b>2</b> can be considered to be a 2-D coordination polymer. Complexes <b>3</b>–<b>13</b> can all be regarded as metallo-cryptand encapsulated lanthanides in which the central lanthanide ion is captivated within a [Co^II₆] trigonal prism. dc and ac magnetic susceptibility studies have been carried out in the 2–300 K range for complexes <b>1</b>, <b>3</b>, <b>5</b>, <b>7</b>, <b>8</b>, <b>10</b>,<b> 12</b>, and <b>13</b>, revealing the possibility of single molecule magnetism behavior for complex <b>10</b>

2-Aminoisobutyric Acid in Co(II) and Co(II)/Ln(III) Chemistry: Homometallic and Heterometallic Clusters

The synthesis and magnetic properties of 13 new homo- and heterometallic Co­(II) complexes containing the artificial amino acid 2-amino-isobutyric acid, aibH, are reported: [Co^II₄(aib)₃(aibH)₃(NO₃)]­(NO₃)₄·2.8CH₃OH·0.2H₂O (<b>1</b>·2.8CH₃OH·0.2H₂O), {Na₂[Co^II₂(aib)₂(N₃)₄(CH₃OH)₄]}_<i>n</i> (<b>2</b>), [Co^II₆La^III(aib)₆(OH)₃(NO₃)₂(H₂O)₄(CH₃CN)₂]·0.5­[La­(NO₃)₆]·0.75­(ClO₄)·1.75­(NO₃)·3.2CH₃CN·5.9H₂O (<b>3</b>·3.2CH₃CN·5.9H₂O), [Co^II₆Pr^III(aib)₆(OH)₃(NO₃)₃(CH₃CN)₆]·[Pr­(NO₃)₅]·0.41­[Pr­(NO₃)₃(ClO₄)_0.5(H₂O)_1.5]·0.59­[Co­(NO₃)₃(H₂O)]·0.2­(ClO₄)·0.25H₂O (<b>4</b>·0.25H₂O), [Co^II₆Nd^III(aib)₆(OH)₃(NO₃)_2.8(CH₃OH)_4.7(H₂O)_1.5]·2.7­(ClO₄)·0.5­(NO₃)·2.26CH₃OH·0.24H₂O (<b>5</b>·2.26CH₃OH·0.24H₂O), [Co^II₆Sm^III(aib)₆(OH)₃(NO₃)₃(CH₃CN)₆]·[Sm­(NO₃)₅]·0.44­[Sm­(NO₃)₃(ClO₄)_0.5(H₂O)_1.5]·0.56­[Co­(NO₃)₃(H₂O)]·0.22­(ClO₄)·0.3H₂O (<b>6</b>·0.3H₂O), [Co^II₆Eu^III(aib)₆(OH)₃(NO₃)₃(CH₃OH)_4.87(H₂O)_1.13]­(ClO₄)_2.5(NO₃)_0.5·2.43CH₃OH·0.92H₂O (<b>7</b>·2.43CH₃OH·0.92H₂O), [Co^II₆Gd^III(aib)₆(OH)₃(NO₃)_2.9(CH₃OH)_4.9(H₂O)_1.2]·2.6­(ClO₄)·0.5­(NO₃)·2.58CH₃OH·0.47H₂O (<b>8</b>·2.58CH₃OH·0.47H₂O), [Co^II₆Tb^III(aib)₆(OH)₃(NO₃)₃(CH₃CN)₆]·[Tb­(NO₃)₅]·0.034­[Tb­(NO₃)₃(ClO₄)_0.5(H₂O)_0.5]·0.656­[Co­(NO₃)₃(H₂O)]·0.343­(ClO₄)·0.3H₂O (<b>9</b>·0.3H₂O), [Co^II₆Dy^III(aib)₆(OH)₃(NO₃)_2.9(CH₃OH)_4.92(H₂O)_1.18]­(ClO₄)_2.6(NO₃)_0.5·2.5CH₃OH·0.5H₂O (<b>10</b>·2.5CH₃OH·0.5H₂O), [Co^II₆Ho^III(aib)₆(OH)₃(NO₃)₃(CH₃CN)₆]·0.27­[Ho­(NO₃)₃(ClO₄)_0.35(H₂O)_0.15]·0.656­[Co­(NO₃)₃(H₂O)]·0.171­(ClO₄) (<b>11</b>), [Co^II₆Er^III(aib)₆(OH)₄(NO₃)₂(CH₃CN)_2.5(H₂O)_3.5]­(ClO₄)₃·CH₃CN·0.75H₂O (<b>12</b>·CH₃CN·0.75H₂O), and [Co^II₆Tm^III(aib)₆(OH)₃(NO₃)₃(H₂O)₆]·1.48­(ClO₄)·1.52­(NO₃)·3H₂O (<b>13</b>·3H₂O). Complex <b>1</b> describes a distorted tetrahedral metallic cluster, while complex <b>2</b> can be considered to be a 2-D coordination polymer. Complexes <b>3</b>–<b>13</b> can all be regarded as metallo-cryptand encapsulated lanthanides in which the central lanthanide ion is captivated within a [Co^II₆] trigonal prism. dc and ac magnetic susceptibility studies have been carried out in the 2–300 K range for complexes <b>1</b>, <b>3</b>, <b>5</b>, <b>7</b>, <b>8</b>, <b>10</b>,<b> 12</b>, and <b>13</b>, revealing the possibility of single molecule magnetism behavior for complex <b>10</b>

Heptanuclear Heterometallic [Cu₆Ln] Clusters: Trapping Lanthanides into Copper Cages with Artificial Amino Acids

Employment of the artificial amino acid 2-amino-isobutyric acid, aibH, in Cu^II and Cu^II/Ln^III chemistry led to the isolation and characterization of 12 new heterometallic heptanuclear [Cu₆Ln­(aib)₆(OH)₃(OAc)₃(NO₃)₃] complexes consisting of trivalent lanthanide centers within a hexanuclear copper trigonal prism (aibH = 2-amino-butyric acid; Ln = Ce (<b>1</b>), Pr (<b>2</b>), Nd (<b>3</b>), Sm (<b>4</b>), Eu (<b>5</b>), Gd (<b>6</b>), Tb (<b>7</b>), Dy (<b>8</b>), Ho (<b>9</b>), Er (<b>10</b>), Tm (<b>11</b>), and Yb (<b>12</b>)). Direct curent magnetic susceptibility studies have been carried out in the 5–300 K range for all complexes, revealing the different nature of the magnetic interactions between the 3d–4f metallic pairs: dominant antiferromagnetic interactions for the majority of the pairs and dominant ferromagnetic interactions for when the lanthanide center is Gd^III and Dy^III. Furthermore, alternating current magnetic susceptibility studies reveal the possibility of single-molecule magnetism behavior for complexes <b>7</b> and <b>8</b>. Finally, complexes <b>2</b>, <b>5</b>–<b>8</b>, <b>10</b>, and <b>12</b> were analyzed using positive ion electrospray mass spectrometry (ES-MS), establishing the structural integrity of the heterometallic heptanuclear cage structure in acetonitrile