A Doughnut-Like (Mn^III)₁₂ Metallocycle Formed by a Rigid Angular Bis-Catecholate with a Nanometer-Sized Central Hole

Reaction of the rigid angular ligand tetrahydroxy-9,10-dimethyl-9,10-dihydro-9,10-ethanoanthracene, hereafter LH4, with Mn(CH3CO2)2·2H2O in a basic aqueous medium, in air, affords a crystalline product of composition Na12{[Mn(H2O)]12L12}·xH2O. Single-crystal X-ray diffraction reveals the presence of large [MnIII12L12]12− metallocycles of roughly hexagonal appearance, somewhat resembling a doughnut in which the central hole (van der Waals surface to surface) is roughly a nanometer across. This is the first example of a metal derivative of the fully deprotonated form, L4−. Associations with aquated Na+ counterions lead to a pleasingly symmetrical packing arrangement resembling honeycomb, with the central holes of individual metallocycles lined up one above the other. The ligand L4−, on account of its rigid angularity and its strong metal binding properties, promises to provide a rich source of unusual metal-containing structures, in particular cages, in future studies

Guanidinium Ion as a Symmetrical Template in the Formation of Cubic Hydrogen-Bonded Borate Networks with the Boracite Topology

Reaction between boric acid and guanidinium salts in methanolic solution at room temperature in the presence of various bases and anions gives well-formed solvated crystals of composition {[B(OCH3)4]3[C(NH2)3]4}+X-. The products in which X- = Cl- and PF6- are characterized by single-crystal X-ray diffraction. The tetramethoxyborate and guanidinium components form a highly symmetrical (cubic) hydrogen-bonded 3D network having the “boracite topology” [i.e., the (63)(6284) topology]. Highly disordered solvent molecules and anions occupy methyl-surfaced cavities and channels that represent more than 30% of the space

A New Approach to TCNQ-Based Coordination Polymers via TCNQH₂

2,2′-(p-Phenylene)bis(propanedinitrile), (NC)2CH·C6H4·CH(CN)2 (referred to as TCNQH2), upon reaction with Cd(NO3)2, [(C6H5)3PMe]Br, and Li(CH3CO2) in MeOH/DMF at room temperature in air yields an air-stable product of composition (Ph3PMe)2[Cd2(TCNQ)3] in the form of rhombohedral single crystals amenable to X-ray diffraction studies. In the anionic three-dimensional (3D) {[Cd2(TCNQ)3]2−}∞ coordination network Cd centers are in an approximately octahedral coordination environment consisting of N atoms from six TCNQ2− units each of which is in turn attached to four Cd2+ centers at the corners of a quadrilateral that is almost a square. The disposition of the Cd centers is only very slightly distorted from primitive cubic. The results constitute a “proof of concept” for our proposition that easily accessible, air-stable TCNQH2 may afford a very convenient general entry into new types of coordination polymers based on the TCNQ2− anion and that these in turn may be amenable to redox intercalation to afford materials in which TCNQ is present either as the TCNQ− radical or in mixed oxidation states

Highly Efficient Separation of a Solid Mixture of Naphthalene and Anthracene by a Reusable Porous Metal–Organic Framework through a Single-Crystal-to-Single-Crystal Transformation

The three-dimensional crystalline porous metal–organic framework [Ni2(μ2-OH2)(1,3-BDC)2(tpcb)]n (1) [1,3-H2BDC = 1,3-benzenedicarboxylic acid; tpcb = tetrakis(4-pyridyl)cyclobutane] was used to separate a solid mixture of naphthalene and anthracene at room temperature via selective adsorption of naphthalene. The process involved a single-crystal-to-single-crystal transformation. The guest naphthalene molecules could be exchanged with ethanol, and the host, 1, could be regenerated by removal of the guest ethanol molecules

A Doughnut-Like (Mn^III)₁₂ Metallocycle Formed by a Rigid Angular Bis-Catecholate with a Nanometer-Sized Central Hole

Reaction of the rigid angular ligand tetrahydroxy-9,10-dimethyl-9,10-dihydro-9,10-ethanoanthracene, hereafter LH4, with Mn(CH3CO2)2·2H2O in a basic aqueous medium, in air, affords a crystalline product of composition Na12{[Mn(H2O)]12L12}·xH2O. Single-crystal X-ray diffraction reveals the presence of large [MnIII12L12]12− metallocycles of roughly hexagonal appearance, somewhat resembling a doughnut in which the central hole (van der Waals surface to surface) is roughly a nanometer across. This is the first example of a metal derivative of the fully deprotonated form, L4−. Associations with aquated Na+ counterions lead to a pleasingly symmetrical packing arrangement resembling honeycomb, with the central holes of individual metallocycles lined up one above the other. The ligand L4−, on account of its rigid angularity and its strong metal binding properties, promises to provide a rich source of unusual metal-containing structures, in particular cages, in future studies

Highly Symmetric Networks Derived from Cubane-Related Octametallic Complexes of a New Oxyanion of Carbon, C₄O₇^4-, Each Molecule Attached to Eight Neighbors by 24 Equivalent Hydrogen Bonds

Aqueous reaction mixtures containing dihydroxyfumaric acid, M2+ (M = Zn, Co, Fe, and Mg) and acetate ion at room temperature give crystals, suitable for single-crystal X-ray diffraction studies, of composition [(MII)8(C4O7)4(H2O)12]·24H2O, in which the C4O74- component is the alkoxide-tricarboxylate tetra-anionic species -OC(CO2-)3, a new oxyanion of carbon. All four compounds crystallize in the body-centered space group I4̄3m with cell dimensions a ≈ 15.0 Å. Discrete electrically neutral [(MII)8(C4O7)4(H2O)12] molecules are present, with a cubane-like core consisting of four trigonal prismatic metal centers and four μ3-alkoxo bridges from separate -OC(CO2-)3 ligands. The octametallic molecule is highly symmetrical, with four fac tri-aqua octahedral metal centers tetrahedrally appended to the central cubane-based [(MII)8(C4O7)4 ]8- unit. The molecules assemble in the crystal in a body-centered cubic fashion, each being attached to its eight neighbors by 24 equivalent hydrogen bondsan extreme example of self-complementarity

A New Approach to DCNQI-Based Coordination Polymers via DCNQIH₂

Readily available, air-stable DCNQIH2 (i.e., 1,4-NC·NH·C6H4·NH·CN) affords, in a very simple manner, crystals of [Mn(DCNQI)(bridge)]2DMF (where bridge = 4,4′-bipyridine or 1,2-bis(4-pyridyl)ethylene) in which there are [(Mn2+)(DCNQI2−)]n sheets held together by 4,4′-bipyridine or 1,2-bis(4-pyridyl)ethylene pillars. This approach via DCNQIH2 promises convenient general entry into new types of DCNQI-based coordination polymers and could lead to new materials with interesting and possibly useful magnetic/electronic properties

Guanidinium Ion as a Symmetrical Template in the Formation of Cubic Hydrogen-Bonded Borate Networks with the Boracite Topology

Reaction between boric acid and guanidinium salts in methanolic solution at room temperature in the presence of various bases and anions gives well-formed solvated crystals of composition {[B(OCH3)4]3[C(NH2)3]4}+X-. The products in which X- = Cl- and PF6- are characterized by single-crystal X-ray diffraction. The tetramethoxyborate and guanidinium components form a highly symmetrical (cubic) hydrogen-bonded 3D network having the “boracite topology” [i.e., the (63)(6284) topology]. Highly disordered solvent molecules and anions occupy methyl-surfaced cavities and channels that represent more than 30% of the space

A Very Large Metallosupramolecular Capsule with Cube-like 4³ Topology Assembled from Twelve Cu(II) Centers and Eight Tri-Bidentate Tri-Anionic Ligands Derived from 2,4,6-Triphenylazo-1,3,5-trihydroxybenzene <i>J. Am. Chem. Soc.</i> <b>1999</b>, <i>121</i>, 3535−3536

A Very Large Metallosupramolecular Capsule with Cube-like 43 Topology Assembled from Twelve Cu(II) Centers and Eight Tri-Bidentate Tri-Anionic Ligands Derived from 2,4,6-Triphenylazo-1,3,5-trihydroxybenzene J. Am. Chem. Soc. 1999, 121, 3535−353

A New Approach to DCNQI-Based Coordination Polymers via DCNQIH₂

Readily available, air-stable DCNQIH2 (i.e., 1,4-NC·NH·C6H4·NH·CN) affords, in a very simple manner, crystals of [Mn(DCNQI)(bridge)]2DMF (where bridge = 4,4′-bipyridine or 1,2-bis(4-pyridyl)ethylene) in which there are [(Mn2+)(DCNQI2−)]n sheets held together by 4,4′-bipyridine or 1,2-bis(4-pyridyl)ethylene pillars. This approach via DCNQIH2 promises convenient general entry into new types of DCNQI-based coordination polymers and could lead to new materials with interesting and possibly useful magnetic/electronic properties