Fixing a hole: Hydrothermal chemistry has been exploited in the preparation of a 3D framework material exhibiting 48% accessible void volume and 1.5% hydrogen uptake by weight at 120 kPa (see picture). The title compound also exhibits single-chain magnetic behavior and reversible changes in magnetic properties upon solvation and desolvation.

A series of organic-inorganic hybrid materials of the copper(II)-molybdophosphonate family have been prepared using conventional hydrothermal conditions. The reactions of MoO(3), copper(II) acetate, bipyrimidine (bpyr), a phosphonic acid, and water at temperatures below 160 degrees C and in the presence of a mineralizer such as acetic acid or HF provided crystalline samples of materials of the general class {Cu(2)(bpyr)}(4+)/Mo(x)O(y)-phosphonate. The recurrent themes of the structures are the presence of the binuclear {Cu(2)(bpyr)}(4+) and pentanuclear {Mo(5)O(15)(O(3)PR)(2)}(4-) building blocks. For the alkylphosphonate-containing materials, [{Cu(2)(bpyr)(2)}Mo(5)O(15)(O(3)PCH(3))(2)].2.5H(2)O (1.2.5H(2)O) is two-dimensional and exhibits {Cu(bpyr)}(n)(2n+) chains, while [{Cu(2)(bpyr)(H(2)O)}Mo(5)O(15)(O(3)PCH(2)CH(3))(2)] (2) is three-dimensional. The diphosphonate series of materials {{Cu(2)(bpyr)}(4+)[Mo(5)O(15){O(3)P(CH(2))(n)PO(3)}](4-) with n = 2-6 (4, 5, 7-9) in all cases contain the characteristic [Mo(5)O(15){O(3)P(CH(2))(n)PO(3)}](n)(2n+) chains, linked through {Cu(2)(bpyr)}(4+) rods into three-dimensional frameworks. When n = 1, the three-dimensional phase [{Cu(2)(bpyr)}MoO(2)(HO(3)PCH(2)PO(3))(2)].2H(2)O (3.2H(2)O) is obtained, the exclusive example of a structure constructed from isolated {MoO(6)} polyhedra rather than pentamolybdate clusters. The Ni(II)-containing phase [{Ni(2)(bpyr)(H(2)O)(4)}Mo(5)O(15){O(3)P(CH(2))(3)PO(3)}].9H(2)O (6.9H(2)O) was also prepared and compared to the structure of the Cu(II) analogue, [{Cu(2)(bpyr)(H(2)O)(4)}Mo(5)O(15){O(3)P(CH(2))(3)PO(3)}].3H(2)O (5.3H(2)O). Magnetic susceptibility studies of the compounds revealed that the magnetic behavior was consistent in all cases with antiferromagnetically coupled dimers. However, the magnitude of the exchange coupling was clearly dependent on the orientation of the M(II) mean equatorial or basal planes relative to the bipyrimidine plane. Thus, when the metal and bipyrimidine planes are nearly coplanar, the J values are in the -77 to -87 cm(-1) range, while J values of -2 to -5 cm(-1) are observed for the compounds with out-of-plane orientations.

The hydrothermal chemistry of a variety of M(II)SO(4) salts with the tetrazole (Ht) ligands 5,5'-(1,4-phenylene)bis(1H-tetrazole) (H(2)bdt), 5',5''-(1,1'-biphenyl)4,4'-diylbis(1H-tetrazole) (H(2)dbdt) and 5,5',5''-(1,3,5-phenylene)tris(1H-tetrazole) (H(3)btt) was investigated. In the case of Co(II), three phases were isolated, two of which incorporated sulfate: [Co(5)F(2)(dbdt)(4)(H(2)O)(6)]·2H(2)O (1·2H(2)O), [Co(4)(OH)(2)(SO(4))(bdt)(2)(H(2)O)(4)] (2) and [Co(3)(OH)(SO(4))(btt)(H(2)O)(4)]·3H(2)O (3·3H(2)O). The structures are three-dimensional and consist of cluster-based secondary building units: the pentanuclear {Co(5)F(2)(tetrazolate)(8)(H(2)O)(6)}, the tetranuclear {Co(4)(OH)(2)(SO(4))(2)(tetrazolate)(6)}(4-), and the trinuclear {Co(3)(μ(3)-OH)(SO(4))(2) (tetrazolate)(3)}(2-) for 1, 2, and 3, respectively. The Ni(II) analogue [Ni(2)(H(0.67)bdt)(3)]·10.5H(2)O (4·10.5H(2)O) is isomorphous with a fourth cobalt phase, the previously reported [Co(2)(H(0.67)bat)(3)]·20H(2)O and exhibits a {M(tetrazolate)(3/2)}(∞) chain as the fundamental building block. The dense three-dimensional structure of [Zn(bdt)] (5) consists of {ZnN(4)}tetrahedra linked through bdt ligands bonding through N1,N3 donors at either tetrazolate terminus. In contrast to the hydrothermal synthesis of 1-5, the Cd(II) material (Me(2)NH(2))(3)[Cd(12)Cl(3)(btt)(8)(DMF)(12)]·xDMF·yMeOH (DMF = dimethylformamide; x = ca. 12, y = ca. 5) was prepared in DMF/methanol. The structure is constructed from the linking of {Cd(4)Cl(tetrazolate)(8)(DMF)(4)}(1-) secondary building units to produce an open-framework material exhibiting 66.5% void volume. The magnetic properties of the Co(II) series are reflective of the structural building units.

Reichlich Stauraum: Ein hydrothermalchemischer Ansatz führte zu einem Material mit dreidimensionaler Netzwerkstruktur, das 48 % zugängliches Leervolumen enthält und bei 120 kPa Druck 1.5 Gew.‐% Wasserstoff aufnimmt (siehe Bild). Die Titelverbindung ist überdies ein Einzelkettenmagnet, dessen magnetische Eigenschaften sich bei Solvatisierung und Desolvatisierung reversibel verändern.magnified image

The hydrothermal reaction of CuCl 2 3 2H 2 O and 4-(1H tetrazol-5-yl)-benzoic acid (H 2 tba) in the presence of excess HCl yielded the three-dimensional material (Me 2 NH 2 )[Cu 4 Cl(tba) 4 (H 2 O) 4 ] 3 2DMF. The structure is constructed from {Cu 4 (μ 4 -Cl)-(H 2 O) 4 } 7þ clusters linked through tba 2-ligands into an open framework with 57% void volume. The microporosity and magnetic properties of the material were investigated.The contemporary interest in organic-inorganic materials reflects their applications to catalysis, optical materials, membranes, and sorption. 1-10 This diversity of properties reflects a vast compositional range, which is manifested in variations in covalency, geometry, and oxidation states, and a versatile crystalline architecture which provides materials with various dimensionalities, pore sizes and geometries, coordination sites, or juxtapositions of functional groups. The unique characteristics of the organic and inorganic components are combined in a complementary fashion to provide materials with unusual solid-state structures, exhibiting composite or even novel properties, and providing access to a vast area of complex and multifunctional materials. 11,12 An important category of organic-inorganic hybrid materials is the metal-organic frameworks (MOFs) or coordination polymers, in which metal atoms or clusters are linked through polyfunctional organic molecules. 13-15 While materials incorporating carboxylate and pyridine-based ligands have been most extensively studied, 16 more recently attention has focused on polyazoheteroaromatic ligands, such as pyrazolate, imidazolate, triazolate, and tetrazolate, as ligand components. 17-24 Polyazoheteroaromatic ligands have been shown to bridge metal ions to afford polynuclear compounds, to possess superexchange capacity resulting in unusual magnetic properties of the complexes, and to be readily derivatized to incorporate additional functional and/or steric groups.As part of our investigations of synthetic approaches for design of hybrid materials incorporating cluster building blocks, 25 we studied the hydrothermal chemistry of triazole with transition metal cations to provide a facile route to materials with sorptive, magnetic, luminescent, or multifunctional properties. 26-30 Simple ligand modifications were also reflected in the properties of the materials. For example, the sorptive capacity of the three-dimensional (3-D) material [Cu 3 (OH) 3 (trz) 3 (H 2 O) 4 ] 3 4H 2 O was enhanced by the simple expedient of expansion of the ligand tether length in the structurally analogous [Cu 3 (OH) 3 (4-pt) 3 (DMF) 4 ] 3 5DMF 3 3MeOH (Scheme 1). Encouraged by these results and the welldocumented tendency of carboxylate ligands to bridge metal sites in MOFs and to participate in the formation of cluster building blocks, the dipodal multidentate ligand 4-(1H-tetrazol-5-yl)-benzoic acid (H 2 tba) was reacted with CuCl 2 to yield the 3-D framework material (Me 2 NH 2 )[Cu 4 Cl(tba) 4 (H 2 O) 4 ] 3 2DMF. 31 As shown in Figure 1, the 3-D framework o...