Open-framework metal phosphates occur as one-dimensional (1D) chains or ladders, two-dimensional (2D) layers, and complex three-dimensional (3D) structures. Zero-dimensional monomers have also been isolated recently. These materials are traditionally prepared by hydrothermal means, in the presence of organic amines, but the reactions of amine phosphates with metal ions provide a facile route for the synthesis, and also throw some light on the mode of formation of these fascinating architectures. Careful studies of the transformations of monophasic zinc phosphates of well-characterized structures show that the 1D structures transform to 2D and 3D structures, while the 2D structures transform to 3D structures. The zero-dimensional monomers transform to 1D, 2D, and 3D structures. There is reason to believe that the 0D monomers, comprising four-membered rings, are the most basic structural units of the open-framework phosphates and that after an optimal precursor state, such as the ladder structure, is formed, further building may occur spontaneously. Evidence for the occurrence of self-assembly in the formation of complex structures is provided by the presence of the structural features of the one-dimensional starting material in the final products. These observations constitute the beginning of our understanding of the building-up principle of such complex structures.

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A Cu(I) catalyst (1), supported by a framework of strongly basic guanidinato moieties, mediates nitrene-transfer from PhI═NR sources to a wide variety of aliphatic hydrocarbons (C-H amination or amidination in the presence of nitriles) and olefins (aziridination). Product profiles are consistent with a stepwise rather than concerted C-N bond formation. Mechanistic investigations with the aid of Hammett plots, kinetic isotope effects, labeled stereochemical probes, and radical traps and clocks allow us to conclude that carboradical intermediates play a major role and are generated by hydrogen-atom abstraction from substrate C-H bonds or initial nitrene-addition to one of the olefinic carbons. Subsequent processes include solvent-caged radical recombination to afford the major amination and aziridination products but also one-electron oxidation of diffusively free carboradicals to generate amidination products due to carbocation participation. Analyses of metal- and ligand-centered events by variable temperature electrospray mass spectrometry, cyclic voltammetry, and electron paramagnetic resonance spectroscopy, coupled with computational studies, indicate that an active, but still elusive, copper-nitrene (S = 1) intermediate initially abstracts a hydrogen atom from, or adds nitrene to, C-H and C═C bonds, respectively, followed by a spin flip and radical rebound to afford intra- and intermolecular C-N containing products.

Five new open-framework zinc phosphates, encompassing the entire hierarchy of open-framework structures, have been synthesized hydrothermally in the presence of triethylenetetramine. The structures include one-dimensional ladders, two-dimensional layers, and three-dimensional structures as well as a zinc phosphate where the amine acts as a ligand. [C6N4H22]0.5[Zn(HPO4)2] (I): monoclinic, space group P2(1)/c (no. 14), a = 5.2677(1) A, b = 13.3025(1) A, c = 14.7833(1) A, beta = 96.049 degrees, Z = 4. [C6N4H22]0.5[Zn2(HPO4)3] (II): triclinic, space group P1 (no. 2), a = 7.515(1) A, b = 8.2553(1) A, c = 12.911(1) A, alpha = 98.654(1) degrees, beta = 101.274(1) degrees, gamma = 115.791(1) degrees, Z = 2. [C6N4H22]0.5[Zn2P2O8] (III): triclinic, space group P1 (no. 2), a = 8.064(1) A, b = 8.457(1) A, c = 9.023(1) A, alpha = 111.9(1) degrees, beta = 108.0(1) degrees, gamma = 103.6(1) degrees, Z = 2. [C6N4H22]0.5[Zn3(PO4)2(HPO4)] (IV): triclinic, space group P1 (no. 2), a = 5.218(1) A, b = 8.780(1) A, c = 16.081(1) A, alpha = 89.3(1) degrees, beta = 83.5(1) degrees, gamma = 74.3(1) degrees, Z = 2. [C6N4H20]0.5[Zn4P4O16] (V): monoclinic, space group P2(1)/c (no. 14), a = 9.219(1) A, b = 15.239(1) A, c = 10.227(1) A, beta = 105.2(1), Z = 4. The structure of I is composed of ZnO4 and HPO4 tetrahedra, which are edge-shared to form four-membered rings, which, in turn, form a one-dimensional chain (ladder). In II, these ladders are fused into a layer. The structures of III and IV comprise networks of ZnO4 and PO4 tetrahedra forming three-dimensional architectures. In V, the amine molecule coordinates to the Zn and acts as a pillar supporting the zinc phosphate layers, which possess infinite Zn-O-Zn linkages. The 16-membered one-dimensional channel in IV and the ZnO3N pillar, along with infinite Zn-O-Zn linkages in V, are novel features. The structure of the open-framework zinc phosphates is found to depend sensitively on the relative concentrations of the amine and phosphoric acid, with high concentrations of the latter favoring structures with lower dimensions.

Selective amination of σ and π entities such as C–H and CC bonds of substrates remains a challenging endeavor for current catalytic methodologies devoted to the synthesis of abundant nitrogen-containing chemicals. The present work addresses an approach toward discriminating aromatic over aliphatic alkenes in aziridination reactions, relying on the use of anionic metal reagents (M = Mn, Fe, Co, Ni) to attenuate reactivity in a metal-dependent manner. A family of MnII reagents bearing a triphenylamido-amine scaffold and various pendant arms has been synthesized and characterized by various techniques, including cyclic voltammetry. Aziridination of styrene by PhINTs in the presence of each MnII catalyst establishes a trend of increasing yield with increasing MnII/III anodic potential. The FeII, CoII, and NiII congeners of the highest-yielding MnII catalyst have been synthesized and explored in the aziridination of aromatic and aliphatic alkenes, exhibiting good to high yields with para-substituted styrenes, low to modest yields with sterically congested styrenes, and invariably low yields with aliphatic olefins. CoII mediates faster styrene aziridination in comparison to MnII but is less selective than MnII in competitive aziridinations of conjugated versus nonconjugated olefins. Indeed, MnII proved to be highly selective even versus well-established copper and rhodium aziridination reagents. Mechanistic investigations and computational studies indicate that all metals follow a two-step styrene aziridination pathway (successive formation of two N–C bonds), featuring a turnover-limiting metal–nitrene addition to an olefinic carbon, followed by product-determining ring closure. Both steps exhibit activation barriers in the order Fe > Mn > Co, most likely stemming from relevant metal–nitrene electrophilicities and MII/III redox potentials. The aziridination of aliphatic olefins follows the same stepwise path, albeit with a considerably higher activation barrier and a weaker driving force for the formation of the initial N–C bond, succeeded by ring closure with a miniscule barrier.

Two new ternary materials NaGaS 2 (1) and the Fedoped phase of NaGaS 2 , NaFe 0.135 Ga 0.865 S 2 (2), have been synthesized by employing polysulfide flux. Single crystal XRD analyses of 1 and 2 show that the structure is built up of adamantane-like Ga 4 S 10 super tetrahedral fundamental building units. These admantane-like units are connected through their corners to form [GaS 2 ] ∞ − layers that are stacked one over the other with Na ions residing in between the layers to balance the charge. Both the materials have the remarkable ability to absorb atmospheric water molecules and moisture from undried solvents as verified by TG analysis and FT-IR and XPS studies. The process of water absorption leads to stable distinct material) with restacked layers different from original crystal structure. This structural transformation is reversible as the transformed structures 1•H 2 O and 2•H 2 O can be returned to their original structures 1 and 2, respectively, upon heating. DFT calculation study reveals that a spontaneous exergonic hydration reaction takes place as outlined in NaGaS 2 + H 2 O → NaGaS 2 •H 2 O with the energy release, ΔE of −73.9 kJ mol −1 . DFT calculation predicts an increase in the unit cell parameters of b and c directions and shrinkage along the a direction of hydrated phase 1•H 2 O with an overall volume increase of 36.6%. Structural transformation affects their physical properties as the pristine compound 1 possess Na + ion conductivity of 2.88 × 10 −7 S cm −1 at 22 °C, whereas the hydrated compound 1•H 2 O displays ∼40 times increased ion conductivity of 1.25 × 10 −5 S cm −1 at the same temperature. DRS studies show very similar optical band gaps of ∼4 eV for compounds 1 and 1•H 2 O, respectively, in reasonable agreement with the DFT(HSE) band gap estimation but more than 1 eV above the DFT(PBE)-predicted band gaps of ∼2.4 eV. A sorption study indicates selective adsorption of water over MeOH, EtOH, and CH 3 CN with a maximum water uptake of 2.6 H 2 O per formula unit at P/P 0 = 0.9. A Karl Fischer titration study shows that NaGaS 2 (1) is certainly capable of adsorbing water from wet methanol and can be useful as a fast desiccating agent.

equipped with a 150 lines mm ±1 grating and registered by an optical multichannel analyzer (OMA, Hamamatsu Photonics, PMA50 Synthesis and Characterization of Magnetic Iron Sulfide NanowiresBy Manashi Nath, Amitava Choudhury, Asish Kundu, and C. N. R. Rao* A variety of inorganic nanowires have been synthesized in the last three to four years.[1] Among these, magnetic nanowires are of interest because of their potential applications in magnetic recording and other areas. Nanowires and nanorods of magnetic metals, such as Fe, Co, and Ni, [2] and their alloys [3] have been prepared by employing template-directed synthesis. Although there are reports of nanotubes, nanorods, and nanowires of several metal chalcogenides, [4,5] oxides, [6] and nitrides [1,6] there is no report to date on iron sulfide nanowires, possibly because of the inherent difficulty in the synthesis and control of stoichiometry of these materials. The Fe±S system has a complex phase diagram, with broad range of compositions of Fe 1±x S (pyrrhotite) phases [7] occurring between FeS and FeS 2 , showing interesting magnetic [8±10] and electrical properties.[11] Fe 7 S 8 is a well-defined phase in this region,showing ferrimagnetism with T N = 600 K. [9] We deemed it important to synthesize iron sulfide nanowires by virtue of their interesting chemistry and magnetic properties. In this communication, we report the first successful synthesis of semiconducting nanowires of Fe 1±x S (x » 0.12, 0.09), of which the Fe 0.88 S (Fe 7 S 8 ) nanowires are ferrimagnetic, showing magnetic hysteresis at room temperature. In order to synthesize Fe 1±x S nanowires, a hybrid composite (I) with ethylenediamine was first prepared by solvothermal procedure (see Experimental). Scanning electron microscopy (SEM) and transmission electron microscopy (TEM) images of the composite I showed the presence of a high yield of lengthy nanowires with diameters in the range of 80±150 nm and lengths of several micrometers as shown in Figure 1. The infrared (IR) spectrum showed characteristic peaks of the amine, although the bands due to C±N and N±H stretching frequencies were considerably shifted towards lower values due to the bound nature of the amine. Energy dispersive X-ray (EDX) analysis of several samples of I carried out over different regions of each sample gave an average Fe/S ratio of Fig. 1. a) SEM image of the organic±inorganic composite, Fe 1±x S(en) 0.5 , I. b) Low-magnification TEM image of composite I. Apart from nanowires, some layer-rolled kind of structures are also observed (as seen in the center of the image).

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