A rare lithium indium siloxane: Synthesis and crystal structure of [InMe{(OPh2Si)(2)O}(2)-mu-{Li(THF)(2)}(2)]

The reaction between lithium tetramethylindate Li[InMe4] and disilanol [(Ph2SiOH)(2)O] yields [InMe-{(OPh2Si)(2)O}(2)-mu-{Li(THF)(2)}(2)] (1). Compound 1 can also be prepared starting from Ph2Si(OH)(2) and Li[InMe4] in good yields. The product has been characterized by elemental analysis and IR and multinuclear NMR spectroscopic studies (H-1, Li-7, and Si-29 NMR). The solid-state structure of 1, determined by single-crystal X-ray crystallography, reveals that the central indium atom 1 is surrounded by four oxygen atoms of the two disilanolate ligands and a methyl group in a square-pyramidal geometry. The InO4C coordination environment observed in 1 is rare among organometallic compounds of indium. The indium atom lies 0.59 Angstrom above the rectangular plane formed by the four oxygens of the silanolate ligands

Synthesis and characterization of new (chloro)aminosilanes: X-ray crystal structure of [(2,6-Me2C6H3NH)(2)SiCl2]

Starting from racemic alpha -methylbenzyl amine or alpha -methylbenzyl bromide, new (amino)trichlorosilanes (MePhC(H))(SiMe3)NSiCl3(1) and (MePhC(H))(2,6-Me2C6H3) NSiCl3 (2) have been synthesized in good yields. The products have been characterized by analytical and IR, mass, and NMR (H-1 and Si-29) spectroscopic techniques. The diamino-dichlorosilane (2,6-Me2C6H3NH)(2)SiCl2 (3) obtained as the side product during the synthesis of 2 has been characterized by a single crystal X-ray diffraction study

Stabilization of p-block organoelement terminal hydroxides, thiols, and selenols requires newer synthetic strategies

Metal hydroxides represent a very interesting and highly useful class of compounds that have been known to chemists for a very long time. While alkali and alkaline earth metal hydroxides (s-block) are commonplace chemicals in terms of their abundance and their use in a chemical laboratory as bases, the interest in Bronsted acidic molecular terminal hydroxides of p-block elements, such as aluminum and silicon, has been of recent origin, with respect to the variety of applications these compounds can offer both in materials science and catalysis. Moreover, these systems are environmentally friendly, relative to the metal halides, owing to their -OH functionality (resembling that of water). Design and conceptualization of the corresponding terminal thiols, selenols, and tellurols (M-SH, M-SeH, and M-TeH) offer even more challenging problems to synthetic inorganic chemists. This concept summarizes some of the recent strategies developed to stabilize these otherwise very unstable species. The successful preparation of a number of silicon trihydroxides a few years back resulted in the generation of several model compounds for meta I-silicates. The recent synthesis of unusual aluminum compounds such as RAl(OH)(2), RAl(SH)(2), and RAl(SeH)(2) with terminal EH (E=O, Se, or Se) groups is likely to change the ways in which some of the well-known catalytic conversions are being carried out. The need for very flexible and innovative synthetic strategies to achieve these unusual compounds is emphasized in this concept

Containment of Polynitroaromatic Compounds in a Hydrogen Bonded Triarylbenzene Host

Co-crystallization of energetic materials has emerged as an important technique to modify their critical properties such as stability, sensitivity, etc. Using 1,3,5-tris(4'-aminophenyl)benzene (TAPB) as a novel co-crystal former, we have prepared co-crystals of 2,4,6-trinitrotoluene (TNT), 2,4,6-trinitrophenol (TNP), and m-dinitrobenzene (mDNB). Molecular structures of the co-crystals have been determined from single crystal X-ray diffraction data. The diffraction data analysis reveals that strong intermolecular pi-pi interaction directs the intercalation of polynitroaromatic explosives (PNACs) between the layers of TAPB molecules, which leads to the formation of vertically overlapped -A-B-A-B- types of p-stacks. Both TNT and TNP form p-interactions with the center of TAPB with 1:1 molar ratios, while mDNB forms a complex in a 1:3 stoichiometry through stacking between peripheral rings. The crystal lattices are further stabilized through interstack hydrogen bonds (NH...N and NH...O) between amino groups of TAPB and nitro groups of PNACs. NMR and Fourier transform infrared spectra further provide the information about the presence of various interactions in the crystal systems. Owing to the p electron-rich nature and ease of synthesis, triphenylbenzene systems are promising host candidates for co-crystallization of PNAC analytes

Di-tert-butyl phosphate complexes of cobalt(II) and zinc(II) as precursors for ceramic M(PO(3))(2) and M(2)P(2)O(7) materials: Synthesis, spectral characterization, structural studies, and role of auxiliary ligands

Reaction of the metal acetates M(OAc)(2). xH(2)O with di-tert-butyl phosphate (dtbp-H) (3) in a 4:6 molar ratio in methanol or tetrahydrofuran followed by slow evaporation of the solvent results in the formation of metal phosphate clusters [M(4)(mu (4)-O)(dtbp)(6)] (M = Co (4, blue); Zn (5, colorless)) in nearly quantitative yields. The same reaction, when carried out in the presence of a donor auxiliary ligand such as imidazole (imz) and ethylenediamine (en), results in the formation of octahedral complexes [M(dtbp)(2)(imz)(4)] (M = Co (6); Ni (7); Zn (8)) and [Co(dtbp)(2)-(en)(2)] (9). The tetrameric clusters 4 and 5 could also be converted into mononuclear 6 and 8, respectively, by treating them with a large excess of imidazole. The use of slightly bulkier auxiliary ligand 3,5-dimethylpyrazole (3,5-dmp) in the reaction between cobalt acetate and 3 results in the isolation of mononuclear tetrahedral complex [Co(dtbp)(2)(3,5-dmp)(2)] (10) in nearly quantitative yields. Perfectly air- and moisture-stable samples of 4-10 were characterized with the aid of analytical, thermoanalytical, and spectroscopic techniques. The molecular structures of the monomeric pale-pink compound 6, colorless 8, and deep-blue 10 were further established by single-crystal X-ray diffraction studies. Crystal data for 6: C(28)H(52)CoN(8)O(8)P(2), a = 8.525(1) Angstrom, b = 9.331(3) Angstrom, c = 12.697(2) Angstrom, alpha = 86.40(2)degrees, beta = 88.12(3)degrees, gamma = 67.12(2)degrees, triclinic, P (1) over bar, Z = 1. Crystal data for 8: C(28)H(52)N(8)O(8)P(2)Zn, a = 8.488(1) Angstrom, b = 9.333(1) Angstrom, c = 12.723(2) Angstrom, alpha = 86.55(1)degrees, beta = 88.04(1)degrees, gamma = 67.42(1)degrees, triclinic, P (1) over bar, Z = 1. Crystal data for 10: C(26)H(52)CON(4)O(8)P(2), a = b = 18.114(1) Angstrom, c = 10.862(1) Angstrom, tetragonal, P4(1), Z = 4. The Co(2+) ion in 6 is octahedrally coordinated by four imidazole nitrogens which occupy the equatorial positions and oxygens of two phosphate anions on the axial coordination sites. The zinc derivative 8 is isostructural to the cobalt derivative 6. The crystal structure of 10 reveals that the central cobalt atom is tetrahedrally coordinated by two phosphate and two 3,5-dmp ligands. In all structurally characterized monomeric compounds (6, 8, and 10), the dtbp ligand acts as a monodentate, terminal ligand with free P=O phosphoryl groups. Thermal studies indicate that heating the samples at 171 (for 4) or 93 degreesC (for 5) leads to the loss of twelve equivalents of isobutene gas yielding carbon-free [M(4)(mu (4)-O)(O(2)P(OH)(2))(6)], which undergoes further condensation by water elimination to yield a material of the composition Co(4)O(19)P(6) This sample of 4 when heated above 500 degreesC contains the crystalline metaphosphate Co(PO(3))(2) along with amorphous pyrophosphate M(2)P(2)O(7) in a 2:1 ratio. Similar heat treatment on samples 6-8 results in the exclusive formation of the respective metaphosphates Co(PO(3))(2), Ni(PO(3))(2), and Zn(PO(3))(2); the tetrahedral derivative 10 also cleanly converts into Co(PO(3))(2) On heating above 600 degreesC

Is water a friend or foe in organometallic chemistry? The case of group 13 organometallic compounds

This Account summarizes the recent developments in the hydrolysis chemistry of Group 13 trialkyl and triaryl compounds. Emphasis has been placed on the results obtained by us on (a) H-1 NMR investigations of controlled hydrolyses of AlMes(3) and GaMes(3), (b) low-temperature isolation of water adducts of triaryl compounds of aluminum and gallium, (c) synthesis and structural characterization of new polyhedral alumoxanes and galloxanes, and (d) the search for an easy way to synthesize well-defined crystalline methylalumoxanes by deprotonation of the hydroxides with alkyllithium reagents. The systematic studies on the hydrolysis of tBu(3)-Al carried out by Barren et al. are also discussed in order to elucidate the roles of (i) reaction temperature, (ii) solvent medium, and (iii) source of water molecules, in building up hitherto unknown alumoxane clusters. The role of water impurity in organometallic reactions involving a Group 13 alkyl and other ligands (such as silanetriols and phosphorus acids) to build molecular clusters has also been discussed

First examples of metal cyclohexylphosphonates: Influence of the choice of synthetic route on the product

The first divalent metal cyclohexylphosphonate derivative, [CO(O3PCy)-H2O](n) (1) has been synthesized using four different synthetic methodologies in the presence of added amines. The new phosphonates have been characterized with the aid of analytical, thermoanalytical, spectroscopic, and powder XRD studies. The nature and particle size of the product formed is highly dependent on the method employed (viz. (a) room temperature synthesis, (b) hydrothermal synthesis, (c) microwave assisted synthesis, and (d) a biphasic reaction) as revealed by SEM and TEM studies. While in most cases the metal phosphonates were isolated as insoluble crystalline powders directly from the reaction mixture, the use of 3,5-dimethylpyrazole (DMP) as co-ligand leads to the isolation of soluble compound [{Co(H2O)(4)(DMP)(2)} {CYPO3H}(2)](n) (2) as single crystals. The X-ray diffraction studies on 2 reveal a hydrogenbonded polymeric structure for this compound. Crystal data: C22H48CoN4O10P2, monoclinic, P2(1)/c, a = 12.147(2), b = 11.607(2), c = 11.872(2) angstrom, beta = 104.00(3)degrees, V = 1624.2(5) angstrom(3), Z = 2, R1 (all data) = 0.050, wR2 (all data) = 0.145