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The synthesis and characterization of four new β-ketiminate hafnium(IV) chloride complexes dichloro-bis[4-(phenylamido)pent-3-en-2-one]-hafnium (4a), dichloro-bis[4-(4-methylphenylamido)pent-3-en-2-one]-hafnium (4b), dichloro-bis[4-(4-methoxyphenylamido)pent-3-en-2-one]-hafnium (4c), and dichloro-bis[4-(4-chlorophenylamido)pent-3-en-2-one]-hafnium (4d) are reported. All the complexes (4a–d) were characterized by spectroscopic methods (1H NMR, 13C NMR, IR), and elemental analysis while the compound 4c was further examined by single-crystal X-ray diffraction, revealing that the complex is monomer with the hafnium center in octahedral coordination environment and oxygens of the chelating N–O ligands are trans to each other and the chloride ligands are in a cis arrangement. Volatile trends are established for four new β-ketiminate hafnium(IV) chloride complexes (4a–d). Sublimation enthalpies (ΔHsub) were calculated from thermogravimetric analysis (TGA) data, which show that, the dependence of ΔHsub on the molecular weight (4a–c) and inductive effects from chlorine (4d).

Synthesis and spectral investigation of four novel β-diketiminate hafnium(IV) chloride complexes cis-dichloro-bis(2,4-bis(phenylimino)pent-3-ene)-hafnium (4a), cis-dichloro-bis(2,4-bis(4-methylphenylimino)pent-3-ene)-hafnium (4b), cis-dichloro-bis(2,4-bis(4-methoxyphenylimino)pent-3-ene)-hafnium (4c) and cis-dichloro-bis(2,4-bis(4-chlorophenylimino)pent-3-ene)-hafnium (4d) are reported. All complexes (4a–d) were characterized by spectroscopic methods (1H NMR, 13C NMR and mass) and elemental analysis. The solid-state structure of compound 4a was further examined by single crystal X-ray diffraction. The X-ray structure of 4a reveals that the complex is monomeric with the hafnium center in a distorted octahedral geometry, and the chloride ligands are in a cis arrangement. The thermal stability and volatility of the compounds were probed by TGA/DSC tests demonstrating the potential utility of compounds (4a–d) as precursors for CVD/ALD thin film growth below 200 °C.

β-Enaminones have been synthesized by the condensation reaction of β-diketones with various anilines in the presence of a catalytic amount of formic acid, mild and highly efficient acid catalyst in methanol. These condensation reactions proceed smoothly in short reaction times with near-quantitative yields. Supplemental materials are available for this article. Go to the publisher's online edition of Synthetic Communications® to view the free supplemental file.

The compound (2Z)-3-[(4-methylphenyl)amino]-1-phenylbut-2-en-1-one was synthesized by the condensation reaction of benzoylacetone with p-methylaniline and structurally characterized by 1H NMR, 13C NMR, IR, mass spectrometry, elemental analysis, TGA/DSC and single crystal X-ray diffraction. The title compound crystallizes in the orthorhombic space group Pccn (No. 56) with a = 17.0042(18) A, b = 11.5826(13) A, c = 14.0514(15) A, V = 2767.5(5) A3 and Z = 8. Data collection on 223(2) K resulted its structure with R1 = 0.0449, wR2 = 0.0980. The molecules in the unit cell are arranged in layers. The intramolecular hydrogen bonds of the type N–H···O were observed in the structure. The compound exhibits two distinct endothermic peaks at a temperature 94.70 °C and 232.60 °C corresponding to melting and boiling points respectively. The compound (2Z)-3-[(4-methylphenyl)amino]-1-phenylbut-2-en-1-one was synthesized by the condensation reaction of benzoylacetone with p-methylaniline and structurally characterized by 1H NMR, 13C NMR, IR, mass spectrometry, elemental analysis, TGA/DSC and single crystal X-ray diffraction. The title compound crystallizes in the orthorhombic space group Pccn (No. 56) with a = 17.0042(18) A, b = 11.5826(13) A, c = 14.0514(15) A, V = 2767.5(5) A3 and Z = 8. Data collection on 223(2) K resulted its structure with R1 = 0.0449, wR2 = 0.0980.

Ordered carbonaceous growth typically requires high-energy methods such as arc discharge [1] or decomposition of hydrocarbon-based precursors using laser [2–4], plasma [3], or thermolytic techniques [4]. For the latter technique, temperature regimes on the order of 600–1000° C are most common, with a few recent reports citing lower temperatures using halogenated precursors [5–7], or through alkali-metal catalyzed transformation of bulk carbon allotropes [8,9]. Sailor etal. have reported the first growth of non-amorphous carbon deposits at room temperature [10]. However, their electrochemical synthesis did not produce nanostructural carbon; due to the absence of nanosized catalytic seeds, the diameters of their fibers were > 5μm, and contained copious amounts of Cl, H, N, and O impurities.

We report the deposition of aluminum oxide and aluminosilicate thin films onto carbon fiber substrates, at temperatures of 200° and 250°C, respectively. For aluminosilicate films, the Al/Si ratio of the resultant film varied concomitantly with the composition of the liquid precursor mixture. The growth rate for the oxide films was 15–17 A/min, comparable with other methods carried out at higher temperatures. Cross-section SEM images indicate that the deposited films are conformal, following the complex topography of the carbon fiber substrate. Preliminary gas-phase IR analysis suggests that the coatings decompose the nerve agent simulant dimethyl methylphosphonate at temperatures as low as 35°C, suggesting the utility of the reported methodology for the design/fabrication of actively protective fabrics and clothing.

Reaction of adamantylmagnesium bromide, AdaMgBr (Ada=C 10 H 15 ) with aluminum(III) chloride, gallium(III) chloride, dimethylgallium chloride, or dimethylaluminum chloride gives [Mg 3 BrCl 3 (OEt)(OEt 2 ) 6 ][Ada 3 AlBr] ( I ), [Mg 3 Br 2 Cl 3 (OEt 2 ) 6 ][Ada 2 GaBr 2 ] ( II ), [Mg 3 Br 4 (OEt)(OEt 2 ) 6 ][Ada 2 GaMe 2 ] ( III ), and [Mg 3 Br 4 (OEt)(OEt 2 ) 6 ][Ada 2 AlMe 2 ] ( IV ), respectively. These ionic compounds, characterized by 1 H- and 13 C-NMR, elemental analyses, and single crystal X-ray diffraction, contain trimetallic magnesium cations with each alkaline earth metal residing in a distorted octahedral environment. The aluminum and gallium atoms in the adamantyl-based anions reside in distorted tetrahedral environments. These substances are the first examples of adamantyl-based Group 13 organometallic compounds.

DFT (B3LYP) and MP2 computations with a 6-31G* basis set show that a unique protoadamantane radical cation (1·+) structure with an elongated, half-broken C6−H bond prevails both in the gas phase and in solution. This is in agreement with the observed regioselectivity of the single electron-transfer oxidation of protoadamantane (1) with photoexcited 1,2,4,5-tetracyanobenzene, which only gives 5-(6-protoadamantyl)-1,2,4-tricyanobenzene (5), for which the X-ray crystal structure is reported. The regioselectivities for the functionalizations of 1 with electrophiles support this oxidation pathway. The H-coupled electron-transfer mechanism recently proposed for the C−H activation of alkanes with electrophilic oxidizers explains the high C6 positional selectivities in the functionalization of 1 in electrophilic media. (© Wiley-VCH Verlag GmbH, 69451 Weinheim, Germany, 2002)

Tris(pentamethylphenyl)gallium, (Me5C6)3Ga, was prepared by reaction of pentamethylphenylmagnesium bromide with gallium(III) chloride in diethyl ether. The title compound, characterized by 1H and 13C NMR, elemental analyses, and single crystal X-ray diffraction, crystallizes in the P 1 (No. 2) space group with a=9.003(9) A, b=10.713(1) A, c=16.066(2) A, α=107.63 (3)°, β=97.63 (3)°, γ=90.08(3)°, for Z=2. Refinement converged at R1=0.050, wR2=0.11. The pentamethylphenyl ligands are configured about the gallium center in a propeller fashion at angles of 67.3°, 62.3°, and 60.9°.

The synthesis and molecular structures of tris(pentamethylphenyl)aluminum, (C6Me5)3Al, (I), and the magnesium cluster [Mg6(μ3-OH)2(μ3-Br)2(μ2-Br)8(OEt2)8] (II), are reported. Both compounds were isolated from the same system. The aluminum atom in (I) resides in an almost idealized trigonal planar environment. The dihedral angles of the pentamethylphenyl rings relative to the AlC3plane in (I) are 67.2, 62.4, and 61.2°. The neutral magnesium cluster, (II), is interesting in that contains six magnesium atoms each of which resides in octahedral environments.

Reaction of 1,4-dilithiotetraphenylbutadiene with boron bromide affords the novel organoborane derivative [(PhC)8C2H5]B (1) as yellow crystals characterized by 1H, 13C NMR, elemental analyses, and single crystal X-ray diffraction. The title compound (1) crystallizes in the monoclinic space group P21/n, with cell parameters a = 15.519(10) A, b = 12.240(6) A, c = 25.497(16) A, β = 95.369(10)°. Refinement converged at R = 0.0718. The average B–C bond distance in the title compound is 1.560 A. An unusual structural feature of the title compound is the presence of an ethyl group that was probably abstracted from the diethyl ether solvent.

Chemical vapor deposition (CVD) is a process routinely used to produce thin films of materials via decomposition of volatile precursor molecules. Unfortunately, the equipment required for a conventional CVD experiment is not practical or affordable for many undergraduate chemistry laboratories, especially at smaller institutions. In an effort to expose undergraduate chemistry students to this valuable materials science technique, a convenient, inexpensive apparatus was constructed to deposit thin films of aluminum oxide on a silicon wafer substrate. The system features the controlled hydrolysis of the water-sensitive precursor liquid, dimethylaluminumisopropoxide, at 200 °C. The experiment described herein is customizable depending on the resources available and lends itself to an inquiry-based format. A discussion of overall student sentiment and pedagogical outcomes from this module is also included.

β-Enaminones have been synthesized by the condensation reaction of β-diketones with various anilines in the presence of a catalytic amount of formic acid, mild and highly efficient acid catalyst in methanol. These condensation reactions proceed smoothly in short reaction times with near-quantitative yields. Supplemental materials are available for this article. Go to the publisher's online edition of Synthetic Communications® to view the free supplemental file.

The dendritic architecture represents the fourth major class of polymers. Though hyperbranched polymers and structurally-perfect dendrimers (e.g., poly(amidoamine), PAMAM) both share this designation, the latter are of greater use for nanoreactor applications. One such application that exploits the container/reactor properties of dendrimers is the controlled growth of nanoclusters. Herein, we provide a review of the recent synthetic methods for nanocluster growth using a dendritic host, and their use in a variety of applications. The benefits of using this macromolecular host will also be discussed, within a historical context of colloidal entraining agents.

In the title compound, [Ga(C12H18N2O2)Cl], the Ga atom is coordinated to a Cl atom and the two imine N and two enolate O atoms of the Schiff base ligand. The literature reveals few examples of a five-coordinate GaO2N2Cl environment, and only two where both the N and the O atoms are contained within the same ligand. This configuration has the effect of constraining the complex into a square-pyramidal geometry with less distortion than if formed by two or more ligands. The Ga—N and Ga—O distances are within the ranges expected for Ga–Schiff base derivatives. This compound is also the first group 13 complex containing the N,N′-ethyl­ene­bis­(acetyl­acetoneimine) (acacen) ligand.

We describe the growth of amorphous carbon nanofibers (CNFs) from iron-encapsulated dendrimer catalysts at ambient temperature and pressure conditions. Both fourth-generation poly (propyleneimine) (PPI) and poly(amidoamine) (PAMAM) dendrimers were suitable macromolecular hosts for the catalytic species. Average nanofiber diameters range from 10 - 15 nm, with lengths in excess of 20 microns.

[reaction: see text] The p-benzoquinone shown is converted to the novel hexacyclic triterpene salvadione-A in four steps.

Pseudotetrahedral, conformationally as well as configurationally stable 1-bromo-3-chloro-5-fluoro- (4) and 1-bromo-3-chloro-5-fluoro-7-iodoadamantane (5) (and some related compounds) were prepared by our recently devised phase-transfer catalytic halogenation protocol; the optical antipodes of 4 were separated by HPLC on chiral phase in ee > 99%, and the absolute configurations were assigned by matching observed and computed circular dichroism spectra. Structure 5 is the first chiral aliphatic hydrocarbon containing all stable (nonradioactive) halogens; its structure was proven by NMR spectroscopy and by X-ray crystal data. We emphasize that the combination of experiment and theory is very powerful in assigning absolute configurations even for molecules without typical chromophors, with small values for the optical rotation, and without an atom at the stereogenic center.

Multiwall carbon nanotubes (MWNTs) were synthesized via the decomposition of CCl4 in supercritical CO2 at 175 degrees C and 27.6 MPa using an iron-encapsulated dendrimer as a growth catalyst. The average diameter of resultant nanotubes was 20-25 nm, obtained after a 24-h reaction time. Our conditions represent the first application for CX4 precursors, as well as the lowest-reported temperature regime for carbon nanotube growth, allowing the use of other temperature-sensitive catalytic substrates.

Reaction of 1,4-dilithiotetraphenylbutadiene with phosphorus(III) bromide affords bis(tetraphenylbutadienyl)diphosphine, (Ph4C4)P–P(C4Ph4), with a phosphorus–phosphorus bond length of 2.2051(11) A.

Though the diversity of applications involving supercritical fluids (SCFs) continue to mount in virtually every sector of the scientific workplace, this environmentally-friendly medium is only briefly mentioned in undergraduate curricula; most often without hands-on laboratory experience. A new experimental module featuring this technology was introduced into an undergraduate inorganic chemistry laboratory. Nanoparticles of copper and aluminum oxide were formed using a variety of novel procedures, with scanning electron microscopy (SEM–EDS) and transmission electron microscopy (TEM) utilized for characterization. While particles of aluminum oxide were found to average 100 nm with sufficient aggregation, the copper nanoparticles were much smaller in diameter, with less agglomeration. A discussion of overall student sentiment and pedagogical outcomes from this module is also provided.