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A new ambient-temperature, catalyst-free reaction between ammonia borane and tetrahydrofuran borane produces aminodiborane via the formation of a dihydrogen bond and subsequent molecular hydrogen elimination. The facile synthesis of aminodiborane will make this long-sought active chemical reagent readily available for both inorganic and organic reactions. From aminodiborane, an inorganic butane analogue, NH3BH2NH2BH3, was prepared, and its single-crystal structure displayed a gauche rather than an anti form conformation.

Compound 1 (Mg(H2O)6B10H10·4H2O) was synthesized and characterized using NMR, IR, XRD, and elemental analysis. Its thermal decomposition behavior was studied using Simultaneous Thermogravimetric Modulated Beam Mass Spectrometry (STMBMS), TGA, DSC, IR, and 11B NMR. The crystal structure of 1reveals multiple dihydrogen and hydrogen bonding interactions that form a 3D extended structure. A reaction network characterizing the thermal decomposition of 1and its secondary products over a temperature range from 20 to 1000 °C has been developed. Thermal decomposition of 1is primarily controlled by two competing branches in the reaction network, where coordinated water evolves as either H2O (dehydration) or H2(dehydrogenation). The extent of reaction to form H2depends on the fraction of the coordinated water remaining in the sample when its temperature is between 160 and 225 °C. The evolution of coordinated water is reversible and controlled by dissociative sublimation. For the release of coordinated water between 160 and 215 °C, the vapor pressure of water is given by LogeP(Torr) = 30.4561 – 12425.2/T(K) and ΔHs= 103.3 ± 0.3 kJ/mol. The nature of the condensed phase secondary product remaining after all coordinated water is removed by either dehydration and/or dehydrogenation depends strongly on the extent of reaction to form Mg(OH)xB10H10–x. Results of STMBMS experiments where xvaries from 0.2 to ∼4 are used to develop the reaction network that characterizes the thermal decomposition process. Heating of 1at 205 °C resulted in the formation of water-soluble Mg(OH)x(H2O)2–xB10H10–x, while prolonged heating of 1at 270 °C and heating up to 1000 °C led to decomposition.

Chains of cages: Neutral/ionic [B12H12]2−boron‐cage‐functionalized methacrylate and styrene homopolymers or copolymers (see picture) are non‐crystalline solids, Tgincreases as the number of B12cages in the chain of polystyrene increases, and homopolymers retain more weight than the copolymers when heated to 400 °C.

Solvated potassium salts of the 9-BBN hydroborate anion have been prepared and their structures have been determined by single-crystal X-ray diffraction analyses. A tetrameric complex {LK[(μ-H)2BC8H14]}4 is formed when L is toluene, MeTHF, toluene/THF, THF/Et2O mixtures. The basic framework consists of a distorted K4B4 cube in which potassium and boron are at alternate corners of the cube linked by bridging hydrogen atoms and α-C–H hydrogen atoms from the 9-BBN hydroborate that appear to form agostic interactions with potassium. There are two types of bridging hydrogen atoms: one is connected to three potassium atoms and one boron atom in a μ4-coordination arrangement, and the other one is connected to two potassium atoms and one boron atom in a μ3-coordination arrangement. There are four μ4-hydrogen arrangements in the structure. They are located inside of the K4B4 cube. The four μ3-hydrogen arrangements are located outside of the distorted K4B4 cube. The coordination number of potassium is 8 with the three μ4-, two μ3-bridging hydrogen atoms, two α-C–H hydrogen atoms, and one oxygen atom of the solvent, L (there is a weak π-η6 interaction when the solvent is toluene). On the other hand, in the chelating solvent DME, a dimeric structure is formed in which the inner part is planar with potassium and boron located at alternate corners. The potassium is connected to four μ3-bridging hydrogen atoms, two apparent agostic α-C–H bonding hydrogen atoms, and four oxygen atoms of two DME molecules. Its coordination number is 10 including the agostic interactions. The structure of the uncoordinated [H2BC8H14]– anion is observed in the tetramethylammonium salt. (© Wiley-VCH Verlag GmbH & Co. KGaA, 69451 Weinheim, Germany, 2007)

The structures of n‐B18H22and of n‐B18H22⋅C6H6were determined by single‐crystal X‐ray analysis at −60 °C. The geometry of the boron cluster itself does not seem to be appreciably affected by solvation. There does, however, appear to be an unusual interaction of a polyborane bridging hydrogen atom with the benzene π system, giving rise to an extended stacked structure. The 1H{11B} spectrum of n‐B18H22in [D6]benzene differs from that in [D12]cyclohexane most noticeably in the bridging proton region. Upon moving from the aliphatic to the aromatic solvent, the greatest increase in shielding was for the signal corresponding to the bridge hydrogen atom that interacts with the π system of benzene; the signal was shifted upfield by 0.49 ppm. Density functional theory calculations were performed on 1:1 and 2:1 complexes of the n‐B18H22unit with benzene.

The preparation and chemistry of bis- and tris-mercaptoborates based on closo-B12and closo-B10structures is described. These species undergo a number of reactions such as halogenation and alkylation without changing the closo-borane core. Addition of the third dimethylsulfide substituent to the closo-boranes is thought to proceed via an unusual cationic intermediate.

A 5% w/w palladium loading on silica has been achieved via impregnation of the support with Pd(C2H3O2)2and { (DMF)10Yb2[Pd(CN)4]3} ∞precursors to deliver monometallic (Pd/SiO2) and bimetallic (Yb–Pd/SiO2) catalyst systems respectively. The catalytic action of each has been assessed in the continuous gas‐phase hydrodechlorination (HDC) of chlorobenzene (CB) and 1,2‐dichlorobenzene (1,2‐DCB) (T= 423 K, inlet chlorine/palladium mol ratio of 5 × 103h−1) and the hydrogenation of benzene (T= 423 K, inlet C6H6/palladium mol ratio of 35 h−1). Activation of both catalysts delivered similar palladium crystallite size distributions with an average palladium diameter of 5–6 nm where the ytterbium component (in Yb–Pd/SiO2) was present as a thin surface coating. The Pd–Yb bimetallic exhibited significantly higher HDC and hydrogenation activities, the former manifested by significantly greater fractional dechlorinations and benzene selectivities/yields. Yb/SiO2proved inactive in terms of promoting hydrogen scission or addition and the promotional effect of ytterbium in Yb–Pd/SiO2is discussed in terms of electron donation and hydrogen transfer via surface YbH2. Under identical reaction conditions, a lower HDC activity was recorded for 1,2‐DCB compared with CB, a response that is attributed to steric constraints allied to the deactivating effect of the second chlorine substituent. Both Pd/SiO2and Yb–Pd/SiO2exhibited a decline in HDC activity with time‐on‐stream, but the bimetallic was significantly more resistant to deactivation. Copyright © 2003 John Wiley & Sons, Ltd.

A 5% w/w palladium loading on silica has been achieved via impregnation of the support with Pd(C2H3O2)2 and { (DMF)10Yb2[Pd(CN)4]3} ∞ precursors to deliver monometallic (Pd/SiO2) and bimetallic (Yb–Pd/SiO2) catalyst systems respectively. The catalytic action of each has been assessed in the continuous gas-phase hydrodechlorination (HDC) of chlorobenzene (CB) and 1,2-dichlorobenzene (1,2-DCB) (T = 423 K, inlet chlorine/palladium mol ratio of 5 × 10³ h⁻¹) and the hydrogenation of benzene (T = 423 K, inlet C6H6/palladium mol ratio of 35 h⁻¹). Activation of both catalysts delivered similar palladium crystallite size distributions with an average palladium diameter of 5–6 nm where the ytterbium component (in Yb–Pd/SiO2) was present as a thin surface coating. The Pd–Yb bimetallic exhibited significantly higher HDC and hydrogenation activities, the former manifested by significantly greater fractional dechlorinations and benzene selectivities/yields. Yb/SiO2 proved inactive in terms of promoting hydrogen scission or addition and the promotional effect of ytterbium in Yb–Pd/SiO2 is discussed in terms of electron donation and hydrogen transfer via surface YbH2. Under identical reaction conditions, a lower HDC activity was recorded for 1,2-DCB compared with CB, a response that is attributed to steric constraints allied to the deactivating effect of the second chlorine substituent. Both Pd/SiO2 and Yb–Pd/SiO2 exhibited a decline in HDC activity with time-on-stream, but the bimetallic was significantly more resistant to deactivation. Copyright © 2003 John Wiley & Sons, Ltd.

In coordinating solvents such as CH3CN, pyridine, and DMF, solvent separated ion pairs result when the transition metal centers and the bidentate ligands of the transition metal anions are not sufficiently nucleophilic to coordinate to lanthanide ions. With highly nucleophilic transition metal carbonylates, direct transition metal-lanthanide bonds as well as lanthanide-isocarbonyl linkages are possible. Direct bonds between ytterbium and iron are present in [(CH3CN)3YbFe(CO)4]2·CH3CN∞a one-dimensional ladder, and (CH3CN)3YbFe(CO)4∞, a two dimensional sheet. The ladder polymers (DMF)4EuNi(CN)[in4]∞and (DMF)4EuPt(CN)4∞, are formed2−in DMF. In these complexes the Eu(II) and transition metals are bridged by the cyanide ions, and no direct lanthanide-transition metal bonds are present. Two types of one-dimensional polymers of general formula (DMF)10Ln2[M(CN)4]3∞that contain a cyanide bridge between the lanthanide(III) and the transition metal(II) have been prepared. Type A: Ln = Yb, Er, Sm; M = Ni. Type B: Ln = Yb, M = Pt; Ln = Eu, M = Ni. Both types of complex contain the same repeating unit. But the type A complex contains diamond shaped Ln2M2cores linked together in an infinite array by M(CN)42−anions generating a single strand chain, while the type B complex contains two parallel zigzag chains that are inverted with respect to each other and are linked by M(CN)42−ions. By blocking one of the available trivalent lanthanide coordination sites with a chloride ion, the commonly observed zigzag chain structure of the tetracyanometallates(II) is adopted by (DMF)5Sm[Ni(CN)4]Cl∞and (DMA)4YbNi(CN)4Cl∞

DADB synthesis: The diammoniate of diborane (DADB) was synthesized in a new metathesis reaction between the diammoniate of monochloroborane and potassium borohydride in liquid ammonia (see scheme). 1H and 11B NMR spectra of DADB are reported. The stability in THF was examined by variable‐temperature 11B NMR spectroscopy.

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The title compound is prepared by a metathesis reaction between unsolvated NaB3H8and NH4Cl in liquid ammonia at ‐78 °C (30 min, 95% yield).

Unsolvated NaB3H8is prepared by reaction of Na/Hg amalgam with THF·BH3at room temperature for 3 d (<70% yield).

ChemInform is a weekly Abstracting Service, delivering concise information at a glance that was extracted from about 100 leading journals. To access a ChemInform Abstract of an article which was published elsewhere, please select a “Full Text” option. The original article is trackable via the “References” option.

ChemInform is a weekly Abstracting Service, delivering concise information at a glance that was extracted from about 200 leading journals. To access a ChemInform Abstract, please click on HTML or PDF.

ChemInform is a weekly Abstracting Service, delivering concise information at a glance that was extracted from about 200 leading journals. To access a ChemInform Abstract, please click on HTML or PDF.

ChemInform is a weekly Abstracting Service, delivering concise information at a glance that was extracted from about 200 leading journals. To access a ChemInform Abstract, please click on HTML or PDF.

For Abstract see ChemInform Abstract in Full Text.

For Abstract see ChemInform Abstract in Full Text.

ChemInform is a weekly Abstracting Service, delivering concise information at a glance that was extracted from about 100 leading journals. To access a ChemInform Abstract of an article which was published elsewhere, please select a “Full Text” option. The original article is trackable via the “References” option.