Dalton Transactions

doi: 10.1039/b604112bpmid: N/A

doi: 10.1039/b604113mpmid: N/A

doi: 10.1039/b604114kpmid: N/A

Wright, L. James

doi: 10.1039/b517928apmid: 16585967

Metallabenzenes are analogues of benzene in which one of the benzene CH groups has been formally replaced by a transition metal and its ancillary ligands. This article summarises some of the important recent highlights of metallabenzene chemistry including the synthesis of the first platinabenzene, the synthesis of the first metallanaphthalene (an iridanaphthalene) and the development of new synthetic routes to metallabenzenes. The results of a number of theoretical studies that provide important insights into the nature and reactivity of metallabenzenes are discussed and in the concluding section some of the immediate goals and challenges in this field are identified.

Babai, Arash; Mudring, Anja-Verena

doi: 10.1039/b517694hpmid: 16585968

The synthesis and crystal structures of the first true homoleptic bis(trifluoromethanesulfonyl)amide complex compounds of trivalent f-elements are reported with [bmpyr][Ln(TfN)], Ln = Nd, Tb and [bmpyr][Ln(TfN)], Ln = Tm, Lu.

Weiss, Rainer; Jansen, Georg; Boese, Roland; Epple, Matthias

doi: 10.1039/b514540fpmid: 16585969

According to X-ray single-crystal structure analysis, {[Cu(en)][Cu(CN)]}[Cu(en)][Cu(CN)]·2HO contains copper in four different coordination environments: trigonal planar, square planar, square pyramidal and tetrahedral. The different coordination geometries of copper were investigated by quantum chemical calculations of model compounds, thus allowing to tentatively assign the different CN-bands in the IR spectrum. The thermolysis led to sub-µm sized rod-like copper() oxide particles.

Habata, Yoichi; Osaka, Futoshi

doi: 10.1039/b513931gpmid: 16585970

New pyridylmethyl armed-monoazadithiaoxa- and monoazatrithia-12-crown-4 have been prepared. The structures of the Ag complexes of the new ligands were investigated by X-ray crystallography, H NMR titrations, and FAB-MS measurements. In all cases, the Ag complexes form dimetallo[3.3]para- or metacyclophane structures depending on the position of the N atom of the pyridine rings.

Reis, Patrícia M.; Romão, Carlos C.; Royo, Beatriz

doi: 10.1039/b514930dpmid: 16585971

The dioxomolybdenum() complexes [MoOCl] (), [MoO(acac)] (), [MoO(SCNEt)] (), [CpMoOCl] (), [MoO(mes)] () and the polymeric organotin-oxomolybdates [(RSn)MoO] [R = -Bu (), -Bu (), Me ()] were examined as catalysts for the hydrosilylation of aldehydes and ketones with dimethylphenylsilane. Of these, [MoOCl] () was the most efficient catalyst, affording quantitative yields of the corresponding silylated ethers at room temperature in acetonitrile. Complexes , also catalyzed the same reaction but required heating at 80 °C and longer reaction times compared with . Compound is inactive. The wide scope of molybdenum oxide-mediated hydrosilylation was established with a variety of aldehydes and ketones. Counter intuitively, the activity of is highest in NCMe. In the absence of a carbonyl substrate, [MoOCl(NCBu)] () reacts with HSiMePh affording [MoO(OSiMePh)Cl] () which has been fully characterized by NMR and IR spectroscopy, elemental analyses and mass spectrometry. Addition of radical scavengers strongly slows down the [MoOCl]-based hydrosilylation suggesting the intermediacy of oxygen-centered radicals.

Gehrhus, Barbara; Hitchcock, Peter B.; Pongtavornpinyo, Ruti; Zhang, Lihong

doi: 10.1039/b514666fpmid: 16585972

Reduction of ClSi[(NR)CH-1,2] (R = CHBu) with potassium is known to lead to the stable silylene Si[(NR)CH-1,2] (). However, silylene is now shown to react further with an alkali metal (Na or K) to yield the (), -()˙, -() or -() derivatives. Reduction of ClSi[(NR)CH-1,2] (R = CHCH or CHCHMe) with potassium does not lead to an isolable silylene, but such a silylene is proposed to be an intermediate and, as for , reacts further to afford the potassium salts of -[Si{(NR)CH-1,2}]˙ and -[Si{(NR)CH-1,2}]. The pathways leading to the anionic cyclotri- and cyclotetrasilanes are discussed and supported experimentally; including by X-ray structures of relevant intermediates.

Sipos, Pál; Schibeci, Mark; Peintler, Gábor; May, Peter M.; Hefter, Glenn

doi: 10.1039/b513357bpmid: 16585973

A detailed electrochemical investigation using H/Pt electrode potentiometry as well as Raman and NMR spectroscopy was carried out to develop a comprehensive chemical explanation for the unusual patterns of hydroxide concentrations observed in strongly alkaline, highly concentrated aluminate solutions (Bayer-liquors). For this, aluminate solutions with various alkaline metal background cations were investigated. The effect of the temperature on the observed patterns was also studied, and for comparison with solutions of similar concentrations, the chemical speciation of borate solutions was also studied. The formation of the NaOH ion-pair has been proven with the formation constant (defined in terms of activities) = 0.78 ± 0.08. The formation of analogous KOH or CsOH ion-pairs under the experimental conditions applied is negligible. Assuming the formation of the NaAl(OH) ion-pair is not necessary for modeling the experimental findings, as its formation causes only secondary effects on the potentiometric patterns. It has also been shown that all experimental data can be interpreted quantitatively if the formation of the doubly charged dimeric aluminate species is included in the calculation of the changes in the mean activity coefficients. The formation constant of the aluminate dimer could not be estimated purely from the H/Pt potentiometric data but a lower limit for its formation constant (defined in terms of activities) has been derived. These conclusions are in full congruency with those derived from the Raman spectra of solutions with similar concentrations, so the two independent experimental methods lead to the same set of chemical species in highly concentrated alkaline aluminate solutions.