Hexaaqua­gallium(III) trinitrate trihydrate

The title compound, [Ga(H2O)6](NO3)3·3H2O, is isostructural to other known M III nitrate hydrates (M = Al, Cr, Fe). The structure contains two distinct octa­hedral Ga(OH2)6 units (each of symmetry) which are involved in inter­molecular hydrogen bonding with the three nitrate anions and three water mol­ecules within the asymmetric unit

Anhydrous TEMPO-H: reactions of a good hydrogen atom donor with low-valent carbon centres

Publisher's version/PDFIn this paper, we report a novel synthesis of anhydrous 1-hydroxy-2,2,6,6-tetramethyl-piperidine (TEMPO-H). An X-ray crystal structure and full characterization of the compound are included. Compared to hydrated TEMPO-H, its anhydrous form exhibits improved stability and a differing chemical reactivity. The reactions of anhydrous TEMPO-H with a variety of low-valent carbon centres are described. For example, anhydrous TEMPO-H was reacted with 1,3-bis(2,4,6-trimethylphenyl)-imidazol-2-ylidene (IMes), an unsaturated NHC. Crystals of CHNC[subscript 6H[subscript 2](CH[subscript 3])[subscript 3]][subscript 2]C...HO-(NC[subscript 5]H[subscript 6](CH[subscript 3])[subscript 4]), IMes...TEMPO-H, were isolated and a crystal structure determined. The experimental structure is compared to the results of theoretical calculations on the hydrogen-bonded dimer. Anhydrous TEMPO-H was also reacted with the saturated NHC, 1,3-bis(2,6-diisopropylphenyl)imidazolidin-2-ylidene (SIPr), giving the product [CH[subscript 2]Ni-Pr[subscript 2]C[subscript 6]H[subscript 3]][subscript 2]CH...O(NC[subscript 5]H[subscript 6](CH[subscript 3])[subscript 4]). In contrast, the reaction of hydrated TEMPO-H with 1,3-bis(2,6-diisopropylphenyl)imidazolidin-2-ylidene gave small amounts of the hydrolysis product, N-(2,6-diisopropylphenyl)-N-[2-(2,6-diisopropylphenylamino)ethyl]formamide. Finally, anhydrous TEMPO-H was reacted with (triphenylphosphoranylidene)ketene to generate Ph[subscript 3]PC(H)C(=O)O(NC[subscript 5]H[subscript 6](CH[subscript 3])[subscript 4]). A full characterization of the product, including an X-ray crystal structure, is described

An Ab Initio Investigation of the Hydration of Lead(II)

The structure of lead(II) is not well known in aqueous solution. The Hartree–Fock and second order Møller–Plesset levels of theory using the CEP, LANL2, and SDD effective core potentials in combination with their associated basis sets, or with the 6-31G* and 6-31+G* basis sets were used to calculate the energies, structures, and vibrational frequencies of Pb2+(H2O)n, n = 0–9, 18. The lead–oxygen distances and totally symmetric stretching frequency of the aqualead(II) ions from different levels of theory were compared with each other, and with solution measurements where available. The calculations support a hemidirected hexacoordinate structure

Interpreting the Microwave Spectra of Diatomic Molecules

A brief review of the theory of the rigid rotor and its application to microwave spectroscopy is given. By careful selection of examples, procedures are given for the analysis of successively more complicated spectra, and the theory is extended to the harmonic nonrigid rotor and anharmonic nonrigid rotor when needed. The microwave spectra of carbon monoxide, and of some alkali halides, provide excellent examples for analysis and for student exercises

An Ab Initio Investigation of the Hydration of Tin(II)

The structure of tin(II) is not well known in aqueous solution. The energies, structures, and vibrational frequencies of [Sn(H2O)n,]2+ n = 0–9, 18 have been calculated at the Hartree–Fock and second order Møller–Plesset levels of theory using the CEP, LANL2, and SDD effective core potentials in combination with their associated basis sets, or with the 6-31G* and 6-31+G* basis sets. The tin–oxygen distances and totally symmetric stretching frequency of the aquatin(II) ions were compared with each other, and with solution measurements where available