m-Terphenylaluminum and -gallium Compounds: Synthesis and Conversion into Low-Coordinate Organogallium Cations

Adamantane-type clusters: compounds with a ubiquitous architecture but a wide variety of compositions and unexpected materials properties

The research into adamantane-type compounds has gained momentum in recent years, yielding remarkable new applications for this class of materials. In particular, organic adamantane derivatives (AdR4) or inorganic adamantane-type compounds of the general formula [(RT)4E6] (R: organic substituent; T: group 14 atom C, Si, Ge, Sn; E: chalcogenide atom S, Se, Te, or CH2) were shown to exhibit strong nonlinear optical (NLO) properties, either second-harmonic generation (SHG) or an unprecedented type of highly-directed white-light generation (WLG) - depending on their respective crystalline or amorphous nature. The (missing) crystallinity, as well as the maximum wavelengths of the optical transitions, are controlled by the clusters' elemental composition and by the nature of the organic groups R. Very recently, it has been additionally shown that cluster cores with increased inhomogeneity, like the one in compounds [RSi{CH2Sn(E)R'}3], not only affect the chemical properties, such as increased robustness and reversible melting behaviour, but that such 'cluster glasses' form a conceptually new basis for their use in light conversion devices. These findings are likely only the tip of the iceberg, as beside elemental combinations including group 14 and group 16 elements, many more adamantane-type clusters (on the one hand) and related architectures representing extensions of adamantane-type clusters (on the other hand) are known, but have not yet been addressed in terms of their opto-electronic properties. In this review, we therefore present a survey of all known classes of adanmantane-type compounds and their respective synthetic access as well as their optical properties, if reported.

Handling considerations for the mass spectrometry of reactive organometallic compounds

Mass spectrometry is a powerful tool in disparate areas of chemistry, but its characteristic strength of sensitivity can be an Achilles heel when studying highly reactive organometallic compounds. A quantity of material suitable for mass spectrometric analysis often represents a tiny grain or a very dilute solution, and both are highly susceptible to decomposition due to ambient oxygen or moisture. This complexity can be frustrating to chemists and analysts alike: the former being unable to get spectra free of decomposition products and the latter often being poorly equipped to handle reactive samples. Fortunately, many creative solutions to such problems have been developed. This review summarizes some key methods for handling reactive samples in conjunction with the various ionization methods most frequently employed for their analysis.

Molecular Main Group Metal Hydrides

This review serves to document advances in the synthesis, versatile bonding, and reactivity of molecular main group metal hydrides within Groups 1, 2, and 12-16. Particular attention will be given to the emerging use of said hydrides in the rapidly expanding field of Main Group element-mediated catalysis. While this review is comprehensive in nature, focus will be given to research appearing in the open literature since 2001.

Cationic aluminum, gallium, and indium complexes in catalysis

The introduction of cationic charge allows cationic group 13 complexes to be excellent Lewis acid catalysts. Cationic aluminum, gallium, and indium complexes in catalysis are comprehensively reviewed based on the reaction type.

Oxygen-Bridged Ga2 (Et)3 (OTeF5 )3 and the Weakly Coordinating Anions [Ga(Et)(OTeF5 )3 ]- and [Ga(OTeF5 )4 ]. Chemistry 2019;25:10441-10449. [PMID: 31090983 DOI: 10.1002/chem.201901651]

Salts of the weakly coordinating anions [Ga(OTeF₅ )₄ ]^- as well as [Ga(Et)(OTeF₅ )₃ ]^- and the neutral Ga₂ (Et)₃ (OTeF₅ )₃ were synthesized and characterized by spectroscopic methods and single-crystal X-ray diffraction. Ga₂ (Et)₃ (OTeF₅ )₃ was formed by treating GaEt₃ with pentafluoroorthotelluric acid (HOTeF₅ ) and reacted with PPh₄ Cl and CPh₃ Cl to [PPh₄ ][Ga(Et)(OTeF₅ )₃ ] and [CPh₃ ][Ga(Et)(OTeF₅ )₃ ]. In contrast, Ag[Ga(OTeF₅ )₄ ] was prepared from AgOTeF₅ and GaCl₃ and was used as a versatile starting material for further reactions. Starting with Ag[Ga(OTeF₅ )₄ ] the substrates [PPh₄ ][Ga(OTeF₅ )₄ ] and [CPh₃ ][Ga(OTeF₅ )₄ ] were formed from PPh₄ Cl and CPh₃ Cl.

Alkylaluminum, -gallium, -magnesium, and -zinc monophenolates with bulky substituents

The bulky phenols 2,6-Ad2C6H3OH (Ad=adamantyl), A, (2,6-Ph2CH)2-4-Me-C6H2OH, B, and (2,6-Tol2CH)2-4-iPr-C6H2OH, C, react with one equivalent of Et3M (M=Al, Ga), Bu2Mg and Et2Zn to afford well-defined mono-phenolate complexes (ArOMRn)m. The aluminum and gallium phenolates derived from the very bulky phenol A are likely monomeric in the solid state. The other compounds are dimeric with bridging phenolates. Crystal structures of compounds with phenols B and C display the dimeric M2O2 cores of the phenolates and illustrate some deviations for the magnesium and zinc compounds. The former possesses stabilizing Mg···C contacts with one of the flanking arene groups of the phenolate substituent, and the latter may be viewed as an intermediate between a symmetric dimer and two monomers. All compounds were characterized by 1H and 13C NMR spectroscopy, and their solution spectra are in agreement with the crystal structure data.

Reversible 1,1-hydroaluminations and C–H activation in reactions of a cyclic (alkyl)(amino) carbene with alane

Varying the reaction ratio of cyclic (alkyl)(amino) carbene (cAAC^Et) with AlH₃·NEtMe₂ leads to the isolation of (cAAC^EtH)AlH₂·NEtMe₂1 and (cAAC^EtH)₂Al(μ-H)₂AlH₂·NEtMe₂2 and the first example of a monomeric dialkyl-aluminum hydride (cAAC^EtH)₂AlH 3.

Structural analysis of organometallic compounds with soft ionization mass spectrometry

The analysis of organometallic compounds with mass spectrometry has some special features in comparison with organic and bioorganic compounds. The first step is the choice of a suitable ionization technique, where the electrospray ionization is certainly the best possibility for most classes of organometallic compounds and metal complexes. Some ionization mechanisms of organometallic compounds are comparable to organic molecules, such as protonation/deprotonation, and adduct formation with sodium or potassium ions; however, in many cases, different mechanisms and their combinations complicate the spectra interpretation. Organometallics frequently undergo various types of adduct and polymerization reactions that result in significantly higher masses observed in the spectra in comparison to molecular weights of studied compounds. Metal elements typically have more natural isotopes than common organic elements, which cause characteristic wide distributions of isotopic peaks; for example, tin has ten natural isotopes. The isotopic pattern can be used for the identification of the type and number of metal elements in particular ions. The ionization and fragmentation behavior also depend on the type of metal atom; therefore, our discussion of mass spectra interpretation is divided according to the different type of organometallic compounds. Among various types of mass spectrometers available on the market, trap-based analyzers (linear or spherical ion-traps, Orbitrap) are suitable to study complex fragmentation pathways of organometallic ions and their adducts, whereas high-resolution and high-mass accuracy analyzers (time-of-flight-based analyzers, or Fourier transform-based analyzers-Orbitrap or ion cyclotron resonance mass spectrometers) provide accurate masses applicable for the determination of the elemental composition of individual ions.