A Dimeric Gallium Hydrazide as an Active Lewis Pair - Complexation and Activation of Me2GaH and Various Heterocumulenes

Synthesis, characterization and in vitro cytotoxicity of gallium(III)-dithiocarbamate complexes

A library of homoleptic mononuclear Ga(III) complexes of the general formula [Ga(DTC)3], where DTC is an alicyclic or a linear dithiocarbamate chelator, is reported. The complexes were prepared in high yields starting from Ga(NO3)3·6H2O and fully characterized by elemental analysis and IR and NMR spectroscopy. Crystals of five of these complexes were obtained. The antitumor activity of the newly synthesized compounds against a panel of human cancer cell lines was evaluated. The chemical nature of the DTC does not have a marked impact on the structural features of the final compound. X-ray crystal structure analyses revealed that all these complexes have a trigonal prismatic geometry with three identical chelating DTCs coordinating the Ga(III) ion. It is noteworthy that in complex 22, [Ga(NHEt)3] (NHEt = N-ethyldithiocarbamate), the asymmetric unit is formed by two independent and structurally different molecules. Cellular studies showed that all the synthesized Ga-DTC complexes exhibit marked cytotoxic activity, even against human colon cancer cells that are less sensitive to cisplatin. Among the tested compounds, 6 ([Ga(CEPipDTC)3], CEPipDTC = (ethoxycarbonyl)-piperidinedithiocarbamate) and 21 ([Ga(Pr-13)3], PR13 = 4 and N-(2-ethoxy-2-oxoethyl)-N-methyldithiocarbamate) are very promising derivatives, but they have no selectivity towards cancer cells. Nevertheless, the obtained data provide a foundation for developing gallium-dithiocarbamate complexes as anticancer agents.

Quo Vadis CO2 Activation: Catalytic Reduction of CO2 to Methanol Using Aluminum and Gallium/Carbon-based Ambiphiles

We report on so-called "hidden FLPs" (FLP: frustrated Lewis pair) consisting of a phosphorus ylide featuring a group 13 fragment in the ortho position of a phenyl ring scaffold to form five-membered ring structures. Although the formation of the Lewis acid/base adducts was observed in the solid state, most of the title compounds readily react with carbon dioxide to provide stable insertion products. Strikingly, 0.3-3.0 mol% of the reported aluminum and gallium/carbon-based ambiphiles catalyze the reduction of CO2 to methanol with satisfactory high selectivity and yields using pinacol borane as stoichiometric reduction equivalent. Comprehensive computational studies provided valuable mechanistic insights and shed more light on activity differences.

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.

Recent Advances in the Chemistry of Metal Carbamates

Following a related review dating back to 2003, the present review discusses in detail the various synthetic, structural and reactivity aspects of metal species containing one or more carbamato ligands, representing a large family of compounds across all the periodic table. A preliminary overview is provided on the reactivity of carbon dioxide with amines, and emphasis is given to recent findings concerning applications in various fields.

Cooperative activation of azides by an Al/N-based active Lewis pair – unexpected insertion of nitrogen atoms into C–Si bonds and formation of AlCN3 heterocycles

The active Lewis pairs (ALPs) 2,6-Me2H8C5N–C(H) = C(SiMe3)–AlR2 (1a: R =  t Bu, 1b, R =  i Bu) have strained AlC2N heterocycles and relatively weak Al–N bonds. They react readily with a series of organic azides R′N3 [R′ = Ph, CH2C6H4(4- t Bu), t Bu, SiMe3, CH2Ph] by cleavage of the heterocycles and addition of the azides with their α-N atoms to the Al atom. The Al–N interactions result in an activation of the azide groups which insert into the C–Si bonds of the vinyl groups with their terminal γ-N atoms. Compounds with approximately planar five-membered AlCN3 heterocycles and intact N3 groups are formed in highly selective reactions.