for H-NMR when subjected to an external magnetic field. This can be explained by the cylindrical \(pi\) cloud around the carbon-carbon triple bond. Long range coupling is also observed in the alkynes. Infrared spectroscopy is a useful complement to NMR data, and displays characteristic peaks for terminal and internal alkynes. NMR Absorptions of Alkyne Hydrogens As discussed before, a carbon-carbon triple bond is the functional characteristic of the alkynes, and protons, or hydrogens, bound to these sp-hybridized carbon atoms resonate at ? = 1.7-3.1 ppm. For example, in the NMR spectrum of 3,3-dimethyl-1-butyne, the terminal hydrogen of the alkyne appears at ? = 2.06 ppm. 3,3-dimethyl-1-butyne. The H-NMR spectrum of 3,3-dimethyl-1-butyne shows a high field signal due to the alkynyl hydrogen on the terminal alkyne. This high field position suggests a relatively shielded hydrogen, which can be explained by the cylindrical electron cloud around the axis of the molecule. When the two ? bonds are subjected to an external magnetic field, these ?

In this review, we present an overview of hydrostannation of alkynes until the end of 2018. Mechanism of the tin hydride addition on a triple bond is discussed at the beginning of this review in the presence of metal catalysts as Pd, Ru-based complexes, Lewis acids and under radical conditions. Then, stereoselectivity as well as regioselectivity aspects of tin hydride addition on the carbon triple bond is discussed using metal-catalysis, radical conditions or Lewis acids. In each of these items, the reactions will be studied for terminal alkynes and then, for internal alkynes. Applications of hydrostannation of alkynes using metal-catalysis is presented in a variety of total syntheses with Pd, Mo, Rh and Ru-complexes to provide highly functionalized vinyl stannanes derivatives as key-intermediates. Comparison with other methods providing vinyl stannanes using metallostannation followed by protonation is presented before the last section dealing with a summary of classical experimental conditions used to achieve the hydrostannation of alkynes.

Organometallic cerium(iv) complexes have been challenging to isolate and characterize due to the strongly oxidizing nature of the cerium(iv) cation. Herein, we report two cerium(iv) alkynyl complexes, [Ce(TriNOx)(C[triple bond, length as m-dash]C-SiMe3)] (1-CeTMS) and [Ce(TriNOx)(C[triple bond, length as m-dash]C-Ph)] (1-CePh) (TriNOx3- = tris(2-tert-butylhydroxylaminato)benzylamine), that include terminal alkyne moieties. The isostructural thorium analogue [Th(TriNOx)(C[triple bond, length as m-dash]C-SiMe3)] (1-ThTMS) was also synthesized and compared with 1-CeTMS in bond distance, 13C-NMR spectra, vibrational spectra and electronic structure. The Ce-C bond distances were 2.501(3) Å for 1-CePh and 2.513(5) Å for 1-CeTMS on the shorter end of the few reported CeIV-C single bonds (2.478(3)-2.705(2) Å), possibly indicating significant Ce 5d- and 4f-orbital involvement. 13C-NMR spectroscopy was also consistent with Ce-C covalency, with significantly deshielded resonances ranging from 185-213 ppm. Such 13C-NMR shifts demonstrate a strong influence from spin-orbit coupling (SOC) effects, corroborated by computational studies. Raman analysis showed ν C[triple bond, length as m-dash]C stretching frequencies of 2000 cm-1 (1-CeTMS) and 2052 cm-1 (1-CePh), indicating the cerium(iv)-alkynyl interaction, compared to the parent HC[triple bond, length as m-dash]CPh (IR = 2105 cm-1 and Raman = 2104 cm-1). L3-edge X-ray absorption measurements revealed a predominant Ce(iv) electronic config