In this work, a rare monomeric organolithium complex was reported, stabilised by a neutral tetradentate amine ligand. Its structure and decomposition/reactivity were studied.

Organosodium chemistry is underdeveloped compared with organolithium chemistry, and all the reported organosodium complexes exhibit similar, if not identical, reactivity patterns to their lithium counterparts. Herein, we report a rare organosodium monomeric complex, namely, [Na(CH 2 SiMe 3 )(Me 6 Tren)] (1-Na) (Me 6 Tren: tris[2-(dimethylamino)ethyl]amine) stabilized by a tetra-dentate neutral amine ligand Me 6 Tren. Employing organo-carbonyl substrates (ketones, aldehydes, amides, ester), we demonstrated that 1-Na features distinct reactivity patterns compared with its lithium counterpart, [Li(CH 2 SiMe 3 )(Me 6 Tren)] (1-Li). Based on this knowledge, we further developed a ligand-catalysis strategy to conduct ketone/aldehyde methylenations, using [NaCH 2 SiMe 3 ] ∞ as the CH 2 feedstock, replacing the widely used but hazardous/expensive C�O methylenation methods, such as Wittig, Tebbe, Julia/Julia-Kocienśki, Peterson, and so on.

The reaction between the phosphine-borane-stabilised dicarbanion complex [1,2-C6H4{CHP(BH3)Cy2}2][Li(THF)n]2 and Cp2Sn gives the unusual stannyl-stannylene [[1,2-C6H4{CHP(BH3)Cy2}2]Sn]2·1½PhMe, in which one dicarbanion ligand chelates a tin centre, while the other bridges a tin-tin bond. The stannylene centre is stabilised by an agostic-type B-H···Sn interaction.

This work comprehensively investigated the coordination chemistry of a hexa -dentate neutral amine ligand, namely, N,N′,N” - tris -(2- N -diethylaminoethyl)-1,4,7-triaza-cyclononane (DETAN), with group-1 metal cations (Li + , Na + , K + , Rb + , Cs + ). Versatile coordination modes were observed, from four-coordinate trigonal pyramidal to six-coordinate trigonal prismatic, depending on the metal ionic radii and metal’s substituent. For comparison, the coordination chemistry of a tetra -dentate tris -[2-(dimethylamino)ethyl]amine (Me 6 Tren) ligand was also studied. This work defines the available coordination modes of two multidentate amine ligands (DETAN and Me 6 Tren), guiding future applications of these ligands for pursuing highly reactive and elusive s-block and rare-earth metal complexes.