A Synthetic, Structural, Spectroscopic, and Computational Study of Alkali Metal–Thioether, −Selenoether, and −Telluroether Interactions

Abstract

The rigid thioether-and selenoether-containing pro-ligands, 4,5-bis(phenylsulfido)-2,7,9,9-tetramethylacridan (H[AS 2 Ph2 ] (1)) and 4,5-bis(phenylselenido)-2,7,9,9-tetramethylacridan (H[ASe 2 Ph2 ] (2)), were deprotonated with one equiv of n BuLi to afford dimeric lithium complexes [Li(AE 2 Ph2 )] 2 (E = S (3), Se (4)) or with one equiv of KCH 2 Ph to afford the previously reported potassium complexes [K(AS 2 Ph2 )(dme)] x (5) and [K(ASe 2 Ph2 )(dme) 2 ] (6). Attempts to prepare a direct telluroether analogue of compounds 1−2 were unsuccessful. However, the bulky selenoether-and telluroether-containing pro-ligands 4,5bis(2,4,6-triisopropylphenylselenido)-2,7,9,9-tetramethylacridan (H[ASe 2 Tripp2 ] (7)) and 4,5-bis(2,4,6-triisopropylphenyltellurido)-2,7,9,9-tetramethylacridan (H[ATe 2 Tripp2] (8)) were accessed via the reaction of 4,5-dibromo-2,7,9,9-tetramethylacridan with three equiv of n BuLi, followed by the addition of two equiv of the corresponding diaryl dichalcogenide and quenching with dilute HCl (aq) . The new selenoether-and telluroether-containing pro-ligands were subsequently deprotonated using KCH 2 Ph to afford [K(AE 2 Tripp2 )(dme) 2 ] (E = Se (9), Te (10)). Compounds 1−10 were characterized by 1 H, 13 C{ 1 H}, 77 Se{ 1 H}, 125 Te{ 1 H}, and 7 Li NMR spectroscopy, where applicable, and single-crystal X-ray structures were obtained for all lithium and potassium complexes (3− 6 and 9−10). DFT calculations were also performed to assess the nature of bonding between the hard group 1 cations and the soft chalcogenoethers.