A Synthetic, Structural, Spectroscopic, and Computational Study of Alkali Metal-Thioether, -Selenoether, and -Telluroether Interactions.

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 4,5-bis(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.