Synthesis and characterization of a family of solvated sodium aryloxide compounds

Abstract

A family of crystallographically characterized solvated sodium alkoxides ([(solv)xNa(OR)]n) was synthesized from the reaction of sodium bis(trimethylsilyl)amide with a series of sterically varied aryl alcohols (H–OAr): 2-alkyl phenol [alkyl=methyl (oMP), iso-propyl (oPP), and tert-butyl (oBP)] or 2,6-di-alkyl phenol [alkyl=methyl (DMP), iso-propyl (DIP), and tert-butyl (DBP)]. Single crystal X-ray experiments revealed the structure of the products to be highly dependent on the ligand set employed and the solvent used (THF or py). The [(solv)xNa(OAr)]n products were identified as: [(THF)Na(μ3-oMP)]6 (1), [(THF)4Na6(μ3-oPP)4(μ4-oPP)2] (2), [(THF)Na(μ3-oBP)]4 (3)·THF, [(THF)Na(μ3-DMP)]4 (4), [(THF)2Na(μ-DIP)]2 (5), [(THF)2Na(μ-DBP)]2 (6), {[Na(μ-DPhP-ηx)]2}n (7), [(py)5Na6(μ3-oMP)4(μ4-oMP)2]2[(py)4Na6(μ3-oMP)4(μ4-oMP)2] (8), [(py)6Na4(μ3-oPP)4] (9)·py, [(py)Na(μ3-DMP)]4 (11), [(py)2Na(μ-DIP)]2 (12), [(py)4Na(DBP)] (13). Crystals could not be isolated for the Na/oBP/py (10) system but the powder was assigned the ‘[(py)Na(oBP)]4’ structure based on the available analytical data. In addition, under similar conditions, the neo-pentoxide (ONep) derivatives were isolated and characterized as [(solv)4Na6(μ3-ONep)4(μ4-ONep)2] (solv=THF, 14; py 15). A number of complex structures (monomers, squares, cubes, fused-cubes, hexagons) were observed for this family of [(solv)xNa(OAr)]n compounds. The solution behaviors of these compounds were studied using heteronuclear 23Na NMR. A comparison of these [(solv)xA(OR)]n A=Li, Na, K, Rb, Cs structural motifs is also presented.