Structural diversity in solvated lithium aryloxides. Syntheses, characterization, and structures of [Li(OAr)(THF)(x)](n) and [Li(OAr)(py)(x)](2) complexes where OAr=OC6H5, OC6H4(2-Me), OC6H3(2,6-(Me))(2), OC6H4(2-Pr-i), OC6H3(2,6-(Pr-i))(2), OC6H4(2-Bu-t), OC6H3(2,6-(Bu-t))(2)

A series of sterically varied aryl alcohols H-OAr [OAr = OC6H5 (OPh), OC6H4 (2-Me) (oMP), OC6H3(2,6-(Me))(2) (DMP), OC6H4(2-Pr-i) (oPP), OC6H3(2,6-(Pr- i))(2) (DIP), OC6H4(2-Bu-t) (oBP), OC6H3(2,6-(Bu-t))(2) (DBP); Me = CH3, Pr -i = CHMe2, and Bu-t = CMe3] were reacted with LiN(SiMe3)(2) in a Lewis bas ic solvent [tetrahydrofuran (THF) or pyridine (py)] to generate the appropr iate "Li(OAr)(solv)(x)". In the presence of THF, the OPh derivative was pre viously identified as the hexagonal prismatic complex [Li(OPh)(THF)](6); ho wever, the structure isolated from the above route proved to be the tetranu clear species [Li(OPh)(THF)](4) (1). The other "Li(OAr)(THF)(x)" products i solated were characterized by single-crystal X-ray diffraction as [Li(OAr)( THF)](4) [OAr = oMP (2), DMP (3), oPP (4)1, [Li(DIP)(THF)](3) (5), [Li(oBP) (THF)(2)](2), (6), and [Li(DBP)(THF)](2), (7). The tetranuclear species (1- 4) consist of symmetric cubes of alternating tetrahedral Li and pyramidal O atoms, with terminal THF solvent molecules bound to each metal center. The trinuclear species 5 consists of a six-membered ring of alternating trigon al planar Li and bridging O atoms, with one THF solvent molecule bound to e ach metal center. Compound 6 possesses two Li atoms that adopt tetrahedral geometries involving two bridging oBP and two terminal THF ligands. The str ucture of 7 was identical to the previously reported [Li(DBP)(THF)](2) spec ies, but different unit cell parameters were observed. Compound 7 varies fr om 6 in that only one solvent molecule is bound to each Li metal center of 7 because of the steric bulk of the DBP ligand. In contrast to the structur ally diverse THF adducts, when py was used as the solvent, the appropriate "Li(OAr)(py)(x)" complexes were isolated as [Li(OAr)(py)(2)](2) (OAr = OPh (8), oMP (9), DMP (10), oPP (11), DIP (12), oBP (13)) and [Li-(DBP)(py)](2) (14). Compounds 8-13 adopt a dinuclear, edge-shared tetrahedral complex. F or 14, because of the steric crowding of the DBP ligand, only one py is coo rdinated, yielding a dinuclear fused trigonal planar arrangement. Two addit ional structure types were also characterized for the DIP ligand: [Li(DIP)( H-DIP)(py)](2) (12b) and [Li-2(DIP)(2)(py)(3)] (12c). Multinuclear (Li-6,Li -7 and C-13) solid-state MAS NMR spectroscopic studies indicate that the bu lk powder possesses several Li environments for "transitional ligands" of t he THF complexes; however, the py adducts possess only one Li environment, which is consistent with the solid-state structures. Solution NMR studies i ndicate that "transitional" compounds of the THF precursors display multipl e species in solution whereas the py adducts display only one lithium envir onment.