Structurally diverse organoamides and organoamido-, organometallic-lithiumaggregates from reactions of N-(2-phenoxyphenyl)-N-(trimethylsilyl)amine with LiBun

Deprotonation of N-(2-phenoxyphenyl)-N-(trimethylsilyl)amine ((LH)-H-1) wit h a slight excess of LiBun in tetrahydrofuran (thf) or 1,2-dimethoxyethane (dme) yielded the solvated lithium organoamide complexes (Li(L-t)(thf)](n) (1) and [Li(L-1)(dme)] (2) (L-1 = N(C6H4OPh-2)(SiMe3)), respectively. React ion of (LH)-H-1 with LiBun in hexane gave the solvent free lithium organoam ide [Li(L-1)](n) (3). Monomeric 2 was shown to have a four-coordinate lithi um centre surrounded by chelating L-1 and dme ligands in a distorted tetrah edral environment. Utilisation of diethyl ether as the reaction solvent. fo llowed by work up in hexane containing a trace of bis(2-methoxyethyl) ether (diglyme), gave a low yield of colourless crystals, shown by X-ray crystal lography to be [{Li(OEt2)(L-1)Li-2(L-11)}(2)(mu-eta (3)-O,O"-diglyme)] (4) (L-11 = N(C6H4(OC6H4-2')-2)(SiMe3)), a hexalithium cluster having both sing ly deprotonated (L-1) and doubly deprotonated (L-11) ligands. In L-11, the proton of the phenyl substituent ortho to the oxygen has been removed in ad dition to the amine hydrogen. Deliberate attempts to prepare a pure double lithiated product by reaction of (LH)-H-1 with 2 equivalents of LiBun in di ethyl ether yielded two different Li-2(L-11) complexes depending upon the c rystallisation solvent. From hexane, a hexalithium aggregate [Li-2(L-11)(OE t2)Li(Bu-n)](2) (5) was obtained. The structure of 5 showed the presence of two doubly deprotonated Li-2(L-11) units but, surprisingly, also incorpora tion of two molecules of LiBun. Alternatively. a Li-2(L-11) complex free of LiBun, [Li-2(L-11)(dme)](2) (6) was obtained by crystallisation of the pro duct. prepared in diethyl ether, from a hexane/dme mixture. Variable temper ature solution NMR (H-1, Li-7) data for 4- 6 indicated the occurrence of dy namic exchange processes at room temperature. but 4 and 5 have the same num ber of lithium environments at -90 degreesC as in the solid state structure s.