Lithiation of tris(alkyl- and arylamido)orthophosphates EP[N(H)R]3 (E=O, S, Se):: Imido substituent effects and P=E bond cleavage

In the solid state, OP[N(H)Me](3) (1a) and OP[N(H)Bu-t](3) (1b) have hydrogen-bonded structures that exhibit three-dimensional and one-dimensional arrays, respectively. The lithiation of 1b with 1 equiv of (BuLi)-Bu-n generates the trimeric monolithiated complex (THF){LiOP((NBu)-Bu-t)[N(H)Bu-t](2)}(3) (4), whereas reaction with an excess of (BuLi)-Bu-n produces the dimeric dilithium complex {(THF)(2)Li2OP((NBu)-Bu-t)(2)[N(H)Bu-t]}(2) (5). Complex 4 contains a Li2O2 ring in an open-ladder structure, whereas 5 embraces a central Li2O2 ring in a closed-ladder arrangement. Investigations of the lithiation of tris(alkyl or arylamido)thiophosphates, SP[N(H)R](3) (2a, R = Pr-i; 2b, R = Bu-t; 2c, R = p-tol) with (BuLi)-Bu-n reveal interesting imido substituent effects. For the alkyl derivatives, only mono- or dilithiation is observed. In the case of R = tBu, lithiation is accompanied by P-S bond cleavage to give the dilithiated cyclodiphosph(V/V)azane {(THF)(2)Li-2[((BuN)-Bu-t)(2)P(mu-(NBu)-Bu-t)(2)P((NBu)-Bu-t)(2)]} (9). Trilithiation occurs for the triaryl derivatives EP[N(H)Ar]3 (E = S, Ar = p-tolyl; E = Se, Ar = Ph), as demonstrated by the preparation of {(THF)(4)Li-3[SP(Np-tol)(3)]}(2) (10) and {(THF)(4)Li-3[SeP(NPh)(3)]}(2) (11), which are accompanied by the formation of small amounts of 10(.)[LiOH(THF)](2) and 11(.)Li(2)Se(2)(THF)(2), respectively.