Citation:
Abstract:
The reaction of Cl3PNSiMe3 with 3 equiv of LiHNR (R = Pr-i, Cy, Bu-t, Ad) in diethyl ether produces the corresponding tris(amino)(imino)phosphoranes (RNH)(3)PNSiMe3 (1a, R = Pr-i; 1b, R = Cy; 1c, R = Bu-t; 1d, R = Ad); subsequent reactions of 1b-d with (BuLi)-Bu-n yield the trilithiated tetraimidophosphates {Li-3[P(NR)(3)(NSiMe3)]} (2a, R = Cy; 2b, R = Bu-t; 2c, R = Ad). The reaction of [((BuNH)-Bu-t)(4)P]Cl With 1 equiv of (BuLi)-Bu-n results in the isolation of ((BuNH)-Bu-t)(3)(PNBu)-Bu-t (1e); treatment of le with additional nBuLi generates the symmetrical tetraimidophosphate {Li-3[P(NtBu)(4)]} (2d). Compounds 1 and 2 have been characterized by multinuclear (H-1, C-13, and P-31) NMR spectroscopy; X-ray structures of 1b,c were also obtained. Oxidations of 2a-c with iodine, bromine, or sulfuryl chloride produces transient radicals in the case of 2a or stable radicals of the formula {Li-2[P(NR)(3)(NSiMe3)]LiX center dot 3THF}(center dot) (X = Cl, Br, I; R = Bu-t, Ad). The stable radicals exhibit C3 symmetry and are thought to exist in a cubic arrangement, with the monomeric LiX unit bonded to the neutral radical {Li-2[P(NR)(3)(NSiMe3)]}(center dot) to complete the Li3N3PX cube. Reactions of solvent-separated ion pair {[Li(THF)(4)]{Li(THF)(2)[(mu-(NBu)-Bu-t)(2)P(mu-(NBu)-Bu-t)(2)]Li(THF)(2)} (6) with I-2 or SO2Cl2 produce the persistent spirocyclic radical {(THF)(2)Li mu-(NBu)-Bu-t)(2)P(mu-(NBu)-Bu-t)Li(THF)(2)}(center dot) (10a); all radicals have been characterized by a combination of variable concentration EPR experiments and DFT calculations.
Notes:
Times Cited: 11Armstrong, AF Chivers, T Tuononen, HM Parvez, M Boere, RT