[PHLINCH2CH2NLIPH].3HMPA, A MONOMERIC DILITHIUMETHYLENEDIAMIDE COMPLEX WITH N2LI2 DOUBLE BRIDGING - SYNTHESIS, CRYSTAL-STRUCTURE, AND MODEL MO CALCULATIONS

An Li2N2O bicyclo[1.1.1]pentane‐type structure is characteristic of the trilithiated N,N'‐diphenylethylenediamine in the presence of hexamethylphosphortriamide (HMPA). Li⊕ ions bridge the two N⊖ centers in this “ion triplet” in an‐asymmetric fashion. Each of the Li⊕ ions is also coordinated to a terminal HMPA ligand (only the O atom of which is shown in the illustration to the right) and further bridged by a third HMPA ligand. The structural principles underlying this complex were predicted by ab initio calculations, and they can be rationalized in terms of a simple electrostatic model. (Figure Presented.) Copyright © 1990 by VCH Verlagsgesellschaft mbH, Germany