Aggregation of Aza Crown Ethers by Metalation: Synthesis and Crystal Structure of 1‐Lithio‐1,7‐diaza[12]crown‐4—The First Lithiated Crown Ether

Deprotonation of diaza[12]crown-4 with nBuLi results in dimerization. This is shown by the X-ray structure analysis, according to which the product obtained is 1. Each Li ion is five-coordinate and lies appreciably (ca. 0.94 Å) outside the plane of the crown ether. The experimentally found structural changes agree with those found for a model system by MNDO calculation. The Li ions in 1 are well saturated electronically but still accessible to reagents.