Six-Membered Metalla-coronands. Synthesis and Crystal Packing:  Columns, Compartments, and 3D-Networks^,

Abstract

Reaction of various N-substituted diethanolamines H(2)L(3) (4) with calcium hydride and iron(III) chloride leads to the self-assembly of six-membered ferric wheels [Fe(6)X(6)(L(3))(6)] (5). Principally, all the iron coronands are isostructural; however, they differ fundamentally with respect to their crystal packing. Exemplarily, this is discussed for selected members of the space groups R, P, P2(1)/c, P2(1)/n, C2/c, and P. Depending on the nature of their sidearms, the ferric wheels create various substructures. For instance, the ferric wheels 5a-i of space group R or P are piled in parallel in cylindrical columns, which are surrounded by six parallel columns alternately dislocated by (1)/(3)c and (2)/(3)c against the central one. Pronounced van der Waals interactions give rise to compartmentation and incarceration of guest molecules as seen for 5e,g. However, in 5h strong pi-pi interactions create a three-dimensional scaffold. The most significant difference of the ferric wheels 5j-p of space groups P2(1)/c, P2(1)/n, and C2/c is that these ferric wheels are arranged in parallel in two orientations. They differ mainly only by the included angle of the two groups of parallel wheels. In the case of 5l, molecular chains are formed in the crystal due to pi-pi interactions. The ferric wheels 5q-y of space group P are packed in the crystal most simply, with all the ferric wheels piled in parallel.

Metal–Organic Coordination Networks of Ferric Wheels, their Surface-supported Supramolecular Architectures and STM/STS Imaging

“…The ligands were prepared as described previously for similar compounds by heating the corresponding bromides, diethanolamine and Na 2 CO 3 in CH 3 CN for 48 h [51]. To a suspension of calcium hydride (253 mg, 6 mmol) in anhydrous THF (75 ml), the corresponding N-substituted diethanolamine (H 2 L 2 ) (4 mmol) was added.…”

“…An interesting feature of oligonuclear assemblies is their readiness to frame compartments and 3D networks with discrete channels and pores [52 -64]. Principally, all the six-membered ferric wheels [Fe 6 Cl 6 (L 2 ) 6 ] (3) are isostructural; however, there are fundamental differences concerning their crystal packing [51]. For example, all the disk-like clusters of 3a -c (space group R3) are arranged in parallel and are piled up in cylindrical columns, with all the iron centers superimposed.…”

“…An especially remarkable example of crystal packing leading to porous frameworks is caused by 3D p Z p stacking of the naphthyl groups of the side arms of the ferric wheels 3c (Fig. 2) [51].…”

Syntheses and Properties of Metal‐Centered Mixed‐Valent [NEt4]{MnII⊂[MnII3MnIII3Cl6(L)6]} Manganese Wheels

“…Consequently, a series of ferric wheels was generated with N-substituted diethanolamines. [1,7] In this communication we report on the synthesis of metal-centered, heptanuclear, mixed-valent manganese wheels 8-10.…”

Synthesis and characterisation of Fe6 and Fe12 clusters using bicine

“…Although the DEA ligand has not been reported as a ligand for Fe(III) complexes, replacing the NH group by an NR (R = Me, Et etc.,) group leads to some interesting polynuclear Fe(III) complexes, including Fe 6 wheels (e.g. R = Me [8], n Bu [9]) and in the presence of carboxylate co-ligands Fe 7 or Fe 22…”