Synthesis of Planar Five‐Connected Nodal Ligands

Abstract

Synthetic routes to a penta(4-pyridyl)cyclopentadienyl ligand are explored. The most successful route uses a palladium-catalysed pentapyridation of di(tert-butyl)phosphinoferrocene by using a procedure developed by Hartwig. The same method allows the synthesis of cyclopentadiene ligands substituted with 4-benzaldehydes or 4-phenylthiols. The pyridine ligands are formally five-connected nodes that may be linked by linear coordination metals to give closed spherical complexes of composition [(metal)(30)(ligand)(12)] as shown by molecular modelling. Experiment shows that the ligand complexes copper(I) and silver(I) with the expected 1:2.5 stoichiometry, and the (1)H NMR spectrum of the resulting product shows the ligands to be equivalent. NMR diffusion and light-scattering measurements support the formation of a species with a hydrodynamic radius of the order of 15 A, in agreement with the modelling studies. The resulting complex would be topologically identical to the C(60) fullerene structure.

Inorganic, Analytical and Applied Chemistry

“…3). [10] Finally, the use of chelating hydrogen bond donors for anion binding is being studied. [11] Analytical Chemistry Michal Borkovec's group focusses on colloid and surface chemistry, with a particular emphasis on water-solid interfaces, simple ions, and polyelectrolytes.…”

Ein ikosidodekaedrisches Supramolekül auf Basis von Pentaphosphaferrocen: von einer fehlgeordneten gemittelten Struktur zu einzelnen Isomeren

“…[2] In contrast to sixfoldsymmetric building blocks,w hich form 2D layers,t he use of pentatopic nodes allows for bending and leads to unique spherical aggregates.Aside from our approach based on using the planar fivefold-symmetric cyclo- Figure 1a), others, such as the Williams and Wright groups,a lso made use of such fivefold-symmetric starting materials,s uch as the pentakis(4-pyridyl)cyclopentadienide (Figure 1b) [3] and the pentakis(1-methylpyrazole)cyclopentadienide ligands (Figure 1c), [4] as well as [C 5 (CN) 5 ] À (Figure 1d), respectively. [5] In contrast to 1,a ll of these ligands contain nitrogen as the donating atom.…”

“…[11a-c] Adifferent approach might be the use of multifunctional anions instead of ahalide,which would avoid the limitations associated with uncontrollable oligomerization and at the same time allow for as caffold expansion of the supramolecule.T he anions could act as spacers between the Cu atoms that are additionally coordinated to the cyclo-P 5 units.A fter numerous preparative attempts with different anions,wenow present trifluoromethanesulfonate( CF 3 SO 3 À ,t riflate) as ac onvenient spacer that possesses flexible coordination properties and renders the resulting spheres well soluble at the same time. [12] Herein, we report on the first results of the self-assembly of pentaphosphaferrocene 1a and the bulkier derivative 1b, respectively,w ith Cu(CF 3 (4) 3 .X -ray structure analysis was performed in our laboratory as well as at the DESY PETRA III synchrotron (beamline P11), [13] revealing the atomic-resolution structure of an unprecedented spherical supramolecule with unique crystallographic symmetry and disorder. Thei norganic scaffold of supramolecule 3 is formed by 12 units of 1b with asimilar icosahedral mutual arrangement as in the 80-vertex ball [(Cp Different possibilities to occupy two thirds of the copper sites in the icosidodecahedral scaffold give rise to an umber of permutational isomers.O ne would intuitively think that the number of these isomers must be huge.Asystematic search for all possible isomers was performed by coding acomputer program for this purpose [14] starting from ah ypothetical fully occupied icosidodecahedral scaffold.…”

Assembly of the First Fullerene‐Type Metal–Organic Frameworks Using a Planar Five‐Fold Coordination Node

“…[3] However, among the multitude of ligand nodes reported, planar five-fold nodes are particularly rare. [4][5][6] The major interest in these nodes stems from the fact that pentagons cannot be tiled into a planar sheet arrangement but would have to distort into a curved and domed structure. This has lead to the formation of discrete fullerene-like metalorganic arrangements, based on the linkage of twelve (and more) pentagonal nodes into a spherical supramolecule.…”

“…This concept has recently been realized by the research groups of Scheer, utilizing the pentaphosphaferrocene ligand (A, Scheme 1), [4] and Williams, using the pentakis(4-pyridyl) cyclopentadienide ligand (B, Scheme 1). [5][6][7] Up to date this type of planar five-fold node has not been used for the formation of any network MOFs.The coordination chemistry of the pentacyanocyclopentadienide ligand (Scheme 1, 1) [8] has been almost unexplored to date. [5,9,10] However, recently we developed a simple synthesis of the starting material [Na{1}] [Eq.…”