Pentasubstituted Ferrocene and Dirhodium(II) Tetracarboxylate as Building Blocks for Discrete Fullerene-Like and Extended Supramolecular Structures

Abstract

The synthesis of a penta(1-methylpyrazole)ferrocenyl phosphine oxide ligand (1) [Fe(C(5)(C(3)H(2)N(2)CH(3))(5))(C(5)H(4)PO(t-C(4)H(9))(2))] is reported together with its X-ray crystal structure. Its self-assembly behavior with a dirhodium(II) tetraoctanoate linker (2) [Rh(2)(O(2)CC(7)H(15))(4)] was investigated for construction of fullerene-like assemblies of composition [(ligand)(12)(linker)(30)]. Reaction between 1 and 2 in acetonitrile resulted in the formation of a light purple precipitate (3). Evidence for the ligand-to-linker ratio of 1:2.5 expected for a fullerene-like structure [Fe(C(5)(C(3)H(2)N(2)CH(3))(5))(C(5)H(4)PO(t-C(4)H(9))(2))](12)[Rh(2)(O(2)CC(7)H(15))(4)](30) was obtained from (1)H NMR and elemental analysis. IR and Raman studies confirmed the diaxially bound coordination environment of the dirhodium linker by comparing the stretching frequencies of the carboxylate group and the rhodium-rhodium bond with those in model compound (5), [Rh(2)(O(2)CC(7)H(15))(4)](C(3)H(3)N(2)CH(3))(2), the bis-adduct of linker 2 with 1-methylpyrazole. X-ray powder diffraction and molecular modeling studies provide additional support for the formation of a spherical molecule topologically identical to fullerene with a diameter of approximately 38 Å and a molecular formula of [(1)(12)(2)(30)]. Dissolution of 3 in tetrahydrofuran (THF) followed by layering with acetonitrile afforded purple crystals of [(1)(2)(2)](∞) (6) [Fe(C(5)(C(3)H(2)N(2)CH(3))(5))(C(5)H(4)PO(t-C(4)H(9))(2))][Rh(2)(O(2)CC(7)H(15))(4)](2) with a two-dimensional polymeric structure determined by X-ray crystallography. The dirhodium linkers link ferrocenyl units by coordination to the pyrazoles but only four of the five pyrazole moieties of the pentapyrazole ligand are coordinated. The ligand-to-linker ratio of 1:2 in 6 was confirmed by (1)H NMR spectroscopy and elemental analysis, while results from IR and Raman are in agreement with the diaxially coordinated environment of the linker observed in the solid state.

An Icosidodecahedral Supramolecule Based on Pentaphosphaferrocene: From a Disordered Average Structure to Individual Isomers

“…Although supramolecular chemistry is based on nature,i t has become an indispensable and fascinating field for the directed synthesis of certain assemblies.A mong these, discrete spherical supramolecules are particularly surprising as they can reach large dimensions,a pproaching the size of small proteins,a nd often provide defined inner cavities suitable for guest enclosure, [1] in addition to an unprecedented molecular symmetry and challenging solid-state chemistry, including crystallography.For their synthesis by self-assembly, non-covalent bonds in particular provide many advantages, such as the combination of strength and reversibility.A st he donor-acceptor bonding is directional, rational design becomes possible by variation of the symmetry and geometry of the corresponding building blocks. [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-P 5 ligand in [Cp R Fe(h 5 -P 5 )] (1;C p R = Cp* = h 5 -C 5 Me 5 (1a); Cp Bn = h 5 -C 5 (CH 2 Ph) 5 (1b); Cp BIG = h 5 -C 5 (4-nBuC 6 H 4 ) 5 (1c); 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.…”

Oligomeric complexes of some heteroaromatic ligands and aromatic diamines with rhodium and molybdenum tetracarboxylates: 13 C and 15 N CPMAS NMR and density functional theory studies

“…1), as well as other dimeric paddle-wheel-like molecules, attract interest of chemistry, spectroscopy, biology and related areas because of their complexation abilities. [1] These molecules enable the construction of supramolecular ensembles, such as triangles, [2] squares, [2][3][4][5] molecular wires, [6] fullerene-like structure [7] and coordination polymers. [8][9][10][11][12][13][14][15][16][17][18][19] The dimetallic cores can be linked either via equatorial substituents, by acid residues or via an axially bonded multifunctional ligand.…”

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

“…

Although supramolecular chemistry is based on nature,i t has become an indispensable and fascinating field for the directed synthesis of certain assemblies.A mong these, discrete spherical supramolecules are particularly surprising as they can reach large dimensions,a pproaching the size of small proteins,a nd often provide defined inner cavities suitable for guest enclosure, [1] in addition to an unprecedented molecular symmetry and challenging solid-state chemistry, including crystallography.For their synthesis by self-assembly, non-covalent bonds in particular provide many advantages, such as the combination of strength and reversibility.A st he donor-acceptor bonding is directional, rational design becomes possible by variation of the symmetry and geometry of the corresponding building blocks.[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-P 5 ligand in [Cp R Fe(h 5 -P 5 )] (1;C p R = Cp* = h 5 -C 5 Me 5 (1a); Cp Bn = h 5 -C 5 (CH 2 Ph) 5 (1b); Cp BIG = h 5 -C 5 (4-nBuC 6 H 4 ) 5 (1c); 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. Moreover,t he use of fivefold-symmetric building blocks distinguishes this research from other concepts developed by the groups of Fujita, [6] Stang, [7] Raymond, [8] and Nitschke, [1a, 9] which are all based on the coordination of N-and O-donor polytopic linkers to transition metals.

In combination with various Lewis acidic metal cations, substituted pentaphosphaferrocenes [Cp R Fe(h 5 -P 5 )] have enabled the discovery and investigation of al arge variety of one-and two-dimensional polymers (coordination via 2, 3, or 4Patoms of the cyclo-P 5 ligand) [10] and discrete spherical compounds (mostly from the coordination of all 5Patoms) [11] over the last decade.S elected examples are depicted in Figure 2.

…”

“…[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.…”

“…[2] Im Unterschied zu sechsfach-symmetrischen Bausteinen, die 2D-Schichten bilden, ermçglichen pentatope Knoten eine Krümmung und führen zu einzigartigen sphärischen Aggregaten. Zusätzlich zu unserem Ansatz der Verwendung des planaren fünffach-symmetrischen cyclo-P 5 -Liganden [Cp R Fe(h 5 -P 5 )] (1;C p R = Cp* = h 5 -C 5 Me 5 (1a), Cp Bn = h 5 -C 5 (CH 2 Ph) 5 (1b), Cp BIG = h 5 -C 5 (4-nBuC 6 H 4 ) 5 (1c); Abbildung 1a)v erwendeten andere Gruppen, wie Williams et al und Wright et al,e benfalls fünffach-symmetrische Ausgangsmaterialien, wie den Pentakis(4-pyridyl)cyclopentadienid-(Abbildung 1b) [3] und den Pentakis(1-methylpyrazol)cyclopentadienid-Liganden (Abbildung 1c) [4] oder auch [C 5 (CN) 5 ] À (Abbildung 1d). [5] Anders als bei 1 enthalten alle diese Liganden Stickstoff als Donoratom.…”