Metal-Deficient Supramolecule Based on a Fivefold-Symmetric Building Block

Pseudohalide Ions as Ligands to Tune Architecture and Luminescence of Polymetallic CU(I) Assemblies

The reaction of preassembled Cu(I) bimetallic units {Cu2(dppm)2} and {Cu2(dppa)2} (dppm: bis(diphenylphosphino)methane and dppa: bis(diphenylphosphino)amine) with pseudohalide linkers (azido, dicyanamide, and tricyanomethanide) allows for the quantitative and selective preparation of three discrete tetrametallic metallacycles of formula [Cu4(μ2-dppm)4(N3)2](PF6)2, [Cu4(μ2-dppm)4(N(CN)2)2](PF6)2, and [Cu4(μ2-dppm)4(C(CN)3)4]. To explore further the impact of the linker on the architecture and dimensionality of the molecular edifice, the study was extended to more sophisticated tetradentate cyanocarbanion ligands (tcnsMe-: 2-(methylthio)-1,1,3,3-propanetetracarbonitrile and tcnsEt-: 2-(ethylthio)-1,1,3,3-propanetetracarbonitrile). Three ladder-like one-dimensional coordination polymers and an octametallic metallacycle have been obtained. The careful comparison of the metric and geometrical intramolecular and intermolecular parameters observed in this series of seven derivatives allows for rationalization of their molecular architectures. The subtle balance between the length and steric hindrance of the ligand and the formation of noncovalent interaction networks greatly influences the topology and dimensionality of the resulting assemblies and will be discussed hereafter. The photophysical properties of these seven polymetallic Cu(I) compounds have also been also studied.

Cyclo-E5-bridged trinuclear triple-decker complexes (E = P, As) containing a triply-bonded Mo2 unit and their isomerisation

The reaction of the low-coordinate quadruply-bonded dimolybdenum complex Mo2[μ,κ2-PhB(N-2,6-iPr2C6H3)2]2 (1) with Cp*Fe(η5-E5) (E = P, As) gives two trinuclear species Cp*Fe(μ3,η5:2:2-E5)Mo2[μ,κ2-PhB(N-2,6-iPr2C6H3)2]2 (E = P (4) and As (5)). 4 undergoes facile isomerisation upon heating to give Cp*FeMo2[κ2-PhB(N-2,6-iPr2C6H3)2](μ3,κ:κ:η2-P2)[μ3,κ:κ:η3κ-P3PhB(N-2,6-iPr2C6H3)2] (6), where the FeMo2P5 core motif displays a cubane-like structure.

A lens-shaped supramolecule based on the bulky pentaphosphaferrocene [CpBIGFe(η5-P5)] and CuBr2

Besides inherent fullerene-like hollow spheres, the metallasupramolecular chemistry of pentaphosphaferrocenes and CuBr2 afforded a conceptually new product, a compact 3.2 nm sized supramolecule [{1d}6(CuBr)32(CH3CN)6] formed by six largest pentaphosphaferrocene units [CpBIGFe(η5-P5)] (1d: CpBIG = η5-C5(4-nBuC6H4)5) so far and a framework of 32 copper and 32 bromide ions.

Synthesis and electrochemical properties of 3,4,5-tris(chlorophenyl)-1,2-diphosphaferrocenes

A novel representative of sodium 3,4,5-triaryl-1,2-diphosphacyclopentadienide containing a chloro substituent in the meta-position of the aryl groups was obtained with a high yield based on the reaction of tributyl(1,2,3-triarylcyclopropenyl)phosphonium bromide and sodium polyphosphides. Further reaction of sodium 3,4,5-tris(3-chlorophenyl)-1,2-diphosphacyclopentadienide with [FeCp(η6-C6H5CH3)][PF6] complex gives a new 3,4,5-tris(3-chlorophenyl)-1,2-diphosphaferrocene. The electrochemical properties of 3,4,5-tris(3-chlorophenyl)-1,2-diphosphaferrocene were studied and compared to 3,4,5-tris(4-chlorophenyl)-1,2-diphosphaferrocene. It was found that the position of the chlorine atom on the aryl fragment has an influence on the reduction potential of 1,2-diphosphaferrocenes, while the oxidation potentials do not change.

Synthesis, structure and electrochemical properties of 3,4,5-triaryl-1,2-diphosphaferrocenes

New 3,4,5-triaryl-1,2-diphosphaferrocenes [FeCp(η5-P2C3R3)] have been extensively studied experimentally (NMR, UV-Vis, electrochemical studies, X-ray) and quantum chemically.

Structural Chemistry of Giant Metal Based Supramolecules

The review presents a bird-eye view on the state of research in the field of giant nonbiological discrete metal complexes and ions of nanometer size, which are structurally characterized by means of single-crystal X-ray diffraction, using the crystal structure as a common key feature. The discussion is focused on the main structural features of the metal clusters, the clusters containing compact metal oxide/hydroxide/chalcogenide core, ligand-based metal-organic cages, and supramolecules as well as on the aspects related to the packing of the molecules or ions in the crystal and the methodological aspects of the single-crystal neutron and X-ray diffraction of these compounds.

The Missing Parent Compound [(C5 H5 )Fe(η5 -P5 )]: Synthesis, Characterization, Coordination Behavior and Encapsulation

The so far missing parent compound of the large family of pentaphosphaferrocenes [CpFe(η5 -P5 )] (1 b) was synthesized by the thermolysis of [CpFe(CO)2 ]2 with P4 using the very high-boiling solvent diisopropylbenzene. It was comprehensively characterized by, inter alia, NMR spectroscopy, single crystal X-ray structure analysis, cyclic voltammetry and DFT computations. Moreover, its coordination behavior towards CuI halides was explored, revealing the unprecedented 2D polymeric networks [{CpFe(η5:1:1:1:1 -P5 )}Cu2 (μ-X)2 ]n (2 a: X=Cl, 2 b: X=Br) and [{CpFe(η5:1:1 -P5 )}Cu(μ-I)]n (3) and even the first cyclo-P5 -containing 3D coordination polymer [{CpFe(η5:1:1 -P5 )}Cu(μ-I)]n (4). The sandwich complex 1 b can also be incorporated in nano-sized supramolecules based on [Cp*Fe(η5 -P5 )] (1 a) and CuX (X=Cl, Br, I): [CpFe(η5 -P5 )]@[{Cp*Fe(η5 -P5 )}12 (CuX)20-n ] (5 a: X=Cl, n=2.4; 5 b: X=Br, n=2.4; 5 c: X=I, n=0.95). Thereby, the formation of the CuI-containing fullerene-like sphere 5 c is found for the first time.

Au-Containing Coordination Polymers Based on Polyphosphorus Ligand Complexes

Whereas the self-assembly of pentaphosphaferrocenes [Cp^RFe(η⁵-P₅)] (Cp^R = Cp*, Cp^×, and Cp^Bn) with Cu and Ag salts has been well-studied in the past, the coordination chemistry toward Au complexes has been left untouched so far. Herein, the results of the self-assembly processes of [Cp^RFe(η⁵-P₅)] with Au salts of different anions (GaCl₄^-, SbF₆^-, and Al(OC(CF₃)₃)₄ (TEF^-)) are reported. Next to a variety of molecular coordination products, the first coordination polymers based on polyphosphorus ligand complexes and Au salts are also obtained. Thereby, a 2D coordination polymer comprising metal vacancies is isolated. In all products, the Au centers are coordinated in a linear or a trigonal planar environment. In solution, highly dynamic processes are observed. Variable-temperature NMR spectroscopy, solid-state NMR spectroscopy, and X-ray powder diffraction were applied to gain further insight into selected coordination compounds.

Self-assembled luminescent Cu(i) tetranuclear metallacycles based on 3,3′-bipyridine ligands

Three luminescent tetranuclear macrocycles are obtained selectively, applying coordination-driven supramolecular processes to the reaction of 3,3′-bipyridine ligand with in situ formed Cu(i) bimetallic units bearing a coordination angle of ca. 120°.

Metal-Deficient Supramolecule Based on a Fivefold-Symmetric Building Block

An unprecedented cationic supramolecule [(Cp''Fe(η5 -P5 ))12 {CuNCMe}8 ]8+ 2.66 nm in diameter was selectively isolated as a salt of the weakly coordinating anion [Al{OC(CF3 )3 }4 ]- for the first time and characterized by X-ray structure analysis, PXRD, NMR spectroscopy, and mass spectrometry. Its metal-deficient core contains the lowest possible number of Cu atoms to connect 12 pentaphosphaferrocene units, providing a supramolecule with fullerene topology which, topologically, also represents the simplest homologue in the family of metal-deficient pentaphosphaferrocene-based supramolecules [{CpR Fe(η5 -P5 )}12 (CuX)20-n ]. The 12 vacant metal sites between the cyclo-P5 rings, the largest number attained to date, make this compound a facile precursor for potential inner and outer modifications of the core as well as for functionalization via the substitution of labile acetonitrile ligands.