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

Cu(I) Complexes Comprising tetrahedral Mo2 E2 or Mo2 PE units (E=P, As, Sb) as Chelating Ligands

Novel isomorphous tetranuclear complexes, [(dppf)Cu(μ3 ,η2 : 2 : 2 -E2 {CpMo(CO)2 }2 ]BF4 [E=P (1), As (4), Sb (5), (dppf=1,1'-bis-(diphenylphosphino)-ferrocene)] and [(dppf)Cu(μ3 ,η2 : 2 : 2 -PE{CpMo(CO)2 }2 ]BF4 [E=As (2), Sb(3)] were synthesized from the reactions between [(dppf)Cu(MeCN)2 ][BF4 ] and tetrahedral molybdenum complexes containing unsubstituted homo- and hetero-diatomic group-15 elements [(μ,η2 : 2 -E2 {CpMo(CO)2 }2 ] [E=P (A), As (D), Sb (E)] and [(μ,η2 : 2 -PE{CpMo(CO)2 }2 ] [E=As (B), Sb (C)], respectively. In all these products, the {Mo2 E2 } or {Mo2 PE} moieties coordinate the Cu(I) center via a rare side-on η2 -coordination mode. The X-ray structure analyses of [(dppf)Cu(μ3 ,η2 : 2 : 1 -PSb{CpMo(CO)2 }2 ][BF4 ] demonstrate, for the first time, the utilization of an η1 -coordination mode for the ligand complex C to coordinate to the Cu(I) center. All the products were characterized by X-ray crystallography, NMR and IR spectroscopy, mass spectrometry and elemental analysis. Electrochemical studies also revealed the formation of 1-5, and, further, to understand the structure and bonding of the products, theoretical calculations using density functional theory (DFT) were conducted.

Icosidodecahedral Coordination-Saturated Cuprofullerene

The first coordination-saturated buckyball with a C60 molecule totally encased in an icosidodecahedral Cu30 in a (μ30 -(η2 )30 )-fashion, namely C60 @Cu30 @Cl36 N12 , has been successfully realized by a C60 -templated assembly. The 48 outmost coordinating atoms (36Cl+12N) comprise a new simple polyhedron that is described by a ccf topology. Charge transfer from (CuI , Cl) to C60 explains the expansion of the light absorption up to 700 nm, and accounts for an ultrafast photophysical process that underpins its high photothermal conversion efficiency. This work makes a giant step forward in exohedral metallofullerene (ExMF) chemistry.

Diantimony Complexes [CpR 2 Mo2 (CO)4 (μ,η2 -Sb2 )] (CpR =C5 H5 , C5 H4 t Bu) as Unexpected Ligands Stabilizing Silver(I)n (n=1-4) Monomers, Dimers and Chains

Synthesis and reactivity of transition metal compounds bearing "naked" pnictogen atoms is an active research area with remarkable bonding patterns observed in the formed compounds. Within this field, intense investigations on the coordination behavior of complexes possessing P_n and As_n (2≤n≤5) moieties have been conducted. However, studies on heavier analogues have been ignored so far due to arduous challenges related to low yields and moderate air stability. Herein, we present the first in-depth study addressing the reactivity of organometallic complexes containing Sb-donor atoms with several Ag^I salts. These reactions afforded twelve unprecedented aggregates as monomers, dimers as well as three- and four-membered chains of Ag^I ions claimed in the literature to be inaccessible. Interatomic distances as well as computational evidence obtained with help of several different methods suggest the presence of Ag⋅⋅⋅Ag interactions in all complexes containing more than one Ag^I ion.

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.

Versatile Coordination of AgI and CuI Ions towards cyclo-As5 Ligands

The reactions of the cyclo‐As₅ complex [Cp*Fe(η⁵‐As₅)] (B) with the Ag^I and Cu^I salts of the weakly coordinating anion (WCA) [FAl{OC₆F₁₀(C₆F₅)}₃]⁻ ([FAl]⁻) are studied. These reactions allow the synthesis of the mononuclear complexes [M(η⁵ : η²‐B)₂][FAl] (M=Ag (1), Cu (2)) when a ratio of B/M(FAl) 2 : 1 is used. Compound 1 shows an unusual disorder of the central Ag^I cation between two π‐coordinating cyclo‐As₅ ligands, which is absent in 2 pointing to a weak interaction of the Ag center towards the cyclo‐As₅ ligands in B. When the ratio of B/Ag(FAl) is changed to 3 : 1 or 1 : 1, the respective coordination compounds [Ag(η²‐B)₃][FAl] (3) and [Ag₂(η² : η²‐B)₂][FAl]₂ (4) are accessible. The coordination modes of the cyclo‐As₅ units in 1, 3 and 4 are all different, reflecting the adaptive coordination behavior of B towards Ag^I ions. The optimized geometries in the gas phase of 1–4 are determined by DFT calculations to support the bonding situation observed in their solid‐state structures.

Three-Component Self-Assembly Changes its Course: A Leap from Simple Polymers to 3D Networks of Spherical Host-Guest Assemblies

One‐pot self‐assembly reactions of the polyphosphorus complex [Cp*Fe(η⁵‐P₅)] (A), a coinage metal salt AgSbF₆, and flexible aliphatic dinitriles NC(CH₂)_xCN (x=1–10) yield 1D, 2D, and 3D coordination polymers. The seven‐membered backbone of the dinitrile was experimentally found as the borderline for the self‐assembly system furnishing products of different kinds. At x<7, various rather simple polymers are exclusively formed possessing either 0D or 1D Ag/A structural motifs connected by dinitrile spacers, while at x≥7, the self‐assembly switches to unprecedented extraordinary 3D networks of nano‐sized host–guest assemblies (SbF₆)@[(A)₉Ag₁₁]¹¹⁺ (x=7) or (A)@[(A)₁₂Ag₁₂]¹²⁺ (x=8–10) linked by dinitriles. The polycationic nodes represent the first superspheres based on A and silver and are host–guest able. All products are characterized by NMR spectroscopy, mass spectrometry, and single‐crystal X‐ray diffraction. The assemblies [(A)₁₂Ag₁₂]¹²⁺ were visualized by transmission electron microscopy.

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.

Mixed Organometallic-Organic Hybrid Assemblies Based on the Diarsene Complex [Cp2 Mo2 (CO)4 (μ,η2 -As2 )], AgI Salts and N-Donor Organic Molecules

The reaction of the organometallic diarsene complex [Cp2 Mo2 (CO)4 (η2 -As2 )] (1) with Ag[Al{OC(CF3 )3 }4 ] (Ag[TEF]) yielded the AgI monomer [Ag(η2 -1)3 ][TEF] (2). This compound exhibits dynamic behavior in solution, which allows directed selective synthesis of unprecedented organometallic-organic hybrid assemblies upon its reaction with N-donor organic molecules by a stepwise pathway, which is supported by DFT calculations. Accordingly, the reaction of 2 with 2,2'-bipyrimidine (L1) yielded the dicationic molecular compound [{(η2 -1)2 Ag}2 (μ-L1)][TEF]2 (3) or the 1D polymer [{(η2 -1)Ag}(μ-L1)]n [TEF]n (4) depending on the ratio of the reactants. However, its reactions with the pyridine-based linkers 4,4'-bipyridine (L2), 1,2-bis(4-pyridyl)ethylene (L3) and 1,2-bis(4-pyridyl)ethyne (L4) allowed the formation of the 2D polymers [{(η2 -1)Ag}2 (μ-Lx)3 ]n [TEF]2n [Lx=L2 (5), L3 (6), L4 (7), respectively]. Additionally, this concept was extended to step-by-step one-pot reactions of 1, [Ag(CH3 CN)3 ][Al{OC(CF3 )2 (CCl3 )}4 ] ([Ag(CH3 CN)3 ][TEFCl ]) and linkers L2-L4 to produce the 2D polymers [{(η2 -1)Ag}2 (μ,Lx)3 ]n [TEFCl ]2n [Lx=L2 (8), L3 (9), L4 (10), respectively].

Discrete and polymeric organometallic-organic assemblies based on the diarsene complex [(Cp)2Mo2(CO)4(μ,η2-As2)], AgPF6 and N-donor organic molecules

The first mixed-ligand self-assembly reactions of the diarsene complex [Cp₂Mo₂(CO)₄(μ,η²-As₂)] and N-donor organic molecules in the presence of AgPF₆ allow for the synthesis of two discrete and four polymeric supramolecular aggregates.

Linking of CuI Units by Tetrahedral Mo2 E2 Complexes (E=P, As)

The reaction of [Cp2 Mo2 (CO)4 (μ,η2:2 -E2 )] (A: E=P, B: E=As, Cp=C5 H5 ) with the WCA-containing CuI salts ([Cu(CH3 CN)4 ][Al{OC(CF3 )3 }4 ] (CuTEF, C), [Cu(CH3 CN)4 ][BF4 ] (D) and [Cu(CH3 CN)3.5 ][FAl{OC6 F10 (C6 F5 )}3 ] (CuFAl, E)) affords seven unprecedented coordination compounds. Depending on the E2 ligand complex, the counter anion of the copper salt and the stoichiometry, four dinuclear copper dimers and three trinuclear copper compounds are accessible. The latter complexes reveal first linear Cu3 arrays linked by E2 units (E=P, As) coordinated in an η2:1:1 coordination mode. All compounds were characterized by X-ray crystallography, NMR and IR spectroscopy, mass spectrometry and elemental analysis. To define the nature of the Cu⋅⋅⋅Cu⋅⋅⋅Cu interactions, DFT calculations were performed.

The Potential of the Diarsene Complex [(C5 H5 )2 Mo2 (CO)4 (μ,η2 -As2 )] as a Connector Between Silver Ions

The reaction of the organometallic diarsene complex [Cp₂Mo₂(CO)₄(μ,η²‐As₂)] (B) (Cp = C₅H₅) with Ag[FAl{OC₆F₁₀(C₆F₅)}₃] (Ag[FAl]) and Ag[Al{OC(CF₃)₃}₄] (Ag[TEF]), respectively, yields three unprecedented supramolecular assemblies [(η²‐B)₄Ag₂][FAl]₂ (4), [(μ,η¹:η²‐B)₃(η²‐B)₂Ag₃][TEF]₃ (5) and [(μ,η¹:η²‐B)₄Ag₃][TEF]₃ (6). These products are only composed of the complexes B and Ag^I. Moreover, compounds 5 and 6 are the only supramolecular assemblies featuring B as a linking unit, and the first examples of [Ag^I]₃ units stabilized by organometallic bichelating ligands. According to DFT calculations, complex B coordinates to metal centers through both the As lone pair and the As−As σ‐bond thus showing this unique feature of this diarsene ligand.

Use of a cyclo-P4 building block - a way to networks of host-guest assemblies

Despite the proven ability to form supramolecular assemblies via coordination to copper halides, organometallic building blocks based on four-membered cyclo-P4 ligands find only very rare application in supramolecular chemistry. To date, only three types of supramolecular aggregates were obtained based on the polyphosphorus end-deck complexes CpRTa(CO)2(η4-P4) (1a: CpR = Cp''; 1b: CpR = Cp'''), with none of them, however, possessing a guest-accessible void. To achieve this target, the use of silver salts of the weakly coordinating anion SbF6 - was investigated as to their self-assembly in the absence and in the presence of the template molecule P3Se4. The two-component self-assembly of the building block 1a and the coinage-metal salt AgSbF6 leads to the formation of 1D or 3D coordination polymers. However, when the template-driven self-assembly was attempted in the presence of an aliphatic dinitrile, the unprecedented barrel-like supramolecular host-guest assembly P3Se4@[{(Cp''Ta(CO)2(η4-P4))Ag}8]8+ of 2.49 nm in size was formed. Moreover, cyclo-P4-based supramolecules are connected in a 2D coordination network by dinitrile linkers. The obtained compounds were characterised by mass-spectrometry, 1H and 31P NMR spectroscopy and X-ray structure analysis.

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.

Functionalization of Pentaphosphorus Cations by Complexation

The chemistry of polyphosphorus cations has rapidly developed in recent years, but their coordination behavior has remained mostly unexplored. Herein, we describe the reactivity of [P5 R2 ]+ cations with cyclopentadienyl metal complexes. The reaction of [CpAr Fe(μ-Br)]2 (CpAr =C5 (C6 H4 -4-Et)5 ) with [P5 R2 ][GaCl4 ] (R=iPr and 2,4,6-Me3 C6 H2 (Mes)) afforded bicyclo[1.1.0]pentaphosphanes (1-R, R=iPr and Mes), showing an unsymmetric "butterfly" structure. The same products 1-R were formed from K[CpAr ] and [P5 R2 ][GaCl4 ]. The cationic complexes [CpAr Co(η4 -P5 R2 )][GaCl4 ] (2-R[GaCl4 ], R=iPr and Cy) and [(CpAr Ni)2 (η3:3 -P5 R2 )][GaCl4 ] (3-R[GaCl4 ]) were obtained from [P5 R2 ][GaCl4 ] and [CpAr M(μ-Br)]2 (M=Co and Ni) as well as by using low-valent "CpAr MI " sources. Anion metathesis of 2-R[GaCl4 ] and 3-R[GaCl4 ] was achieved with Na[BArF24 ]. The P5 framework of the resulting salts 2-R[BArF24 ] can be further functionalized with nucleophiles. Thus reactions with [Et4 N]X (X=CN and Cl) give unprecedented cyano- and chloro-functionalized complexes, while organo-functionalization was achieved with CyMgCl.

The Potential of the Diphosphorus Complex [Cp2W2(CO)4(η2-P2)] as an Organometallic Connecter in Supramolecular Chemistry

For the first time, the tetrahedral diphosphorus complex [Cp2W2(CO)4(µ,η2:η2-P2)] (Cp = C5H5) (3) is used as a connecter in supramolecular chemistry. The treatment of 3 with CuI halides leads to the formation of the new one-dimensional (1D) linear polymers [Cu(µ-X){Cp2W2(CO)4(µ,η2:η2:η1:η1-P2)}] n {X = Cl (4), Br (5), I (6)}. The coordination polymers (CPs) 4-6 are almost insoluble in organic solvents, thus, their 31P MAS-NMR spectra were recorded and found to be remarkably influenced by their solid-state structures. Additionally, we demonstrate that by reacting the Cp-substituted diphosphorus complex [Cp'2W2(CO)4(µ,η2:η2-P2)] {Cp' = C5H4{C(CH3)3}} (7) with CuBr, the unprecedented soluble 1D CP [Cu(µ-Br){Cp'2W2(CO)4(µ,η2:η2:η1:η1-P2)}] n (8) is obtained. Furthermore, the reactions of 3 with the AgI salts Ag[CF3SO3] and Ag[PF6] result in the formation of the oligomeric dicationic species [Ag2{Cp2W2(CO)4(µ,η2:η2:η2-P2)}2 {Cp2W2(CO)4(µ,η2:η2:η1:η1-P2)}2][X']2 {X' = [CF3SO3]- (9), [PF6]- (10)}.

The Potential of Molybdenum Complexes Bearing Unsubstituted Heterodiatomic Group 15 Elements as Linkers in Supramolecular Chemistry

The reactions of tetrahedral molybdenum complexes bearing unsubstituted heterodiatomic Group 15 elements, [Cp₂ Mo₂ (CO)₄ (μ,η² :η² -PE)] (Cp=C₅ H₅ ; E=As (1), Sb (2)), with Cu^I halides afforded seven unprecedented neutral supramolecular assemblies. Depending on the Mo₂ PE units and the Cu^I halide, the oligomers [⟨{Cp₂ Mo₂ (CO)₄ }{μ₄ ,η² :η² :η² :η¹ -PE}⟩₄ ⟨{CuX}{Cu(μ-X)}⟩₂ ] (E=As (X=Cl (3), Br (4)); E=Sb (X=Cl (6), Br (7))) or the 1D coordination polymers [{Cp₂ Mo₂ (CO)₄ }{μ₄ ,η² :η² :η¹ :η¹ -PAs}{Cu(μ-I)}]_n (5) and [{Cp₂ Mo₂ (CO)₄ }{μ₄ ,η² :η² :η² :η¹ -PSb}₂ {Cu(μ-X)}₃ ]_n (X=I (8), Br (9)) are accessible. These solid-state aggregates are the first and only examples featuring the organometallic heterodiatomic Mo₂ PE complexes 1 and 2 as linking moieties. DFT calculations demonstrate that complexes 1 and 2 present a unique class of mixed-donor ligands coordinating to Cu^I centers via the P lone pair and the P-E σ-bond, revealing an unprecedented coordination mode.

From nano-balls to nano-bowls

Pentaphosphaferrocene [Cp*Fe(η5-P5)] in combination with Cu(i) halides is capable of a template-directed synthesis of fullerene-like spheres. Herein, we present the use of a triple decker complex as template that leads to the formation of unprecedented 'nano-bowls'. These spherical domes resemble the truncated fullerenes I h-C80 and represent a novel spherical arrangement in the chemistry of spherical molecules.

Organometallic-Organic Hybrid Polymers Assembled from Pentaphosphaferrocene, Bipyridyl Linkers, and CuI Ions

A multicomponent approach of the P n ligand complex [Cp*Fe(η5-P5)] (1: Cp* = η5-C5Me5) with the ditopic organic linkers 4,4'-bipyridine (2) or trans-1,2-di(pyridine-4-yl)ethene (3) in the presence of CuI salts of the anions [BF4]- and [PF6]- or the coordinating anion Br-, leads to the formation of four novel organometallic-organic hybrid polymers: the cationic 1D polymeric compounds [Cu4{Cp*Fe(µ3,η5:1:1-P5)}2(µ,η1:1-C10H8N2)4(CH3CN)4] n [BF4]4n (4) and [Cu4{Cp*Fe(µ3,η5:1:1-P5)}2(µ,η1:1-C10H8N2)4(CH3CN)4] n [PF6]4n (5) as well as the unique neutral threefold 2D → 2D interpenetrated networks [Cu2Cl2{Cp*Fe(µ3,η5:1:1-P5)}(µ,η1:1-C12H10N2)] n (6) and [Cu2Br2{Cp*Fe(µ3,η5:1:1-P5)}(µ,η1:1-C10H8N2)] n (7).

Anionic Hosts for the Incorporation of Cationic Guests

Pentaphosphaferrocene [Cp*Fe(η5 -P5 )] (1 a) represents an excellent building block for the template-directed synthesis of spherical supramolecules. Here, the self-assembly of 1 a with CuI and CuII halides in the presence of the template complexes [FeCp2 ][PF6 ], [CoCp2 ][PF6 ] and [CoCp2 ] is reported, testifying to the redox behavior of the formed supramolecules. The oxidation or reduction capacity of these reactive complexes does not inhibit their template impact and, for the first time, the cationic metallocene [CoCp2 ]+ is enclosed in unprecedented anionic organometallic hosts. Furthermore, the large variety of structural motifs, as icosahedral, trigonal antiprismatic, cuboidal and tetragonal antiprismatic arrangements of 1 a units are realized in the supramolecules [FeCp2 ]@[{1 a}12 (CuBr)17.3 ] (3), [CoCp2 ]+3 {[CoCp2 ]+ @[{1 a}8 Cu24.25 Br28.25 (CH3 CN)6 ]4- } (4), {[Cp2 Co]+ @[{1 a}8 (CuI)28 (CH3 CN)9.8 ]}{[Cp2 Co]+ @[{1 a)}8 Cu24.4 I26.4 (CH3 CN)8 ]2- } (5), and [{1 a}3 {(1 a)2 NH}3 Cu16 I10 (CH3 CN)7 ] (6), respectively.

Neutral two-dimensional organometallic–organic hybrid polymers based on pentaphosphaferrocene, bipyridyl linkers and CuCl

The reaction of the P_n ligand complex [Cp*Fe(η⁵-P₅)] (1: Cp* = η⁵-C₅Me₅) with CuCl in the presence of 4,4′-bipyridine or 1,2-di(4-pyridyl)ethylene leads to the formation of three unprecedented neutral 2D organometallic–organic hybrid networks.

Tuning the dimensionality of organometallic–organic hybrid polymers assembled from [Cp2Mo2(CO)4(η2-P2)], bipyridyl linkers and AgI ions

The first of its kind study of the effect of the organic linker length and reaction temperature on aggregation reactions leading to organometallic–organic hybrid polymers is presented.

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

Pentaphosphaferrocenes [CpR Fe(η5 -P5 )] (1) and CuI halides are excellent building blocks for the formation of discrete supramolecules. Herein, we demonstrate the potential of Cu(CF3 SO3 ) for the construction of the novel 2D polymer [{Cp*Fe(μ4 ,η5:1:1:1 -P5 )}{Cu(CF3 SO3 )}]n (2) and the unprecedented nanosphere (CH2 Cl2 )1.4 @[{CpBn Fe(η5 -P5 )}12 {Cu(CF3 SO3 )}19.6 ] (3). The supramolecule 3 has a unique scaffold beyond the fullerene topology, with 20 copper atoms statistically distributed over the 30 vertices of an icosidodecahedron. Combinatorics was used to interpret the average disordered structure of the supramolecules. In this case, only two pairs of enantiomers with D5 and D2 symmetry are possible for bidentate bridging coordination of the triflate ligands. DFT calculations showed that differences in the energies of the isomers are negligible. The benzyl ligands enhance the solubility of 3, enabling NMR-spectroscopic and mass-spectrometric investigations.