Triple-decker Complexes Research Articles

Triple-decker complexes incorporating three distinct deck architectures.

The reactivity of the dilithioplumbole ([Li2(thf)2(μ,η5-LPb)], LPb = 1,4-bis-tert-butyl-dimethylsilyl-2,3-bis-phenyl-plumbolyl) towards the reactive pnictogen precursors P4, pentaphosphaferrocene, and pentaarsaferrocene ([Cp*Fe(η5-E5)] (Cp* = η5-C5Me5, E = P, As)) is reported. The reaction with P4 afforded a phospholyl lithium complex, via lead-phosphorus exchange, while the reactions with [Cp*Fe(η5-E5)] yielded the first examples of Pb-Fe-Li heterotrimetallic triple-decker polypnictogenides with three different deck motifs.

Planar triple-decker and capped octahedral clusters of group-6 transition metals

Recent isolation and structural characterization of a planar triple-decker metallaborane complex of tungsten prompted us to synthesize its molybdenum analogue. Therefore, we have explored the thermolysis reaction of the intermediates obtained from the low-temperature reaction of [Cp*MoCl4] (Cp* = η5-C5Me5) and LiBH4 with Co2(CO)8. The reaction indeed produced the analogous triple-decker complex of molybdenum with a planar middle-deck [(Cp*Mo)2{µ-η6:η6-B4H4Co2(CO)5}(H)2], 1, along with the formation of the reported [(Cp*Mo)2B5H9] metallaborane. In an effort to isolate multi-decker complexes with a different geometries, we have also further explored the thermolysis reaction of the intermediates obtained from the low-temperature reaction of [Cp*WCl4] and LiBH4 with Co2(CO)8. The reaction afforded an octahedral cluster, [{Cp*W(CO)2}2(µ-H)2B3H3Co2(CO)4], 2, along with the formation of the bimetallic cluster [(Cp*W)2B3H3(µ-H)2Co2(CO)4(µ-CO)2], 3. The cage geometry of compound 2 is based on an octahedron with one additional vertex capping a trigonal face. That of compound 3 is a bicapped trigonal-bipyramidal analogue to the parent compound [(Cp*W)2B5H9]. While compound 1 has been characterized by various spectroscopic analyses, compounds 2 and 3 have been characterized by multiple spectroscopic and single-crystal X-ray diffraction analyses. Density-functional theory (DFT) calculations account for their stability and structural variation.

NMR thermosensing properties on binuclear triple-decker complexes of terbium(III) and dysprosium(III) with 15-crown-5-phthalocyanine

In this paper, we have firstly demonstrated the thermosensing properties of binuclear triple-decker terbium(III) and dysprosium(III) complexes with 15-crown-5-phthalocyanine Tb2[(15C5)4Pc]3 (I) and Dy2[(15C5)4Pc]3 (II) in the physiological temperature range (303–323 K). Measuring the LIS values for I and II in CDCl3 has revealed high temperature sensitivity for the signals of the aromatic protons of the inner deck of the complexes: ∂δ/∂T = 1.1 and 0.55 ppm/K for I and II, respectively. Terbium-containing complex I has the highest sensitivity of the LIS among the published complexes of 4f and d elements with polydentate ligands in organic media. A significant impact of the Curie-spin contribution to the paramagnetic spin–spin relaxation rate enhancement has been found, which has a pronounced temperature dependence.The results obtained for kinetically and thermodynamically stable Ln2[(15C5)4Pc]3 complexes allow one to consider them pronounced NMR thermosensors in nonpolar solutions. The possibility of the solubilization of complex I in aqueous media due to the presence of crown ether moieties has been also demonstrated.

High-selective room-temperature NO2 sensors based on a coumarin-substituted tris(phthalocyaninato) europium

A novel coumarin-substituted phthalocyaninato triple-decker complex, Eu2[Pc(Cou)4]3 is designed and synthesized successfully. Introduction of the coumarin substituents onto the periphery of a phthalocyanine ring in the sandwich-type phthalocyaninato triple-decker not only increased the solubility and improved the film-forming ability, but also importantly ensured the suitable HOMO and LUMO energy levels. The solution-processed thin film of the Eu2[Pc(Cou)4]3 was prepared by a simple and low-cost quasi–Langmuir–Shäfer (QLS) method and applied as the gas sensor for the detection of NO2. Importantly, within the dynamic exposure period of 1 min, balanced, stable, a reproducible [Formula: see text]-type response to electron-accepting gas NO2 in the range of 4–35 ppm, was revealed, based on the QLS film of Eu2[Pc(Cou)4]3 complex at room temperature, dependant on the optimized molecular packing in [Formula: see text]-aggregation mode with a large specific surface area and good film conductivity.

Redox Chemistry of Heterobimetallic Polypnictogen Triple-Decker Complexes - Rearrangement, Fragmentation and Transfer.

The redox chemistry of the heterobimetallic triple‐decker complexes [(Cp*Fe)(Cp′′′Co)(μ,η5:η4‐E5)] (E=P (1), As (2), Cp*=1,2,3,4,5‐pentamethyl‐cyclopentadienyl, Cp′′′=1,2,4‐tri‐tertbutyl‐cyclopentadienyl) and [(Cp′′′Co)(Cp′′′Ni)(μ,η3:η3‐E3)] (E=P (10), As (11)) was investigated. Compound 1 and 2 could be oxidized to the monocations 3 and 4 and further to the dications 5 and 6, while the initially folded cyclo‐E5 ligand planarizes upon oxidation. The reduction leads to an opposite change in the geometry of the middle deck, which is now folded stronger into the direction of the other metal fragment (formation of monoanions 7 and 8). For the arsenic compound 8, a different behavior is found since a fragmentation into an As6 (9) and As3 ligand complex occurs. The Co and Ni triple‐decker complexes 10 and 11 can be oxidized initially to the heterometallic monocations 12 and 13, which are not stable in solution and convert selectively into the homometallic nickel complexes 14 and 15 and the cobalt complexes 16 and 17. This behavior was further proven by the oxidation of [(Cp′′′Co)(Cp′′Ni)(μ,η3:η2‐P3)] (19, Cp′′=1,3‐di‐tertbutyl‐cyclopentadienyl) comprising two different Cp ligands. The transfer of {CpRM} fragments can be suppressed when a {W(CO)5} unit is coordinated to the P3 ligand (20) prior to the oxidation and the mixed cobalt and nickel cation 21 can be isolated. The reduction of 10 and 11 yields the heterometallic monoanions 22 and 23, where no transfer of the {CpRM} fragments is observed.

Triple-Decker Sandwich Complexes of Tungsten with Planar and Puckered Middle Decks.

A triple-decker complex of tungsten, [(Cp*W)2{μ-η6:η6-B4H4Co2(CO)5}(H)2] (1; Cp* = η5-C5Me5), with a planar middle deck has been isolated by thermolysis of an in situ formed intermediate from the reaction of Cp*WCl4 and LiBH4 with Co2(CO)8. In addition, we have also isolated another triple-decker complex, [(Cp*W)2{μ-η6:η6-B5H5Fe(CO)3}(H)2] (4), having a puckered central ring, from a similar reaction with Fe2(CO)9. Clusters 1 and 4 are unprecedented examples of a triple-decker complex having a 24-valence electron with bridging hydrogen atoms.

"Triple-Decker Sandwich" Containing Planar {B2E2Pd} Ring (E = S or Se).

In an effort to generate triple-decker complexes comprising a {PdCl2}moiety in the middle deck, we have explored the reactivity of [(Cp*M)2{μ-B2H2E2}], 1-4 (1: M = Co, E = S; 2: M = Co, E = Se; 3: M = Rh, E = Se; and 4: M = Ir, E = Se; Cp* = η5-C5Me5), with [PdCl2(COD)] (COD = 1,5-cyclooctadiene). The reactions led to the formation of a series of trinuclear heterometallic triple-decker complexes, [(Cp*M)2{μ-B2H2E2Pd(Cl)2}], 5-8 (5: M = Co, E = S; 6: M = Co, E = Se; 7: M = Rh, E = Se; and 8: M = Ir, E = Se). Formation of the complexes 5-8 occurred almost instinctively as a single product with the elimination of the COD ligand. These complexes are examples of novel triple-decker species having a planar bridging palladacycle ligand, in which the Pd metal exists as Pd(II) in an uncommon pseudo-octahedral environment with an elongated M-Pd bonding interaction. The new species, 5-8, have been characterized spectroscopically, and the structures of 5-7 were confirmed by single-crystal X-ray diffraction studies. The structure and bonding of these molecules were further analyzed with the help of density functional theory studies that found a strong electron donation from the B2E2 (E = S or Se) fragment of the middle ring to the axial metals, while a weak bonding interaction between group 9 metals and Pd.

Stack by Stack: From the Free Cyclopentadienylgermanium Cation Via Heterobimetallic Main-Group Sandwiches to Main-Group Sandwich Coordination Polymers.

Heterobimetallic cationic sandwich complexes [M(μ‐Cp)M′Cp]+ of group 13 (M=Ga, In) and group 14 (M′=Ge, Sn) elements have been prepared as [WCA]− salts (WCA=Al(ORF)4; ORF=OC(CF3)3). Their molecular structures include free apical gallium or indium atoms. The sandwich complexes were formed in the reactions of [M(HMB)]+[WCA]− (HMB=C6Me6) with the free metallocenes [M′Cp2]. Their structures are related to known stannocene and stannocenium salts; the unprecedented germanium analogues, namely the free germanocenium cation [GeCp]+ and the corresponding triple‐decker complex cation [CpGe(μ‐Cp)GeCp]+, are described herein. By variation of the reaction conditions, these sandwich complexes can be transformed into the group 13/14 mixed cationic coordination polymer [{In(HMB)(μ‐SnCp2)}n][WCA]n. This polymeric chain motif was also successfully replicated by the synthesis of complexes [{Ga/In(HMB)(μ‐FeCp2)}n][WCA]n containing FeCp2 as a bridging ligand.

Iodination of cyclo-E5 -Complexes (E=P, As).

In a high‐yield one‐pot synthesis, the reactions of [Cp*M(η5‐P5)] (M=Fe (1), Ru (2)) with I2 resulted in the selective formation of [Cp*MP6I6]+ salts (3, 4). The products comprise unprecedented all‐cis tripodal triphosphino‐cyclotriphosphine ligands. The iodination of [Cp*Fe(η5‐As5)] (6) gave, in addition to [Fe(CH3CN)6]2+ salts of the rare [As6I8]2− (in 7) and [As4I14]2− (in 8) anions, the first di‐cationic Fe‐As triple decker complex [(Cp*Fe)2(μ,η5:5‐As5)][As6I8] (9). In contrast, the iodination of [Cp*Ru(η5‐As5)] (10) did not result in the full cleavage of the M−As bonds. Instead, a number of dinuclear complexes were obtained: [(Cp*Ru)2(μ,η5:5‐As5)][As6I8]0.5 (11) represents the first Ru‐As5 triple decker complex, thus completing the series of monocationic complexes [(CpRM)2(μ,η5:5‐E5)]+ (M=Fe, Ru; E=P, As). [(Cp*Ru)2As8I6] (12) crystallizes as a racemic mixture of both enantiomers, while [(Cp*Ru)2As4I4] (13) crystallizes as a symmetric and an asymmetric isomer and features a unique tetramer of {AsI} arsinidene units as a middle deck.

Oxidation-Induced Detachment of Ruthenoarene Units and Oxygen Insertion in Bis-Pd(II) Hexaphyrin π-Ruthenium Complexes.

Two types of new bis-Pd(II) hexaphyrin π-ruthenium complexes are reported. A double-decker bis-Pd(II) hexaphyrin π-ruthenium complex 4 was obtained by oxidation-induced detachment of a ruthenoarene unit from the triple-decker complex 3 and oxygen-inserted triple-decker bis-Pd(II) hexaphyrin π-ruthenium complex 6 was obtained upon treatment of bis-Pd(II) [26]hexaphyrin 5 with [RuCl2(p-cymene)]2 under aerobic conditions. Although π-metal complexation of porphyrinoids often results in decreased global aromaticity due to the enhancement of local 6π aromatic segments, distinct aromatic characters were indicated for 4 and 6 by 1H-NMR spectral and theoretical calculations. These results are accounted for in terms of possible resonance contributors of hexaphyrin di- and tetraanion ligands. Thus, π-metal coordination has been shown to be effective for modulation of the overall aromaticity.

Coexistence of Spin-Lattice Relaxation and Phonon-Bottleneck Processes in GdIII -Phthlocyaninato Triple-Decker Complexes under Highly Diluted Conditions.

Gd3+ complexes have been shown to undergo unusual slow magnetic relaxation processes similar to those of single-molecule magnets (SMMs), even though Gd3+ does not exhibit strong magnetic anisotropy. To reveal the origin of the slow magnetic relaxation of Gd3+ complexes, we have investigated the magnetic properties and heat capacities of two Gd3+ -phthalocyaninato triple-decker complexes, one of which has intramolecular Gd3+ -Gd3+ interactions and the other does not. It was found that the Gd3+ -Gd3+ interactions accelerate the magnetic relaxation processes. In addition, magnetically diluted samples, prepared by doping a small amount of the Gd3+ complexes into a large amount of diamagnetic Y3+ complexes, underwent dual magnetic relaxation processes. A detailed dynamic magnetic analysis revealed that the coexistence of spin-lattice relaxation and phonon-bottleneck processes is the origin of the dual magnetic relaxation processes.

Synthesis of a Heterobimetallic Arsenic Triple-Decker Complex and Its Fragmentation Chemistry

The synthesis of the metastable triple-decker complex [(Cp*Fe)(Cp‴Co)(μ,η5:η4-As5)] (3) (Cp* = pentamethyl-cyclopentadienyl, Cp‴ = 1,2,4-tritertbutyl-cyclopentadienyl) is reported. 3 is sensitive t...

Syntheses, structures and mössbauer effect spectroscopy of triple-decker complexes incorporating decamethylferrocene

Two new triple-decker complexes were synthesized by the reaction of decamethylferrocene Cp∗FeCp∗ (Cp∗ = C5Me5) with ruthenium cations, [CpRu]+ (Cp = C5H5) and [Cp∗Ru]+. The reaction of [CpRu]+ with Cp∗FeCp∗ afforded a purple colored heterometallic complex [CpRu(μ-Cp∗)FeCp∗]+ by electrophilic addition of ruthenium to one Cp∗ ring of decamethylferrocene in 13.3% yield. In analogous manner, the reaction of [Cp∗Ru]+ with Cp∗FeCp∗ afforded a magenta colored complex [Cp∗Ru(μ-Cp∗)FeCp∗]+ in 22.5% yield. Two air stable triple-decker complexes incorporating decamethylferrocene, [CpRu(μ-Cp∗)FeCp∗]+ (1) and [Cp∗Ru(μ-Cp∗)FeCp∗]+ (2) have been characterized by NMR spectroscopy, elemental analysis, single-crystal X-ray diffraction analysis, cyclic voltammetry and temperature dependent 57Fe Mössbauer spectroscopy.

A voltammetry biosensor based on self-assembled layers of a heteroleptic tris(phthalocyaninato) europium triple-decker complex and tyrosinase for catechol detection

A highly efficient enzyme-based sensor was made from a heteroleptic tris(phthalocyaninato) europium triple-decker complex Eu2(Pc)[Pc(OPh)8]2, for the first time. The ITO working electrode was modified by a mixture of hybrid multi-layers consisting of Eu2(Pc)[Pc(OPh)8]2, stearic acid (SA) and tyrosinase (Tyr) (Eu2(Pc)[Pc(OPh)8]2/SA/Tyr-ITO) using the Langmuir-Blodgett (LB) technique. The microstructure and morphology of the resulting LB films can be characterized by their π–A isotherms, UV–vis absorption spectra, X-ray diffraction and atomic force microscopy (AFM) analysis. The experimental results revealed that the triple-decker molecules of Eu2(Pc)[Pc(OPh)8]2 take a H-type molecular stacking mode in both pure and mixed LB film, and the microstructures of films were effectively improved by mixing SA within the triple-decker Eu2(Pc)[Pc(OPh)8]2 molecules. The excellent electrocatalytic effect of the Eu2(Pc)[Pc(OPh)8]2/SA/Tyr LB films, leads to a good linear increase from 5.26 × 10−7 to 2.1 × 10−4 M for catechol. It also leads to an excellent sensitivity of 2.19 μA/μM, and a detection limits of 6.29 × 10−8 M (S/N = 3) of catehol at the oxidation peak, achieving best catechol sensing performance among the phthalocyanine-based biosensing mediators. The reduction peak also showed a good linear increase from 5.26 × 10−7 to 1.60 × 10−4 M for catechol with a sensitivity of 0.615 μA/μM, and a detection limit of 1.69 × 10−7 M (S/N = 3). Moreover, the Eu2(Pc)[Pc(OPh)8]2/SA/Tyr-ITO electrode are easy to reproduce, stable and resistant to interference when it comes to detection for catehol, and this indicates great potential of industrial application of tris(phthalocyaninato) rare earth complexes in ultrasensitive and specific biosensors.

Manipulation of the Coordination Geometry along the C4 Rotation Axis in a Dinuclear Tb3+ Triple-Decker Complex via a Supramolecular Approach.

A supramolecular complex (1⋅C60 ) was prepared by assembling (C60-Ih)[5,6]fullerene (C60 ) with the dinuclear Tb3+ triple-decker complex [(TPP)Tb(Pc)Tb(TPP)] (1: Tb3+ =trivalent terbium ion, Pc2- =phthalocyaninato, TPP2- =tetraphenylporphyrinato) with quasi-D4h symmetry to investigate the relationship between the coordination symmetry and single-molecule magnet (SMM) properties. Tb3+ -Pc triple-decker complexes (Tb2 Pc3 ) have an important advantage over Tb3+ -Pc double-decker complexes (TbPc2 ) since the magnetic relaxation processes correspond to the Zeeman splitting when there are two 4f spin systems. The two Tb3+ sites of 1 are equivalent, and the twist angle (φ) was determined to be 3.62°. On the other hand, the two Tb3+ sites of 1⋅C60 are not equivalent. The φ values for sites Tb1 and Tb2 were determined to be 3.67° and 33.8°, respectively, due to a change in the coordination symmetry of 1 upon association with C60 . At 1.8 K, 1 and 1⋅C60 undergo different magnetic relaxations, and the changes in the ground state affect the spin dynamics. Although 1 and 1⋅C60 relax via QTM in a zero applied magnetic field (H), H dependencies of the magnetic relaxation times (τ) for H>1500 Oe are similar. On the other hand, for H<1500 Oe, the τ values have different behaviors since the off-diagonal terms ( ) affect the magnetic relaxation mechanism. From temperature (T) and H dependences of τ, spin-phonon interactions along with direct and Raman mechanisms explain the spin dynamics. We believe that a supramolecular method can be used to control the magnetic anisotropy along the C4 rotation axis and the spin dynamic properties in dinuclear Ln3+ -Pc multiple-decker complexes.

A General Pathway to Heterobimetallic Triple‐Decker Complexes

A systematic study on the reactivity of the triple‐decker complex [(Cp’’’Co)2(μ,η4:η4‐C7H8)] (A) (Cp’’’=1,2,4‐tritertbutyl‐cyclopentadienyl) towards sandwich complexes containing cyclo‐P3, cyclo‐P4, and cyclo‐P5 ligands under mild conditions is presented. The heterobimetallic triple‐decker sandwich complexes [(Cp*Fe)(Cp’’’Co)(μ,η5:η4‐P5)] (1) and [(Cp’’’Co)(Cp’’’Ni)(μ,η3:η3‐P3)] (3) (Cp*=1,2,3,4,5‐pentamethylcyclopentadienyl) were synthesized and fully characterized. In solution, these complexes exhibit a unique fluxional behavior, which was investigated by variable temperature NMR spectroscopy. The dynamic processes can be blocked by coordination to {W(CO)5} fragments, leading to the complexes [(Cp*Fe)(Cp’’’Co)(μ3,η5:η4:η1‐P5){W(CO)5}] (2 a), [(Cp*Fe)(Cp’’’Co)(μ4,η5:η4:η1:η1‐P5){(W(CO)5)2}] (2 b), and [(Cp’’’Co)(Cp’’’Ni)(μ3,η3:η2:η1‐P3){W(CO)5}] (4), respectively. The thermolysis of 3 leads to the tetrahedrane complex [(Cp’’’Ni)2(μ,η2:η2‐P2)] (5). All compounds were fully characterized using single‐crystal X‐ray structure analysis, NMR spectroscopy, mass spectrometry, and elemental analysis.

Relationship between the Coordination Geometry and Spin Dynamics of Dysprosium(III) Heteroleptic Triple-Decker Complexes

When using single molecule magnets (SMMs) in spintronics devices, controlling the quantum tunneling of the magnetization (QTM) and spin-lattice interactions is important. To improve the functionality of SMMs, researchers have explored the effects of changing the coordination geometry of SMMs and the magnetic interactions between them. Here, we report on the effects of the octa-coordination geometry on the magnetic relaxation processes of dinuclear dysprosium(III) complexes in the low-temperature region. Mixed ligand dinuclear Dy3+ triple-decker complexes [(TPP)Dy(Pc)Dy(TPP)] (1), which have crystallographically equivalent Dy3+ ions, and [(Pc)Dy(Pc)Dy(TPP)] (2), which have non-equivalent Dy3+ ions, (Pc2− = phthalocyaninato; TPP2− = tetraphenylporphyrinato), undergo dual magnetic relaxation processes. This is due to the differences in the ground states due to the twist angle (φ) between the ligands. The relationship between the off-diagonal terms and the dual magnetic relaxation processes that appears due to a deviation from D4h symmetry is discussed.

Phenyl-substituted terbium(III) single- and multiple-decker phthalocyaninates: Synthesis, physicochemical properties and peculiarities of self-assembly in solid phase

Selective synthetic approaches to novel single- and multiple-decker terbium(III) phthalocyaninates, bearing peripheral phenyl groups, were developed. The compounds were identified by nuclear magnetic resonance spectroscopy, high resolution mass spectrometry, Fourier-transform infrared and UV–Vis spectroscopy. From the X-ray data for initial 1,2-dicyano-4,5-diphenylbenzene it was shown that phenyl groups are not in the same plane, and dihedral angle between them equals 64°. Strong upfield shifts of the aromatic proton signals up to −131.62 ppm in the case of a triple-decker complex were found in the nuclear magnetic resonance spectra due to paramagnetic nature of terbium(III) ion. Stronger intramolecular interactions are observed for the sandwich-type phenyl-substituted terbium complexes comparing to tert-butyl-substituted analogs, earlier described in literature. In the case of the double-decker compound, this results in 142 nm hypsochromic shift of the intervalence absorption band. DC conductivity measurements were carried out for terbium(III) phthalocyaninates. The formation of the ring-shaped self-assembled aggregates with a diameter of 400 nm was observed in thin solid films of the prepared terbium(III) compounds by atomic force microscopy.

Syntheses and Structures of Triple-Decker Complexes Incorporating Octamethylruthenocene and Nonamethylruthenocene

Five new diruthenium triple-decker complexes were synthesized by the reaction of ruthenium electrophiles with metallocenes of ruthenium. At 40 °C, the reaction of [(C5R5)Ru(NCMe)3]+ (R = H, Me) wit...

π-Ruthenium Complexes of Hexaphyrins(1.1.1.1.1.1): A Triple-Decker Complex Bearing Two Ruthenoarene Units.

Ruthenium(II) π-coordination onto [28]hexaphyrins(1.1.1.1.1.1) has been accomplished. Reactions of bis-AuIII and mono-AuIII complexes of hexakis(pentafluorophenyl) [28]hexaphyrin with [RuCl2 (p-cymene)]2 in the presence of NaOAc gave the corresponding π-ruthenium complexes, in which the [(p-cymene)Ru]II fragment sat on the deprotonated side pyrrole. A similar reaction of the bis-PdII [26]hexaphyrin complex afforded a triple-decker complex, in which the two [(p-cymene)Ru]II fragments sat on both sides of the center of the [26]hexaphyrin framework.