Heterotrimetallic Complex Research Articles

Hetero-trimetallic complexes comprising bridging boryl and borylene ligands: an experimental and theoretical study.

In an effort to explore the coordination chemistry of the coordinative sulfur centers in arachno-ruthenaborane [(Cp*Ru)2(B3H8)(CS2H)] (arachno-1), we have thermolyzed arachno-1 with group-6 metal carbonyls [M(CO)5·THF] (M = Cr, Mo and W). The reaction of arachno-1 with [Cr(CO)5·THF] resulted in the formation of hetero-trimetallic triply bridging borylene [(Cp*Ru)2(μ-CO)(μ3-CH2S2-κ2S':κ2S''){Cr(CO)3}(μ3-BH)] (2), bridging boryl-borylene [(Cp*Ru)2(μ-CO){(μ3-BH(CH2S2)-κ2B:κ2S':κ1S'')}{Cr(CO)3}(μ3-BH)] (3), and sulfido bridged hetero-trimetallic complex [(Cp*Ru)2(μ-CO)3{Cr(CO)3}(μ3-S)] (4). In 2, one side of Ru2Cr-triangle features a μ3-BH ligand while the other side is quadruply bridged by a methanedithiolato ligand in an unsymmetrical fashion. Unlike 2, in complex 3, one side of the Ru2Cr-triangle has a μ3-BH ligand while the opposite side is bridged by a boryl ligand BH(CH2S2) in an unsymmetrical way (μ3-κ2:κ2:κ1) to the metal centers. Interestingly, when the similar reactions of arachno-1 were performed with heavier group-6 metal carbonyls [M(CO)5·THF] (M = Mo and W), it led to the formation of methanedithiolato bridged hetero-trimetallic chain complexes, [{Cp*Ru(CO)}2(μ-CO)2(μ3-CH2S2-κ2S':κ2S''){M(CO)2}] (5, M = Mo; 6, M = W) and sulfido-bridged hetero-trimetallic complexes [(Cp*Ru)2(μ-CO)3{M(CO)3}(μ3-S)] (7, M = Mo; 8, M = W), analogous to 4. In complexes 5 and 6, a Ru2M-chain is symmetrically bridged by a methanedithiolato ligand. On the other hand, in complexes 4, 7, and 8, a sulfido ligand coordinates to two ruthenium and one group-6 metal atoms in μ3-fashion. All the complexes have been characterized by 1H NMR, 13C NMR, UV-vis, IR spectroscopy, and mass spectrometry and their structural architectures have been unambiguously established by single crystal X-ray diffraction studies. In addition, theoretical investigations provided valuable insights into their electronic structures and bonding properties.

Synthesis and Ligand Properties of Chelating Bis(N-heterocyclic carbene)-Stabilized Bis(phosphinidenes).

NHC-phosphinidene (NHCP) adducts are an emerging class of ligands with proven binding ability for main group and transition metal elements. They possess electron-rich P atoms with two lone pairs (LPs) of electrons, making them interesting platforms for the formation of multimetallic complexes. We describe herein a modular, high-yielding synthesis of bis(NHCP)s, starting from alkylidene-bridged bis(NHC)s ((IMe)2CnH2n; n = 1,3) and triphosphirane (PDip)3 (Dip = 2,6-iPr2C6H3) as phosphinidene transfer reagent. The coordination chemistry of [{DipP(IMe)}2CH2], 1, was studied in detail, and complexes [1·FeBr2] and [1·Rh(cod)]Cl were prepared, showing that the ligand has a flexible bite angle. The dicarbonyl complex [1·Rh(CO)2]Cl, with an average value for the CO stretching frequency of 2029 cm-1, indicates a strongly donating ligand when compared to related complexes. The binding ability of the remaining two phosphorus LPs was demonstrated with AuCl(SMe2), giving the heterotrimetallic complex [1·(AuCl)2·Rh(cod)]Cl. Moreover, [1·Rh(cod)]X (X- = Cl, B(3,5-(CF3)2-C6H3)4) was tested in the catalytic hydrogenation of methyl-Z-α-acetamidocinnamate (MAC) and dimethyl itaconate (ItMe2), revealing that the chloride complex was inactive, while the BArF complex demonstrated moderate activity. Additionally, [1·Rh(cod)]Cl was shown to be moderately air- and moisture-stable, slowly decomposing to the corresponding NHC-stabilized bis-dioxophosphorane, which was independently synthesized by treating the free ligand with dry O2.

A Planar Nickelaspiropentane Complex with Magnesium-Based Metalloligands: Synthesis, Structure, and Synergistic Dihydrogen Activation.

The nature of transition-metal-olefin bonding has been explained by the Dewar-Chatt-Duncanson model within a continuum of two extremes, namely, a π-complex and a metallacyclopropane. The textbook rule suggests that a low-spin late-transition-metal-ethylene complex more likely forms a π-complex rather than a metallacyclopropane. Herein, we report a low-spin late-transition-metal-bis-ethylene complex forming an unprecedented planar metalla-bis-cyclopropane structure with magnesium-based metalloligands. Treatment of LMgEt (L = [(DippNCMe)2CH]-, Dipp = 2,6-iPr2C6H3) with Ni(cod)2 (cod = 1,5-cyclooctadiene) formed the heterotrimetallic complex (LMg)2Ni(C2H4)2, which features a linear Mg-Ni-Mg linkage and a planar coordination geometry at the nickel center. Both structural features and computational studies strongly supported the Ni(C2H4)2 moiety as a nickelaspiropentane. The exposure of (LMg)2Ni(C2H4)2 to 1 bar H2 at room temperature produced a four-hydride-bridged complex (LMg)2Ni(μ-H)4. The profile of H2 activation was elucidated by density functional theory calculations, which indicated a novel Mg/Ni cooperative activation mechanism with no oxidation occurring at the metal center, differing from the prevailing mono-metal-based redox mechanism. Moreover, the heterotrimetallic complex (LMg)2Ni(C2H4)2 catalyzed the hydrogenation of a wide range of unsaturated substrates under mild conditions.

Lithium, Magnesium, and Zinc Centers N,N′-Chelated by an Amine–Amide Hybrid Ligand

The synthesis and structure of lithium, magnesium, and zinc complexes N,N'-chelated by a hybrid amine-amido ligand ([2-(Me2NCH2)C6H4NR]-, abbreviated as LNR, where R = H, SiMe3, or Bn) are reported. The reaction of the least sterically demanding LNH with various magnesium sources gives the hexameric imide [LNMg]6 (4) by the elimination of n-butane from LNHMgnBu (2) or by the reaction of LNHLi (1) with MeMgBr. [LNH]2Mg (3) is obtained through the addition of 0.5 equiv of nBu2Mg or Mg[N(SiMe3)2]2 to LNH2 and with 1 equiv of nBu2Mg reacting to 2. Both LNHMgN(SiMe3)2 (6) and isostructural LNHZnN(SiMe3)2 (16) have been prepared using two different approaches: monodeprotonation of LNH2 by Zn/Mg[N(SiMe3)2]2 in a 1:1 ratio or ligand substitution of 2 or LNHZnEt (12) by 0.5 equiv of Sn[N(SiMe3)2]2. The reactions of 2 or 3 with 1 provide the heterotrimetallic complex [LNH]4Li2Mg (5). Benzyl- or trimethylsilyl-substituted anilines [LN(SiMe3)H (7) and LN(Bn)H (8)] with 0.5 equiv of nBu2Mg allow the formation of homoleptic bis(amides) of the [LN(R)]2Mg type (10 and 11). Nevertheless, only the silylated secondary amine 7 is able to provide the heteroleptic n-butylmagnesium amide LN(SiMe3)MgnBu (9) upon reaction with an equimolar amount of nBu2Mg. Similarly, 12, [LNH]2Zn (13), LN(R)ZnEt (17 and 18), and [LN(R)]2Zn [R = SiMe3 (19) and Bn (20)] were prepared by the monodeprotonation of LNH2 or LN(R)H using Et2Zn in the corresponding stoichiometric ratio. LNHZnI was prepared by the nucleophilic substitution of an ethyl chain in 12 by molecular iodine. A heterometallic complex, [LNH]4Li2Zn (14), analogous to 5 was prepared from 12 or 13 with 1 or 2 equiv of 1, respectively.

Synthesis and Reactivity of Triangular Heterometallic Complexes Containing Zn-Zn Bond.

This work provides a facile access to a series of triangular [Zn2M] (M = group 10 and 11 metals) clusters. Treatment of Zn-Zn-bonded compounds [LZn-ZnL] (L = CH3C(2,6-iPr2C6H3N)CHC(CH3)(NCH2CH2PR2); R = Ph, iPr) with zero-valent transition-metal reagents selectively afforded the corresponding triangular clusters [Zn2M], where M = Ni(0), Pd(0), and Pt(0). Notably, the isoelectronic triangular clusters [Zn2M]+, where M = Ag(I) and Cu(I), could also be obtained by reactions of [LZn-ZnL] with AgOTf and CuOTf, respectively. The [Zn2Ag]+ complex containing elusive Zn-Ag bonds was investigated by density functional theory analysis, showing a 3c-2e bonding feature in the metallic ring. The electrochemical behaviors of [Zn2M] complexes were examined and revealed the donation of electron density from the Zn-Zn σ-bond to the metal centers. Reaction of the [Zn2Ni] complex with isocyanide gave heterometallic species by coordination of isocyanide to the nickel center, keeping the trimetallic ring core structure intact. In contrast, the Zn-Zn bond was rapidly cleaved upon treatment of the [Zn2Ni] complex with dihydrogen or phenyl acetylene, generating the hydride- or acetylide-bridged heterotrimetallic complex.

Nickel(0)-Induced β-H Elimination of Magnesium Alkyls: Formation and Reactivity of Heterometallic Hydrides.

We report the synthesis and reactivity of heterometallic Mg-Ni complexes with bridging hydrides. Treatment of magnesium monoalkyl complexes, which are supported by a tridentate β-diketiminato ligand bearing a pendent phosphine group, with nickel(0) reagent Ni(COD)2 (COD: 1,5-cyclooctadiene) at a molar ratio of 2:1 resulted in the formation of a heterotrimetallic hydride-bridged [Mg-Ni-Mg] complex via facile elimination of the corresponding alkenes. A heterobimetallic hydride-bridged [Mg-Ni] complex served as an intermediate species for the formation of the [Mg-Ni-Mg] complex. Computational studies revealed that the reaction was initiated by coordination of nickel to magnesium followed by an alkyl group transfer. β-H elimination at the nickel center subsequently occurred to give the heterometallic hydride-bridged complex. Density functional theory analysis also highlighted a three-center two-electron interaction for the Mg-H-Ni unit. The hydride-bridged [Mg-Ni-Mg] complex showed diverse reactivity toward unsaturated small molecules. For instance, reactions with isocyanides provided heterometallic species by coordination of isocyanides to the nickel center, with no subsequent reduction detected. Isocyanides could also be dissociated at 80 °C. In contrast, hydromagnesiation occurred upon treatment of the heterotrimetallic hydride with carbodiimides, affording C3-symmetric complexes with three heteroleptic magnesium mixed β-diketiminate/amidinate moieties. The hydride-bridged heterotrimetallic complex underwent dehydrogenation reaction with phenyl acetylene to produce an acetylide-bridged [Mg-Ni-Mg] complex.

A luminescent europium hairpin for DNA photosensing in the visible, based on trimetallic bis-intercalators

Luminescence monitoring of DNA intercalator complexes is important for assessing their localisation and targeting: We report herein a luminescent hetero-trimetallic complex with europium as a luminescent reporter and two attached platinum acetylide terpyridyl units as the DNA recognition units. The ligand, based on a bisamide derivative of diethylenetriaminepentaacetic acid functionalized with two ethynyl groups, provides a backbone to anchor two platinum terpyridyl units, Pt-tpy, leading to the hairpin-shaped heterometallic complex 1. We also prepared a related mono-nuclear platinum complex 2 to compare its intercalation properties with 1. Linear dichroism, UV–visible and melting experiments show the ability of both complexes to interact with calf thymus DNA, with linear dichroism confirming intercalation and demonstrating the expected greater DNA stiffening by the bis-intercalator 1. Importantly, the tri-metallic complex 1 shows a three-fold enhancement in europium luminescence upon addition of calf thymus DNA; other mono-intercalator lanthanide designs have commonly shown a decrease in emission on binding. The ability of the complex to monitor DNA interactions gives the potential use as a luminescence switch in sensing experiments and highlights the design of heterometallic bis-intercalator complexes as an effective approach for DNA-responsive sensitisation of a lanthanide luminescence signal.

From Chelating to Bridging Ligands: N-Sulfonyliminoimidazolium Ylides as Precursors to Anionic N-Heterocyclic Carbene Ligands

The synthesis and investigation of a new family of anionic N-heterocyclic carbene (NHC) ligands, based on N-sulfonyliminoimidazolium ylides, is reported. Their corresponding silver complexes have been synthesized and present distinctive geometries compared to the previously reported ligands derived from the N-acyliminoimidazolium family. A comparison of the two ligand families was performed with palladium(II) allyl complexes to investigate their binding mode preference. The N-sulfonyl derived ligands were found to strongly favor bridging binding instead of chelation. This strong preference was exploited to synthesize a novel copper(I)–palladium(II) heterotrimetallic complex.

A three body problem: a genuine heterotrimetallic molecule vs. a mixture of two parent heterobimetallic molecules.

This work raises a fundamental question about the "real" structure of molecular compounds containing three different metals: whether they consist of genuine heterotrimetallic species or of a mixture of parent heterobimetallic species. Heterotrimetallic complex Li2CoNi(tbaoac)6 (1, tbaoac = tert-butyl acetoacetate) has been designed based on the model tetranuclear structure featuring two transition metal sites in order to be utilized as a molecular precursor for the low-temperature preparation of the LiCo0.5Ni0.5O2 battery cathode material. An investigation of the structure of 1 appeared to be very challenging, since the Co and Ni atoms have very similar atomic numbers, monoisotopic masses, and radii as well as the same oxidation state and coordination number/environment. Using a statistical analysis of heavily overlaid isotope distribution patterns of the [Li2MM'L5]+ (M/M' = Co2, Ni2, and CoNi) ions in DART mass spectra, it was concluded that the reaction product 1 contains both heterotrimetallic and bimetallic species. A structural analogue approach has been applied to obtain Li2MMg(tbaoac)6 (M = Co (2) and Ni (3)) complexes that contain lighter, diamagnetic magnesium in the place of one of the 3d transition metals. X-ray crystallography, mass spectrometry, and NMR spectroscopy unambiguously confirmed the presence of three types of molecules in the reaction mixture that reaches an equilibrium, Li2M2L6 + Li2Mg2L6 ↔ 2Li2MMgL6, upon prolonged reflux in solution. The equilibrium mixture was shown to have a nearly statistical distribution of the three molecules, and this is fully supported by the results of theoretical calculations revealing that the stabilization energies of heterotrimetallic assemblies fall exactly in between those for the parent heterobimetallic species. The LiCo0.5Ni0.5O2 quaternary oxide has been obtained in its phase-pure form by thermal decomposition of heterometallic precursor 1 at temperatures as low as 450 °C. Its chemical composition, structure, morphology, and transition metal distribution have been studied by X-ray and electron diffraction techniques and compositional energy-dispersive X-ray mapping with nanometer resolution. The work clearly illustrates the advantages of heterometallic single-source precursors over the corresponding multi-source precursors.

A new ligand H4Lox and its iron(III) complex as a platform for the development of heterotrimetallic complexes

The combination of multiple metal ions of different nature, in a single coordination compound, can provide a unique set of properties suitable for applications such as mimetization of the active site of enzymatic systems, development of new molecular magnetic materials and catalysts for photoinduced water splitting. Nonetheless, the preparation of heteromultimetallic complexes, in a controlled way, is a challenging task. In this work, we present a new ligand, H4Lox, designed as a platform for the synthesis of heterotrimetallic complexes. From H4Lox and its precursor H2L, two mononuclear iron(III) complexes, [Fe(L)]NO3·MeOH·2H2O (1) [Fe(H2Lox)]NO3·XH2O (2) were synthesized and fully characterized. The structure of 2 revealed a N2O2 vacant coordination site comprised by two phenolate oxygen atoms and two oxime nitrogen atoms. DFT calculations and ESI-MS data demonstrate that complex 2 can accommodate two additional metal ions, in a stable heterotrimetallic complex. The effect of the ortho substituents of the phenolate groups (CHO and CNOH) in the electronic states of 1 and 2, respectively, was evaluated by UV–Vis spectroscopy, cyclic voltammetry and DFT calculations. A free energy correlation was found between the calculated electrophilicity index ω and the experimental half wave potentials of 1, 2 and their analogous complex [Fe(bbpen-Me)]+ [33]. The electrophilicity index ω was used to estimate the FeIII/FeII redox potential of the hypothetical [FeZnCl2(Lox)Ga(tpa)]2+ complex.

Preparation, Properties, and Reactivity of (Aminoferrocenyl)(ferrocenyl)carbene(pentacarbonyl)chromium(0) as Bulky Isolobal Trimetallo‐amide

AbstractNucleophilic substitution of the ethoxy substituent in the Fischer carbene complex (ethoxy)(ferrocenyl)carbene(pentacarbonyl)chromium(0) (1) by ferrocenyl amide [Fc‐NH]– [2‐H]– gives the hetero trimetallic complex (aminoferrocenyl)(ferrocenyl)carbene (pentacarbonyl)chromium(0) (3). As the Cr(CO)5 fragment is isolobal to oxygen or sulfur 3 can be viewed as an isolobal metallo analogue to diferrocenylamide (Fc)(FcNH)C=O (4) and diferrocenylthioamide (Fc)(FcNH)C=S (5). The impact of the formal replacement of O/S by Cr(CO)5 in 3 is studied with respect to steric and electronic consequences as well as reactivity by spectroscopic, diffraction, electrochemical and theoretical methods.

Heterotrimetallic coordination polymers: {Cu(II)Ln(III)Fe(III)} chains and {Ni(II)Ln(III)Fe(III)} layers: synthesis, crystal structures, and magnetic properties.

The use of the [Fe(III) (AA)(CN)4](-) complex anion as metalloligand towards the preformed [Cu(II) (valpn)Ln(III)](3+) or [Ni(II) (valpn)Ln(III) ](3+) heterometallic complex cations (AA=2,2'-bipyridine (bipy) and 1,10-phenathroline (phen); H2 valpn=1,3-propanediyl-bis(2-iminomethylene-6-methoxyphenol)) allowed the preparation of two families of heterotrimetallic complexes: three isostructural 1D coordination polymers of general formula {[Cu(II) (valpn)Ln(III) (H2O)3 (μ-NC)2 Fe(III) (phen)(CN)2 {(μ-NC)Fe(III) (phen)(CN)3}]NO3 ⋅7 H2O}n (Ln=Gd (1), Tb (2), and Dy (3)) and the trinuclear complex [Cu(II) (valpn)La(III) (OH2 )3 (O2 NO)(μ-NC)Fe(III) (phen)(CN)3 ]⋅NO3 ⋅H2O⋅CH3 CN (4) were obtained with the [Cu(II) (valpn)Ln(III)](3+) assembling unit, whereas three isostructural heterotrimetallic 2D networks, {[Ni(II) (valpn)Ln(III) (ONO2 )2 (H2 O)(μ-NC)3 Fe(III) (bipy)(CN)]⋅2 H2 O⋅2 CH3 CN}n (Ln=Gd (5), Tb (6), and Dy (7)) resulted with the related [Ni(II) (valpn)Ln(III) ](3+) precursor. The crystal structure of compound 4 consists of discrete heterotrimetallic complex cations, [Cu(II) (valpn)La(III) (OH2)3 (O2 NO)(μ-NC)Fe(III) (phen)(CN)3 ](+), nitrate counterions, and non-coordinate water and acetonitrile molecules. The heteroleptic {Fe(III) (bipy)(CN)4} moiety in 5-7 acts as a tris-monodentate ligand towards three {Ni(II) (valpn)Ln(III)} binuclear nodes leading to heterotrimetallic 2D networks. The ferromagnetic interaction through the diphenoxo bridge in the Cu(II)-Ln(III) (1-3) and Ni(II)-Ln(III) (5-7) units, as well as through the single cyanide bridge between the Fe(III) and either Ni(II) (5-7) or Cu(II) (4) account for the overall ferromagnetic behavior observed in 1-7. DFT-type calculations were performed to substantiate the magnetic interactions in 1, 4, and 5. Interestingly, compound 6 exhibits slow relaxation of the magnetization with maxima of the out-of-phase ac signals below 4.0 K in the lack of a dc field, the values of the pre-exponential factor (τo) and energy barrier (Ea ) through the Arrhenius equation being 2.0×10(-12) s and 29.1 cm(-1), respectively. In the case of 7, the ferromagnetic interactions through the double phenoxo (Ni(II)-Dy(III)) and single cyanide (Fe(III)-Ni(II)) pathways are masked by the depopulation of the Stark levels of the Dy(III) ion, this feature most likely accounting for the continuous decrease of χMT upon cooling observed for this last compound.

Synthesis, Characterization and Electrochemistry of Some Metal Carbonyl Clusters Derived from Ferrocenylethynylpyridine

The chemical reactivity of ferrocenylethynylpyridine ligand with some metal complexes has been studied. Ligation of this ferrocenyl-functionalized pyridyl metalloligand with triosmium carbonyl cluster [Os3(CO)10(NCMe)2] via oxidative addition led to a new supramolecular heterobimetallic cluster [Os3(CO)10(μ-H){μ-NC5H3C≡C(η5-C5H4)Fe(η5-C5H5)}] 1 in good yield. Coordination of Co2(CO)8 with the alkyne functionality of 1 gave another new heterotrimetallic cluster complex [Os3(CO)10(μ-H){μ-NC5H3{C2Co2(CO)6}(η5-C5H4)Fe(η5-C5H5)}] 2 in which the molecule possesses a Co2C2 core adopting the pseudo-tetrahedral geometry having the alkyne bond lying perpendicular to the Co–Co vector. Characterization of 1 and 2 by IR and 1H NMR spectroscopies indicated that these complexes consist of an orthometalated trinuclear carbonyl cluster unit rigidly connected to a ferrocenyl unit. Electrochemical studies on 1 and 2 revealed that both of them undergo a reversible one-electron oxidation at iron followed by an irreversible oxidation of the Os3 cluster core. Another simple mononuclear zinc(II) complex [ZnCl2{(NC5H4C≡C(η5-C5H4)Fe(η5-C5H5)}2] 3 was also prepared for comparison of the electrochemical data with those of 1 and 2.

Preparation and study of an f,f,f′,f′′ covalently linked tetranuclear hetero-trimetallic complex – a europium, terbium, dysprosium triad

A heterotrimetallic tetranuclear lanthanide complex containing two dysprosium ions, a terbium ion and a europium ion has been prepared by coupling three kinetically stable complexes together using the Ugi reaction. The covalently linked trimetallic system exhibits luminescence from all the different lanthanide centres.

Three polymers based on pyridine-2,3,5,6-tetracarboxylic acid: Syntheses, crystal structures and luminescent properties

Three novel coordination polymers, {[cis-K2Zn2Mn(μ7-pdtc)2(H2O)10]·H2O}n (1), {[cis-K2Zn3(μ7-pdtc)2(H2O)10]·0.5H2O}n (2) and [trans-K2Zn3(μ5-pdtc)2(H2O)12]n (3), were synthesized by the self-assembly of potassium pyridine-2,3,5,6-tetracarboxylate (K4pdtc) with metal salts. 1 is the first Zn/Mn/K heterotrimetallic complex with H4pdtc. 1 and 2 have 3D network structures, while 3 is a 2D coordination polymer, which are due to the different bonding modes of H4pdtc with K(I) and metal(II) ions. The fluorescence spectroscopy measurements reveal that strong photo-luminescent characteristics exhibit in 1–3 in aqueous solution at room temperature.

Synthesis and Characterization of Nickel Inverse 9-Metallacrown-3, Palladium–Silver, and Dinuclear Platinum Complexes Containing Pyrazole-Functionalized NHC Ligands

Three metallacrown nickel complexes [Ni(3)(μ-OH)(L1)(3)](PF(6))(2) (1, L1 = 3-((N-methylimidazolylidenyl)methyl)-5-methylpyrazolate), [Ni(3)(μ-OH)(L2)(3)](PF(6))(2) (2, L2 = 3-((N-mesitylimidazolylidenyl)methyl)-5-methylpyrazolate), and [Ni(3)(μ-OH)(L3)(3)](PF(6))(2) (3, L3 = 3-((N-pyrimidin-2-ylimidazolylidenyl)methyl)-5-methylpyrazolate) were obtained by the reactions of corresponding silver-NHC complexes with Raney nickel powder at 45 °C. The same reaction at 80 °C afforded [Ni(3)(L2)(4)](PF(6))(2) (4). The carbene-transfer reaction of the silver-carbene complex with [(η(3)-C(3)H(5))PdCl](2) yielded the heterotrimetallic complex [AgPd(2)(η(3)-C(3)H(5))(2)(L2)(2)](PF(6)) (5), whereas the carbene-transfer reaction with Pt(cod)Cl(2) gave [Pt(2)(L3)(2)](PF(6))(2) (6). All of these complexes have been fully characterized by ESI-MS, NMR spectroscopy, and elemental analysis. The molecular structures of 1-6 were also studied by X-ray diffraction analysis. In 1-3, three nickel centers are bridged together by three pyrazole-NHC ligands and a hydroxide group, forming a 9-metallacrown-3 topology. Complex 4 is paramagnetic, consisting of two square-planar nickel(II) ions and one tetrahedral nickel ion in which three Ni ions are bridged by four pyrazolate units. In the mixed Pd-Ag complex 5, two palladium and one silver centers are bridged by two pyrazole-NHC ligands. Complex 5 showed good catalytic activity in the Sonogashira coupling reaction of aryl bromides and phenylacetylene under mild conditions typically catalyzed by Pd-Cu systems.

Synthesis and crystal structure of one-dimensional heterotrimetallic coordination polymer {[(Dipic)2Cu]4 · Mg(H2O)2Na4(H2O)14} n · nNa2(H2O)10 · 2nCH3OH

A novel heterotrimetallic complex {[(Dipic)2Cu]4 · Mg(H2O)2Na4(H2O)14n · nNa2(H2O)10 · 2nCH3OH (H2Dipic = pyridine-2,6-dicarboxylic acid) has been synthesized and structurally determined by X-ray diffraction method. The compound crystallizes in the triclinic system, space group P\(\bar 1\), with a = 13.5523(13), b = 14.1859(13), c = 14.3213(14) A, α = 62.6160(10)°, β = 68.2540(10)°, γ = 89.7110(10)°, V = 2224.7(4)A3, F(000) = 1144, Mr = 2237.70, Z = 1, ρc = 1.670 g cm−3, μ = 1.095 mm−1, final R = 0.0507, wR = 0.1418 for 8042 independent reflections with Rint = 0.0228. According to the structure determination, the complex is composed of novel one-dimensional (1D) alternating chains, dinuclear Na(I) units, and lattice methanol molecules. The infinite 1D chain structure is built up with many of polymeric [(Dipic)2Cu]4 · Mg(H2O)2Na4(H2O)14 units, which consists of four six-coordinated Cu2+ ions, one six-coordinated Mg2+ ion, two five-coordinated Na+ ions, and two six-coordinated Na+ ions. The 1D alternating chains are linked with another dinuclear Na(I) units by extensive hydrogen bonds to form a three-dimensional (3D) supramolecular structure in which uncoordinated methanol molecules act as space filling particles.

Direct synthesis and crystal structure of a new pentanuclear heterotrimetallic Cu/Co/Ni complex with 2-(dimethylamino)ethanol. Discussion of possible “butterfly-like” molecular structure types

The pentanuclear heterotrimetallic complex [Cu2CoNi2(Me2Ea)6Cl4] (1) has been prepared in a one-pot reaction of zerovalent copper with cobalt and nickel chlorides in an acetonitrile solution of 2-(dimethylamino)ethanol (HMe2Ea) in open air. The crystal structure displays a rare planar arrangement of the metal atoms. The possible pentanuclear molecular structure types corresponding to the planar and non-planar “butterfly-like” arrangements, as well as their derivatives, are analyzed and their statistical abundance is discussed. The thermogravimetric behaviour of 1 is investigated and compared with literature examples.

First 3D heterotrimetallic Mn(II)–Cu(II)–K(I) polymer and three 3D Cu(II)/Mn(II) open network based on pyridine-2,3,5,6-tetracarboxylic acid

Four novel 3D coordination polymers, {[K3Cu2(H0.5pdtc)2 (H2O)6]·(H2O)2}n (1), {[trans-K2Mn3(pdtc)2 (H2O)11]·H2O}n (2), {[trans-K2Mn3(pdtc)2 (H2O)10]·H2O}n (3) and {[cis-K2Cu2Mn(pdtc)2 (H2O)10]·H2O}n (4), were synthesized by the self-assembly of potassium pyridine-2,3,5,6-tetracarboxylate (K4pdtc) with metal salts. All of them contain infinite 1D stepwise chain. Notably, 2–4 have 2D network structures depending on the trans- and cis- hexacoordinated Mn(II) acting as connecters between the chains. Then, they further assemble into 3D or twin-plane structures by K(I) ions. 4 is the first Cu/Mn/K heterotrimetallic complex with H4pdtc. The (H2O)6 clusters in 1 arranged stepwise along the complex chains owing to the host chains' template effect. The variable–temperature magnetic measurements reveal that weak antiferromagnetic interactions exist in complexes 1 and 4.

A Pentanuclear Cu/Co/Ni Complex with 2‐(Dimethylamino)ethanol – Observation of a Rare Molecular Structure Type and Its Place in General Structural Types: An Analysis of the Cambridge Structural Database

AbstractHeterotrimetallic complex [CuII2CoIINiII2(Me2Ea)5Cl5(H2O)]·CH3CN·H2O has been prepared in a one‐pot reaction of zero‐valent copper with cobalt and nickel chlorides in an acetonitrile solution of 2‐(dimethylamino)ethanol (HMe2Ea) in the open air. The metal stoichiometry obtained by atomic absorption analysis was further confirmed by single‐crystal X‐ray diffraction investigations. The pentanuclear molecule is formed by a previously unknown combination of incomplete cube M3(μ3‐X)(μ‐X)3 and triangle bipyramidal M3(μ3‐X)2(μ‐X)2 fragments, resulting in a zigzag arrangement of metal centers within one molecule. This type of arrangement is very uncommon for pentanuclear complexes and in particular for complexes with an odd number of metal centers. A search of the Cambridge Structural Database showed that the number of coordination compounds possessing an even number of metals is significantly greater than those containing an odd number. Possible reasons for such a distribution, as well as the synthetic and structural features of the presented compound, are discussed.(© Wiley‐VCH Verlag GmbH & Co. KGaA, 69451 Weinheim, Germany, 2009)