Self-Assembly of a Redox Active,Metallosupramolecular [Pd3L6]6+ Complex Using a Rotationally Flexible Ferrocene Ligand

A new ferrocene-containing [Pd₃( L_4EFc )₆]⁶⁺(X⁻)₆ ( C ⋅ BF₄ and C ⋅ SbF₆ where X=BF₄⁻ or SbF₆⁻) self-assembled double-walled triangle has been synthesized from the known, rotationally flexible, 1,1′-bis(4-pyridylethynyl)ferrocene ligand ( L_4EFc ), and characterized by ¹H, ¹³C and diffusion ordered (DOSY) NMR spectroscopies, high-resolution electrospray ionization mass spectrometry (HR−ESI−MS), X-ray crystallography and cyclic voltammetry (CV). The molecular structures confirmed that double-walled triangle cage systems ( C ⋅ BF₄ and C ⋅ SbF₆ ) were generated. C ⋅ BF₄ was shown to interact with the anionic guest, p-toluenesulfonate. CV experiments revealed that the triangles were redox active, however addition of the guest did not influence the redox potentials.     

Wide‐Ranging Host Capability of a PdII‐Linked M2L4 Molecular Capsule with an Anthracene Shell

This article reports that an M₂L₄ molecular capsule is capable of encapsulating various neutral molecules in quantitative yields. The capsule was obtained as a single product by mixing a small number of components; two Pd^II ions and four bent bispyridine ligands containing two anthracene panels. Detailed studies of the host capability of the Pd^II‐linked capsule revealed that spherical (e.g., paracyclophane, adamantanes, and fullerene C₆₀), planar (e.g., pyrenes and triphenylene), and bowl‐shaped molecules (e.g., corannulene) were encapsulated in the large spherical cavity, giving rise to 1:1 and 1:2 host–guest complexes, respectively. The volume of the encapsulated guest molecules ranged from 190 to 490 ų. Within the capsule, the planar guests adopt a stacked‐dimer structure and the bowl‐shaped guests formed an unprecedented concave‐to‐concave capsular structure, which are fully shielded by the anthracene shell. Competitive binding experiments of the capsule with a set of the planar guests established a preferential binding series for pyrenes≈phenanthrene>triphenylene. Furthermore, the capsule showed the selective formation of an unusual ternary complex in the case of triphenylene and corannulene.     

Crystal and molecular structure and vibrational spectra of 2,6-bis(diphenylphosphorylmethyl)-4-methylphenol and its complex with cerium(III) nitrate

The structure of 2,6-bis(diphenylphosphorylmethyl)-4-methylphenol 2,6-[Ph₂P(O)CH₂]₂-4-MeC₆H₂OH(L¹) and its 1: 1 complex with cerium(III) nitrate were studied by X-ray diffraction. A rather strong intramolecular hydrogen bond P=O…H-O (O…O, 2.646(1) Å) exists in the L¹ molecules. In the crystal, the molecules are combined into centrosymmetric dimers through the stacking interaction between the central phenol rings; the distance between the ring planes is 3.39 Å. In the complex molecule, [Ce(L¹)(NO₃)₃ · Me₂C(O)], the neutral ligand L¹ is tridentate and the three nitrate ions are bidentate, and the tenth coordination site is occupied by acetone oxygen. No intramolecular H-bonds are present. In the crystal, the complex molecules are combined into centrosymmetric dimers through intermolecular hydrogen bonds O-H…O-NO₂ (O…O, 2.713(8) Å). The vibrational (IR, Raman) spectra of the ligand and the complex were studied and the principal bands were assigned. According to IR spectroscopy, the P=O…H-O intramolecular hydrogen bond is retained in both the ligand and the complex molecules.     

A Tray‐Shaped,PdII‐Clipped Au3 Complex as a Scaffold for the Modular Assembly of [3×n] Au Ion Clusters

A tray‐shaped Pd^II₃Au^I₃ complex ( 1 ) is prepared from 3,5‐bis(3‐pyridyl)pyrazole by means of tricyclization with Au^I followed by Pd^II clipping. Tray 1 is an efficient scaffold for the modular assembly of [3×n] Au^I clusters. Treatment of 1 with the Au^I₃ tricyclic guest 2 in H₂O/CH₃CN (7:3) or H₂O results in the selective formation of a [3×2] cluster ( 1 ⋅ 2 ) or a [3×3] cluster ( 1 ⋅ 2 ⋅ 1 ), respectively. Upon subsequent addition of Ag^I ions, these complexes are converted to an unprecedented Au₃–Au₃–Ag–Au₃–Au₃ metal ion cluster.     

Zinc(II)–Organic Framework Films with Thermochromic and Solvatochromic Applications

Multiple-stimuli-responsive photoluminescence films based on a Zn^II–organic framework, {[Zn₂(Htpim)(3,4-pydc)₂] ⋅ 4 DMF ⋅ 4 H₂O}_n ( 1 , Htpim=2,4,5-tri(4-pyridyl)imidazole, 3,4-H₂pydc=3,4-pyridinedicarboxylic acid), were fabricated. This compound consisted of a 2D corrugated layer, {Zn(3,4-pydc)}_n, which was further pillared using a Y-shaped pillar N-donor ligand (Htpim) to form a 3D-pillared-layer framework with 1D open channels. The rectangular channels in the as-synthesized compound are fully occupied by guest DMF and H₂O molecules. The framework exhibits instant and reversible thermochromic properties corresponding to the removal of different H₂O and DMF guest molecules as temperature increases. The pale-yellow crystal undergoes significant redshifting to a greenish emission centered at 530 nm. Compound 1 also showed remarkable solvatochromic effects in the presence of various organic solvents without affecting its structural integrity. In addition, polycrystalline MOF films were grown on an α-Al₂O₃ support for switchable and fast-response thermochromic and solvatochromic sensors.     

Adsorption behaviour of a CdII–triazole MOF for butan‐2‐one in a single‐crystal‐to‐single‐crystal (SCSC) fashion: the role of hydrogen bonding and C—H…π interactions

The adsorption behaviour of the Cd^II–MOF {[Cd(L)₂(ClO₄)₂]·H₂O ( 1 ), where L is 4‐amino‐3,5‐bis[3‐(pyridin‐4‐yl)phenyl]‐1,2,4‐triazole, for butan‐2‐one was investigated in a single‐crystal‐to‐single‐crystal (SCSC) fashion. A new host–guest system that encapsulated butan‐2‐one molecules, namely poly[[bis{μ₃‐4‐amino‐3,5‐bis[3‐(pyridin‐4‐yl)phenyl]‐1,2,4‐triazole}cadmium(II)] bis(perchlorate) butanone sesquisolvate], {[Cd(C₂₄H₁₈N₆)₂](ClO₄)₂·1.5C₄H₈O}_n, denoted C₄H₈O@Cd‐MOF ( 2 ), was obtained via an SCSC transformation. MOF 2 crystallizes in the tetragonal space group P4₃2₁2. The specific binding sites for butan‐2‐one in the host were determined by single‐crystal X‐ray diffraction studies. N—H…O and C—H…O hydrogen‐bonding interactions and C—H…π interactions between the framework, ClO₄^? anions and guest molecules co‐operatively bind 1.5 butan‐2‐one molecules within the channels. The adsorption behaviour was further evidenced by ¹H NMR, IR, TGA and powder X‐ray diffraction experiments, which are consistent with the single‐crystal X‐ray analysis. A ¹H NMR experiment demonstrates that the supramolecular interactions between the framework, ClO₄^? anions and guest molecules in MOF 2 lead to a high butan‐2‐one uptake in the channel.     

Synthesis, vibrational spectra, and crystal and molecular structure of copper 1,5-bis[2-(dihydroxyphosphinyl)phenoxy]-3-oxapentane dihydrate [Cu(H2L2)(H2O)2]

A new complex Cu(H₂L²)(H₂O)₂] (I), where H₄L² is 1,5-bis[2-(dihydroxyphosphinyl)phenoxy]-3-oxapentane, has been synthesized and characterized. Its molecular and crystal structure has been determined by X-ray crystallography and vibrational spectroscopy. In mononuclear complex I, the copper(II) cation is in a distorted square-planar environment of two water oxygen atoms and two oxygen atoms of the chelating dianion (H₂L²)^2?. The crystals are orthorhombic, space group Cmc2₁, a = 25.909(5) ?, b = 9.1500(18) ?, c = 8.5600(17) ?, V = 2029.3(7) ?³, Z = 4, ??_calc = 1.688 g cm^?3, ?? = 1.292 cm^?1; 3107 measured reflections, 1174 reflections with I > 2.0??(I), R _int = 0.0600, GOOF = 1.413, R ₁ (I > 2??(I)) = 0.0812, wR ₂ (I > 2??(I)) = 0.2145.     

The Effect of Guest Metal Ions on the Reduction Potentials of Uranium(VI) Complexes: Experimental and Theoretical Investigations

Two mononuclear uranyl complexes, [UO₂L¹] ( 1 ) and [UO₂L²] ⋅ 0.5 CH₃CN ⋅ 0.25 CH₃OH ( 2 ), have been synthesized from two multidentate N₃O₄ donor ligands, N,N′-bis(5-methoxysalicylidene)diethylenetriamine (H₂L¹) and N,N′-bis(3-methoxysalicylidene)diethylenetriamine (H₂L²), respectively, and have been structurally characterized. Both complexes 1 and 2 showed a reversible U^VI/U^V couple at −1.571 and −1.519 V, respectively, in cyclic voltammetry. The reduction potential of the U^VI/U^V couple shifted towards more positive potential on addition of Li⁺, Na⁺, K⁺, and Ag⁺ metal ions to acetonitrile solutions of complex 2 , and the resulting potential was correlated with the Lewis acidity of the metal ions and was also justified by theoretical DFT calculations. No such shift in reduction potential was observed for complex 1 . All four bimetallic products, [UO₂L²Li_0.5](ClO₄)_0.5 ( 3 ), [UO₂L²Na(ClO₄)]₂ ( 4 ), [UO₂L²Ag(NO₃)(H₂O)] ( 5 ), and [(UO₂L²)₂K(H₂O)₂]PF₆ ( 6 ), formed on addition of the Li⁺, Na⁺, Ag⁺, and K⁺ metal ions, respectively, to acetonitrile solutions of complex 2 , were isolated in the solid state and structurally characterized by single-crystal X-ray diffraction. In all the species, the inner N₃O₂ donor set of the ligand encompasses the equatorial plane of the uranyl ion and the outer open compartment with O₂O′₂ donor sites hosts the second metal ion.     

Second-Sphere Coordination of the Tris(5, 5′-diamino-2, 2′-bipyridine)iron Complex With Arene-Carboxylate Ligands Through N-H···O Hydrogen Bonding

The tris(5, 5′-diamino-2, 2′-bipyridine)iron(II) complex [Fe(DABP)₃]²⁺ can be engaged in hydrogen-bonding interactions from the amino groups to carboxylate-containing molecules as H-bond acceptors. This so-called second-sphere coordination of the metal complex is investigated here by using benzene-1, 4-dicarboxylate (terephthalate, L¹ ), benzene-1, 3-dicarboxylate (isophthalate, L² ), biphenyl-2, 2′-dicarboxylate ( L³ ), and benzene-1, 3, 5-tricarboxylate (trimesate, L⁴ ) anions for N-H···O bonding. The second-sphere coordination of [Fe(DABP)₃]²⁺ is further complemented by water molecules of crystallization in the isolated and structurally elucidated compounds of [Fe(DABP)₃]( L¹ )·5H₂O, [Fe(DABP)₃]( L² )·8H₂O, [Fe(DABP)₃]( L³ )·12.5H₂O, and [Fe(DABP)₃]₃( L⁴ )₂·20H₂O. The hydrogen-bonding between [Fe(DABP)₃]²⁺ and the dicarboxylate anions ( L¹-L³ ) decreases from a three-dimensional supramolecular network (with L¹ ) to discrete units (with L² and L³ ) with the increasing number of crystal water molecules. The tricarboxylate ligand L⁴ is capable of capping the triangular face formed by the three amino groups in [Fe(DABP)₃]²⁺. The solid-state structures of DABP·2H₂O and 5, 5′-bis(ethoxycarbonylamino)-2, 2′-bipyridine (BEBP) are reported.     

From Specific γ-CD/[Nb6Cl12(H2O)6]2+ Recognition to Biological Activity Tuning

Specific molecular recognition of γ-cyclodextrin (γ-CD) by the cationic hexanuclear niobium [Nb₆Cl₁₂(H₂O)₆]²⁺ cluster complex in aqueous solutions results in a 1:1 supramolecular assembly {[Nb₆Cl₁₂(H₂O)₆]@γ-CD}²⁺. NMR spectroscopy, isothermal titration calorimetry (ITC), and ESI-MS were used to study the interaction between the inorganic cluster and the organic macrocycle. Such molecular association affects the biological activity of [Nb₆Cl₁₂(H₂O)₆]²⁺, decreasing its cytotoxicity despite enhanced cellular uptake. The 1:1 stoichiometry is maintained in solution over a large window of the reagents’ ratio, but crystallization by slow evaporation produces a 1:2 host–guest complex [Nb₆Cl₁₂(H₂O)₆@(γ-CD)₂]Cl₂ ⋅ 20 H₂O featuring the cluster encapsulated between two molecules of γ-CD. The 1:2 complex was characterized by XRD, elemental analysis, IR spectroscopy, and thermogravimetric analysis (TGA). Quantum chemical calculations were performed to model host–guest interaction.     

A New Approach for the Voltammetric Determination of Amoxicillin in the Dosage Form Using Azo Coupling Reaction with Sulphanilamide

The novel method of amoxicillin (AM) determination has been developed using single-sweep polarography. The proposed method is based on the obtaining of yellow coloured azo compound due to azo coupling reaction of previous diazotized sulphanilamide (SA) (in the medium of 0.6 M hydrochloric acid) with amoxicillin at pH=9.0 with the further reduction of the formed analytical form on a dropping mercury electrode. Voltammetric determination of amoxicillin is carried out due to the reduction peak of azo group of the obtained azo compound in the presence of 0.05 mol ⋅ L⁻¹ Na₂B₄O₇ as a background electrolyte at the potential E_c^p2=−0.55 V and potential sweep rate of 2.5 V ⋅ s⁻¹. The developed voltammetric method has two linear ranges of the determined concentrations (0.05–2.0) ⋅ 10⁻⁵ mol ⋅ L⁻¹ and (0.2–1.0) ⋅ 10⁻⁴ mol ⋅ L⁻¹ and the high sensitivity: LOD without the removing of unreacted sodium nitrite is 1.1 ⋅ 10⁻⁶ mol ⋅ L⁻¹, and 7.2 ⋅ 10⁻⁷ mol ⋅ L⁻¹, when NaNO₂ excess is removed using urea. The developed voltammetric technique of AM determination has been approved during the analyses of tablets and oral suspension.     

Turn‐On Fluorescence and Unprecedented Encapsulation of Large Aromatic Molecules within a Manganese(II)–Triazole Metal–Organic Confined Space

For the purpose of investigating the coordination behavior of sterically congested alkenes and exploring the possibility of cofacial complexation in the polycyclic aromatic system for the formation of extended polymeric networks, a new tetradentate ligand, 1,1,2,2‐tetrakis[4‐(1H‐1,2,4‐triazol‐1‐yl)phenyl]ethylene (TTPE), has been designed and synthesized. By using TTPE as a building block with regard to the self‐assembly with MnCl₂ ? 4 H₂O, a novel two‐dimensional coordination framework {[Mn(TTPE)Cl₂] ? 4 CHCl₃}_n ( 1 ) can be isolated. Anion‐exchange and organic‐group‐functionalized aromatic guest TTPE‐loaded host–guest complex experimental results indicate that coordinated Cl^? anions in the 2D framework of 1 can be completely replaced with dissociative ClO₄^? groups in an irreversible single‐crystal‐to‐single‐crystal transformation fashion, as evidenced by the anion‐exchange products of {[Mn(TTPE)(H₂O)₂](ClO₄)₂ ? 0.5 TTPE ? 5.25 H₂O}_n ( 2 ). Interestingly, TTPE, acting as an organic template, was encapsulated in the confined space of the 2D grid of 2 . To the best of our knowledge, such large organic molecules encapsulated in the reactive organic‐group‐functionalized aromatic‐guest‐loaded host–guest complex are unprecedented up to now. Luminescence measurements illustrate that 1 and 2 represent novel examples of sensing materials based on triazole derivatives. Further, 2 has been demonstrated by tuning the fluorescence response of porous metal–organic frameworks as a function of adsorbed small analytes.     

Noncovalent Modulation of Chemoselectivity in the Gas Phase Leads to a Switchover in Reaction Type from Heterolytic to Homolytic to Electrocyclic Cleavage

In the gas phase, thermal activation of supramolecular assemblies such as host–guest complexes leads commonly to noncovalent dissociation into the individual components. Chemical reactions, for example of encapsulated guest molecules, are only found in exceptional cases. As observed by mass spectrometry, when 1-amino-methyl-2,3-diazabicyclo[2.2.2]oct-2-ene (DBOA) is complexed by the macrocycle β-cyclodextrin, its protonated complex undergoes collision-induced dissociation into its components, the conventional reaction pathway. Inside the macrocyclic cavity of cucurbit[7]uril (CB7), a competitive chemical reaction of monoprotonated DBOA takes place upon thermal activation, namely a stepwise homolytic covalent bond cleavage with the elimination of N₂, while the doubly protonated CB7⋅DBOA complex undergoes an inner-phase elimination of ethylene, a concerted, electrocyclic ring-opening reaction. These chemical reaction pathways stand in contrast to the gas-phase chemistry of uncomplexed monoprotonated DBOA, for which an elimination of NH₃ predominates upon collision-induced activation, as a heterolytic bond cleavage reaction. The combined results, which can be rationalized in terms of organic-chemical reaction mechanisms and density-function theoretical calculations, demonstrate that chemical reactions in the gas phase can be steered chemoselectively through noncovalent interactions.     

In Situ Metal-Assisted Ligand Modification Induces Mn4 Cluster-to-Cluster Transformation: A Crystallography,Mass Spectrometry,and DFT Study

Dehydration of (S,S)-1,2-bis(1H-benzo[d]imidazol-2-yl)ethane-1,2-diol (H₄L) to (Z)-1,2-bis(1H-benzo[d]imidazol-2-yl)ethenol) (H₃L′) was found to be metal-assisted, occurs under solvothermal conditions (H₂O/CH₃OH), and leads to [Mn^II₄(H₃L)₄Cl₂]Cl₂ ⋅ 5 H₂O ⋅ 5 CH₃OH ( Mn₄L₄ ) and [Mn^II₄(H₂L′)₆(μ₃-OH)]Cl ⋅ 4 CH₃OH ⋅ H₂O ( Mn₄L′₆ ), respectively. Their structures were determined by single-crystal XRD. Extensive ESI-MS studies on solutions and solids of the reaction led to the proposal consisting of an initial stepwise assembly of Mn₄L₄ from the reactants via [MnL] and [Mn₂L₂] below 80 °C, and then disassembly to [MnL] and [MnL₂] followed by ligand modification before reassembly to Mn₄L′₆ via [MnL′], [MnL′₂], and [Mn₂L′₃] with increasing solvothermal temperature up to 140 °C. Identification of intermediates [Mn₄L_xL′_6−x] (x=5, 4, 3, 2, 1) in the process further suggested an assembly/disassembly/in situ reaction/reassembly transformation mechanism. These results not only reveal that multiple phase transformations are possible even though they were not realized in the crystalline state, but also help to better understand the complex transformation process between coordination clusters during “black-box” reactions.     

Effect of Bulkiness on Reversible Substitution Reaction at MnII Center with Concomitant Movement of the Lattice DMF: Observation through Single‐Crystal to Single‐Crystal Fashion

The porous coordination polymer ({[Mn(L)H₂O](H₂O)_1.5(dmf)}_n, 1 ) (DMF=N,N‐dimethylformamide) exhibits variety of substitution reactions along with movement of lattice DMF molecule depending upon bulkiness of the external guest molecules. If pyridine or 4‐picoline is used as a guest, both lattice and coordinated solvent molecules are simultaneously substituted (complexes 6 and 7 , respectively). If a bulky guest like aniline is used, a partial substitution at the metal centers and full substitution at the channels takes place (complex 8 ). If the guest is 2‐picoline (by varying the position of bulky methyl group with respect to donor N atom), one Mn^II center is substituted by 2‐picoline, whereas the remaining center is substituted by a DMF molecule that migrates from the channel to the metal center (complex 9 ). Here, the lattice solvent molecules are substituted by 2‐picoline molecules. For the case of other bulky guests like benzonitrile or 2,6‐lutidine, both the metal centers are substituted by two DMF molecules, again migrating from the channel, and the lattice solvent molecules are substituted by these guest molecules (complex 10 and 11 , respectively). A preferential substitution of pyridine over benzonitrile (complex 12 ) at the metal centers is observed only when the molar ratio of PhCN:Py is 95:5 or less. For the case of an aliphatic dimethylaminoacetonitrile guest, the metal centers remain unsubstituted (complex 13 ); rather substitutions of the lattice solvents by the guest molecules take place. All these phenomena are observed through single crystal to single crystal (SC–SC) phenomena.     

Organosulfonate-Modulated Spin-Crossover Behavior in Three Halogen-Functionalized Cobalt(II) Complexes

We present here the syntheses, crystal structures, and spin crossover (SCO) properties of a series of halogen-functionalized cobalt(II) complexes, [Co(Brphtpy)₂](OTf)₂ ⋅ DMF ⋅ 2H₂O ( 1 ), [Co(Brphtpy)₂](HBS)₂ ⋅ H₂O ( 2 ), [Co(Brphtpy)₂](MQ)₂ ⋅ 2MeCN ⋅ 3H₂O ( 3 ) ( Brphtpy =4′–(4-Bromophenyl)–2,2′:6′,2′′-terpyridine; OTf⁻=trifluoromethanesulfonate; HBS⁻=hydroxybenzenesulfonate dihydrate; MQ⁻=methyl orange). Variable-temperature single-crystal X-ray analyses revealed mononuclear compounds of 1 – 3 consisted of [Co(Brphtpy)₂]²⁺ SCO active units and organosulfonate anions and no structural phase transformation happened in measured high-low temperature. The packing structures of these complexes were tuned by varying organosulfonates. However, no notable supramolecular interactions can be found, in turn leading to gradual, incomplete, and non-hysteretic SCO behaviors. Interestingly, the SCO behaviors of these three complexes were significantly modified after the removal of lattice solvents. Combined structural and magnetic investigations revealed the non-cooperative supramolecular packing structures, guest internal pressure, and the small structural distortions of the SCO units should be responsible for the worse SCO properties of 1 – 3 . The foregoing results show that to achieve high-performance Co²⁺ SCO, both the weak interactions, internal pressure, and structural distortion should be considered during the design and construction of SCO complexes.     

Unusual Encapsulation of Two Anions in the Cavity of Neutral Macrocyclic Octalactam,Preliminary Communication

A new neutral anion receptor – macrocyclic octalactam 2 , possessing a large 36‐membered ring, was synthesized, and its unusual property of encapsulation of two Cl⁻ ions and two H₂O molecules in the cavity was confirmed by X‐ray crystallography (see Figure). The octalactam, consisting of four 2,6‐dicarbamoylpyridine and four ethylene moieties, exhibits a symmetrical, fully expanded conformation in the complex [(Cl)₂( 2 )(H₂O)₂]²⁻ (obtained as 2 ⋅2 Bu₄NCl⋅4 H₂O⋅2 CH₂Cl₂). Inside the cavity, encapsulated species – two Cl⁻ ions and two H₂O molecules – are connected to each other by H‐bonds. This kind of complex‐in‐complex system is formed by means of twenty intra‐ring H‐bonds and additionally four from the ‘outside' H₂O molecules. Considering size and symmetry, it can be stated that the planar (H₂O⋅Cl⁻)₂ dimer fits well into the cavity of octalactam 2 . The ligand has an optimal arrangement of binding sites to form H‐bonds to every corner of the dimer.     

Silver(I) complexes of triazine derivatives having stepped π–π interactions and 2D sheets

Reactions of silver(I) perchlorate and triflate with the triazine ligands 2,4,6-trimethoxy-1,3,5-triazine (L¹) and 2,4,6-triphenyl-1,3,5-triazine (L²) have provided three novel silver complexes: [Ag(L¹)₂](ClO₄) (1), [Ag(L¹)₂](CF₃SO₃) (2) and [Ag₂(L²)(CF₃SO₃)₂] (3). The crystal structures of these complexes have been determined by single-crystal X-ray diffraction. Each complex exhibits distinct coordination behavior and different frameworks. Complex 1 has a 1D stepped framework in which one crystallographically independent metal center interacts with two L¹ molecules and strong π–π interactions between the triazine planes of two L¹ molecules exist. On the other hand, complex 2 has a herringbone-like molecular packing in which the triflate ions are arranged between mononuclear complex cations. In complex 3, L² molecules are suspended between two double chains of silver triflate through the coordination to silver(I) ions to form the 2D sheet network structure. The factors that influence the crystal structure and packing are discussed.     

Cyclooctenyl complexes of palladium(II) with multidentate N-heterocycles

[Pd(cod)(cotl)]ClO₄ (cod = 1,5-cyclooctadiene, cotl = cyclooctenyl, C₈H₁₃ ^–) undergoes substitutions with multidentate N-heterocycles: 1,3-bis(benzimidazolyl)benzene (L¹), 1,3-bis(1-methylbenzimidazol-2-yl)benzene (L²), 2,6-bis(benzimidazolyl)pyridine (L³) and 2,6-bis(1-methylbenzimidazol-2-yl)pyridine (L⁴) to yield mono/binuclear complexes: [Pd(cotl)(L¹)(OClO₃)], [Pd(cotl)(L)]ClO₄ (L = L² or L³) and [Pd(cotl)₂(L⁴)](ClO₄)₂. Dihalobridged binuclear complexes [PdX(cotl)]₂ (X = Cl or Br) undergo halogen bridge cleavages with the multidentate N-heterocycles to form binuclear complexes of the type [PdX(cotl)₂L] (X = Cl or Br; L = L¹, L², L³ or L⁴). The complexes were characterized by elemental analyses, ¹H-, ¹³C-n.m.r., i.r., far-i.r. and FAB-mass spectral studies.     

Synthesis of Functionalized Heteroleptic Germylene Alkoxides

N-coordinated Ge(II) alkoxides L¹(tBuO)Ge ( 1 ), L²(tBuO)Ge ( 2 ) and [L²(OtBu)Ge ⋅ BH₃] ( 4 ) were prepared. Effect of either chelating ligands L¹ and L² or Ge→B interaction on strength of the Ge−OtBu bond was studied by insertion reaction of PhNCO. As a result, the Ge(II) carbamate L²{[(tBuO)OC](Ph)N}Ge ( 3 ) was isolated. Alcoholysis exchange reactions of 1 and 2 with substituted phenols were studied to find an easy synthetic protocol for a synthesis of functionalized Ge(II) alkoxides. Reactions yielded Ge(II) alkoxides L^1,2(2-Br−C₆H₄O)Ge ( 5 for L¹, 8 for L²), L^1,2(2-MeNH−C₆H₄O)Ge ( 6 for L¹, 9 for L²), L^1,2(2-Ph₂P−C₆H₄O)Ge ( 7 for L¹, 10 for L²), L²(2-Br-3-OH−C₆H₃O)Ge ( 11 ) and L²(2-NC₅H₄O)Ge ( 12 ) containing the additional polar groups Y (Y=Br, MeNH, PPh₂, OH or N). Finally, phosphane decorated Ge(II) alkoxides 7 and 10 were tested as suitable ligands in reactions with (COD)W(CO)₄ and BH₃. As a consequence, new complexes [(κ²- 7 )W(CO)₄] ( 13 ) and [L¹(2-Ph₂P ⋅ {BH₃}-C₆H₄O)Ge ⋅ {BH₃}] ( 14 ) were isolated. All compounds were characterized by NMR and IR spectroscopy, and compounds 3 , 4 , 9 and 11 were additionally characterized by X-ray diffraction analysis.