Organometallic Coordination Research Articles

Organoboron compounds as versatile reagents in the transition metal-catalyzed C–S, C–Se and C–Te bond formation

• Coupling reaction using organoboron compounds. • Organometallic catalysis and coordination. • Different methods for obtaining a new Carbon–Chalcogen bond. • Coupling reactions between different sources of chalcogen and organoboron reagents. Organochalcogen compounds present synthetic and biological applications of extreme relevance. The coupling reaction between boronic acids, borate anions or boronic esters with different sources of chalcogen (S, Se and Te), mediated by transition metals, is a powerful tool for the formation of functionalized diorganyl chalcogenides. By this strategy, selenides, sulfides, and tellurides with high complexity and molecular diversity can be prepared in good to excellent yields. This review covers the use of organoboron compounds as a versatile reagent for the formation of Carbon–Chalcogen bonds using different metallic catalysts (Cu, Ag, Pd, Fe, In, Rh, Ni).

Surprising Homolytic Gas Phase Co-C Bond Dissociation Energies of Organometallic Aryl-Cobinamides Reveal Notable Non-Bonded Intramolecular Interactions.

Aryl‐cobalamins are a new class of organometallic structural mimics of vitamin B12 designed as potential ‘antivitamins B12’. Here, the first cationic aryl‐cobinamides are described, which were synthesized using the newly developed diaryl‐iodonium method. The aryl‐cobinamides were obtained as pairs of organometallic coordination isomers, the stereo‐structure of which was unambiguously assigned based on homo‐ and heteronuclear NMR spectra. The availability of isomers with axial attachment of the aryl group, either at the ‘beta’ or at the ‘alpha’ face of the cobalt‐center allowed for an unprecedented comparison of the organometallic reactivity of such pairs. The homolytic gas‐phase bond dissociation energies (BDEs) of the coordination‐isomeric phenyl‐ and 4‐ethylphenyl‐cobinamides were determined by ESI‐MS threshold CID experiments, furnishing (Co−Csp2 )‐BDEs of 38.4 and 40.6 kcal mol−1, respectively, for the two β‐isomers, and the larger BDEs of 46.6 and 43.8 kcal mol−1 for the corresponding α‐isomers. Surprisingly, the observed (Co−Csp2 )‐BDEs of the Coβ‐aryl‐cobinamides were smaller than the (Co−Csp3 )‐BDE of Coβ‐methyl‐cobinamide. DFT studies and the magnitudes of the experimental (Co−Csp2 )‐BDEs revealed relevant contributions of non‐bonded interactions in aryl‐cobinamides, notably steric strain between the aryl and the cobalt‐corrin moieties and non‐bonded interactions with and among the peripheral sidechains.

Rare-Earth Metal Boroxide with Formal Triple Metal–Oxygen Orbital Interaction: Synthesis from B(C 6 F 5 ) 3 ·H 2 O and Radical-Anion Ligated Rare-Earth Metal Amides

Rare-earth metal boroxides are not only rare and of great synthetic challenge but also important theoretically due to their unrevealed bonding characteristics. In this paper, we report the synthesi...

Synthesis and identification of 1,1,3,3-tetra-[1,2-dihydro-1,5-dimethyl-2-phenyl-3-oxopyrazole]propane

Pyrazole derivatives are of practical value as analytical reagents, dyes and medicinal substances. It is known that 1,2-dihydro-1,5-dimethyl-2-phenylpyrazol-3H-one (antipyrine) and its bidentate derivatives are good analytical reagents for d-metal ions (Cd2+, Fe3+, Sc3+, Ti4+, Zn2+, Co2+, etc.). The chelating ability of bi-, tri- and tetradentate antipyrine derivatives make them promising organic ligands for the synthesis of organometallic coordination polymers. Therefore, synthesis of new tetradentate derivatives of 1,2-dihydro-1,5-dimethyl-2-phenyl-3Hpyrazole-one seems to be a highly relevant research task. The aim of this work was to synthesize and study a new substance – 1,1,3,3-tetra-[1,2-dihydro-1,5-dimethyl-2-phenyl-3-oxopyrazole]propane (tetraantipyryl-propane). A review of existing methods for the synthesis of antipyrine derivatives through condensation of 1,2-dihydro-1,5-dimethyl-2-phenyl-3H-pyrazol-3-one with aliphatic and aromatic aldehydes was carried out. A method was developed for the preparation and purification of 1,1,3,3-tetra-[1,2-dihydro-1,5-dimethyl-2-phenyl-3-oxopyrazole]propane by the reaction of electrophilic substitution of the protonated form of propandial (malonic dialdehyde) in the aromatic ring of the oxopyrazole heterocycle with a yield of 17.1%. The resulting compound is a white crystalline substance, readily soluble in organic polar and non-polar solvents, but insoluble in water. The purity of the recrystallized synthesis product was confirmed by measuring its melting point and conducting a qualitative reaction with sodium nitrite to detect an unsubstituted oxopyrazole cycle in the reaction substrate. The structure of 1,1,3,3-tetra-[1,2-dihydro-1,5-dimethyl-2-phenyl-3-oxopyrazole]propane was established by mass spectrometry and Raman spectroscopy.

Electrochemical properties of Rubpy-reduced graphene oxide synergized by ultrasonication for label-free quercetin sensing

Tuning the interfacial properties of oxygenated graphene and reduced graphene oxide (rGO) with optical/electrochemically active molecules are highly useful for sensor studies. Herein, we demonstrate the ultrasonochemical mediated simultaneous reduction of oxygenated graphene and adsorption of ruthenium bipyridine complex (Rubpy) on the planes of rGO nanosheets. Different weight percentage ratio of Rubpy was decorated on the planes of rGO by simple alteration in the sonication parameters. Intercalation of Rubpy complex influences the electron cloud of inherent graphitic carbon network and intermolecular oxygenated functional moieties on the rGO matrix. Activation of CN network derived from bipyridine ligands of organometallic coordination compound, Rubpy, on the rGO planes enable an amplified electron mobility at the interface of electrode beneficial for electrocatalytic analysis. rGO-Rubpy modified electrode enabled direct electrochemical redox reaction of quercetin, exhibiting a linear detection range of 0.05–50 µM, with a lowest detection limit of 0.002 µM. Demonstrated label-free sensor platform display selectivity toward quercetin even in the presence of interferents and sensitivity in the real sample, promising for complementary analytical application.

Endohedral metallofullerene single molecule magnets

Nanoscale magnetic materials have been attracting enormous interests during the past few decades due to the rapid development of high-density magnetic storage devices. A breakthrough in nanomagnetism is the discovery of single molecule magnets (SMMs), which exhibit slow relaxation and quantum tunneling of the magnetization resulted from a molecular-based blocking anisotropy, and thus have potential applications in high-density data storage, molecular spintronics and quantum computing. Since the report of Mn12-complex as the first SMM by Sessoli et al. in 1993, a large number of SMMs based on organometallic coordination compounds have been synthesized. Compared to the traditional bulk magnets, the magnetic properties of SMMs are determined by their instrinsic spin structures resulting in slow magnetic relaxation. SMM is characterized by a bi-stable magnetic ground state and a certain spin-reversal barrier ( U eff). Additionally, hysteresis loops can be observed below the blocking temperature ( T B). Therefore, SMMs with excellent magnetic properties always have high T B and U eff. U eff depends strongly on spin ground state ( S ) and magneto-crystalline anisotropy ( D ), and can be expressed with the formula U eff =| D|S 2. For transition metal-based SMMs, their low magneto-crystalline anisotropies ( D ) result in relative low U eff. In recent years, lanthanide based SMMs have been studied intensively and become the most promising high-performance SMMs, owning to their strong single ion anisotropy. Encapsulating metal atoms or metallic clusters into fullerene cages generate a special class of fullerenes, the so-called endohedral metallofullerenes (EMFs), for which the encapsulation of metal atoms endow EMFs more fascinating properties compared to empty fullerenes. For instance, EMFs are paramagnetic when the entrapped metal ions have unpaired electrons. Furthermore, EMFs were able to show excellent SMM properties when the encapsulated clusters induce appropriate ligand-fields. EMFs with lanthanide open up a new avenue in the field of SMMs in 2012 when single molecule magnetism was proved for the metal nitride clusterfullerene (NCF) DySc2N@ I h-C80. Fullerene cages are stable in air and thus they can protect the magnetic ions from ambient conditions, and the negatively charged nonmetallic atom(s) within the cluster and the negatively charged carbon atoms of fullerene cages provide magnetic anisotropy which is necessary for single molecule magnetism. Moreover, the molecular structures of EMFs can be modulated by varying the encapsulated metal ions, metal cluster and cage isomer; hence the research on EMF-SMMs has been developed rapidly since 2012. Up to now, metal nitride clusterfullerenes (NCFs), metal carbide clusterfullerenes (CCFs), metal oxide clusterfullerenes (OCFs), metal sulfide clusterfullerenes (SCFs), metal cyanide clusterfullerenes (CYCFs) and dimetallofullerenes (di-EMFs) have been confirmed as SMMs. In this paper, we present an exhaustive review on all kinds of EMF-SMMs reported to date including their 1D, 2D and 3D assemblies. We mainly discuss the influences of the types and the numbers of the encapsulated metal ions and non-metal atoms on the magnetic properties of EMF-SMMs. Finally, the prospects and challenges of EMF-SMMs are also discussed.

Combined Experimental and Theoretical Molecular Approach of the Catalytically Active Hydrotreating MoS2 Phases Promoted by 3d Transition Metals

High-throughput synthesis combined with a surface organometallic (coordination) chemistry approach is used to prepare in a systematic way a series of 40 metal-promoted (Me)–MoS2 active phases suppo...

Assigning the ESI mass spectra of organometallic and coordination compounds

Organometallic compounds are a class of substances containing at least one metal-to-carbon bond in which the carbon is part of an organic group. These constitute a very large group of substances that are often used as catalysts and as intermediates in the laboratory and in industry. Overall, organometallic compounds continue to play a significant role in the development of chemistry. In this tutorial special feature article, Scott McIndoe and Krista Vikse briefly summarize the techniques that are commonly used to assign any ESI-MS spectrum, and the various types of ions one is likely to observe from organometallic systems or coordination compounds. They then suggest a systematic procedure specifically designed for the ESI-MS analysis of organometallic and coordination systems and demonstrate its usefulness through two case studies. J. Scott McIndoe is Professor of Chemistry at the University of Victoria (Victoria BC, Canada). Krista L. Vikse is Assistant Professor of Chemistry at San Francisco State University (San Fransisco CA, USA). Their research interests are centered in organometallic catalysis and synthesis, and the development and use of novel MS (and orthogonal spectroscopic) techniques to enable rapid catalyst discovery, mechanism elucidation and reaction optimization via real-time analysis.

Fac-Re(CO)3-based organometallic supramolecular coordination complexes using thiophene motif decorated flexible ditopic benzimidazolyl donor

Thiophene/bithiophene units decorated flexible ditopic benzimidazolyl donors (Ln) were synthesized. Neutral, heteroleptic, dinuclear rhenium(I)-based organometallic supramolecular coordination complexes (SCCs) (1–4) were synthesized using Ln, Re2(CO)10 and tetrahydroxy-p-benzoquinone via one-step procedure. All the molecules were characterized by various methods. SCCs 1, 2 and 4 were further analyzed by X-ray analysis. All the ligands and the complexes are emissive at room temperature.

Supramolecular Chemistry of Cobalt-Corrins

Cobalt corrins are chiral relatives of the cobalt porphyrins, in which the ligand is much less unsaturated and is also ‘contracted’ by one carbon. This type of ligand strongly affects the redox and coordination chemistry of the bound cobalt center. Some lipophilic artificial cobalt corrins have been prepared in tremendous synthetic efforts in the Eschenmoser labs. The natural analogues offer an apparently more straight forward chemical entry to cobalt corrins. However, the natural cobalt corrins are all hydrophilic and highly substituted at their periphery, and they are distantly related to heme and chlorophyll. Although these cobalt corrins are very soluble in water, their natural roles are intimately connected with their essential and rich organometallic chemistry, which is all cobalt-centered.[1] In this lecture, means for specific supramolecular assemblies based on modified natural cobalt corrins are delineated, as well as consequences of the supramolecular restructuring on the organometallic and redox-chemistry. So far, in the excursions to be reported, the cobalt corrin core is not altered and its redox and spectral properties are largely conserved. A unique basis for specific supramolecular assemblies is then provided by the (organometallic) ligand itself, either, when attached to and bridging more than one metal center, or, when providing a structuring interface itself, for the build-up of supra-molecules. In a second general type of supramolecular assemblies the functional groups attached at the peripheral substituents of the natural corrinoids are used in a uniform way. By this means, the direct environment of the cobalt corrin moiety may be affected and structured in a global fashion, generating, e.g., a type of molecular micelles. A third type of supramolecular assembly makes selective use of single sites of the complex, but largely conserved sphere of the peripheral substituents, in order to generate specifically structured cobalt-corrins and their dimers. These latter ones may feature binuclear (organometallic) coordination chemistry, which would allow for synchronized redox processes in a highly structured, ‘second’ sphere around the metal centers. I thank the Austrian Science Foundation (FWF, project P-28892 and earlier projects) for generous financial support.

Copper-Phenylacetylide Nanobelt/Single-Walled Carbon Nanotube Composites: Mechanochromic Luminescence Phenomenon and Thermoelectric Performance.

We report flexible films of organic-inorganic thermoelectric (TE) composites based on organometallic coordination compound [copper-phenylacetylide (PhC2Cu)] nanobelts and single-walled carbon nanotubes (SWCNTs). Interestingly, an unusual mechanochromic luminescence phenomenon from bright green to dark red is clearly observed after grinding the PhC2Cu crystalline nanobelts. The PhC2Cu/SWCNT composites display high mechanical flexibility and excellent TE performance. The maximum power factor at room temperature can reach as high as 200.2 ± 10.9 μW m-1 K-2. The present study opens an avenue to fabricate novel organic-inorganic TE composite materials using organometallic coordination compounds such as PhC2Cu.

Coordination polymers and discrete complexes of Ag(I)-N-(pyridylmethylene)anilines: synthesis, crystal structures and photophysical properties

Reactions of AgO2C2F3 with (E)-N-(pyridylmethylene)aniline in which the pyridyl N is in the p- or m-position yielded two 1-D coordination polymers, [(AgO2C2F3)2(La)2]n (La = (E)-2,6-diisopropyl-N-(pyrid-3-ylmethylene)aniline) (1) and [(AgOC2F3)2(Ld)2]n (Ld = (E)-2,6-diisopropyl-N-(pyrid-4-ylmethylene)aniline) (5), and three discrete complexes, [(AgO2C2F3)2(La)4] (2), [AgO2C2F3(Lb)2] (Lb = (E)-N-(pyrid-4-ylmethylene)aniline) (3) and [(AgOC2F3)2(Lc)4] (Lc = (E)-2,6-dimethyl-N-(pyrid-4-ylmethylene)aniline) (4). The structures were determined by MS, FT-IR and NMR spectroscopies, elemental analysis and single crystal XRD. 1 is an organometallic coordination polymer with silver in η1-arene coordination, but is a discrete dimeric complex 2 when crystallized from warm diethylether. The geometries around silver(I) in 1 and 4 are tetrahedral, ‘inverted seesaw’ in 2 and T-shaped in 3 and in all the anion seems to play a role. Ag(I) centers in 5 have distorted trigonal bipyramid and inverted seesaw geometries. The trifluoroacetate anions in these complexes display variable monodentate and short bridging coordination patterns. All complexes absorb and strongly emit UV-Vis radiation at room temperature.

Ruthenium(II) and Ruthenium(III) Complexes of p-Benziporphyrin: Merging Equatorial and Axial Organometallic Coordination.

A diamagnetic ruthenium(II) complex of 5,10,15,20-tetraphenyl-p-benziporphyrin [RuII(p-BzP)(CO)Cl] was obtained via the insertion of ruthenium into p-benziporphyrin using triruthenium(0) dodecacarbonyl [Ru3(CO)12] as the metal source. The procedure applying dichloro(cycloocta-1,5-diene)ruthenium(II) (polymer, [Ru(COD)Cl2]n) afforded the paramagnetic six-coordinate ruthenium(III) p-benziporphyrin [RuIII(p-BzP)Cl2]. As shown by X-ray crystallography, the p-phenylene ring in both complexes is sharply tilted out of the N3 plane, as reflected by the respective N3 (pyrrole)-C6 (p-phenylene) dihedral angle [RuII(p-BzP)(CO)Cl, 52.5°; RuIII(p-BzP)Cl2, 53.7°]. p-Phenylene is bound to the ruthenium cation in an η2 fashion, revealing the shortest ever Ru-C distance in the series of p-benziporphyrin complexes [RuII(p-BzP)(CO)Cl, 2.275(2) Å; RuIII(p-BzP)Cl2, 2.324(5) Å]. The reaction of RuII(p-BzP)(CO)Cl with ArMgCl or AlkMgCl results in the formation of diamagnetic six-coordinate ruthenium(II) p-benziporphyrin complexes containing the apically coordinated σ-alkyl or σ-aryl ligands, where the metal ion simultaneously coordinates to three carbon centers respectively accommodating η2 (phenylene) and σ (aryl and alkyl) modes. Reactions of σ-aryl (alkyl) carbanions with paramagnetic RuIII(p-BzP)Cl2 have been followed by 1H NMR spectroscopy. The procedure afforded the six-coordinate paramagnetic ruthenium(III) p-benziporphyrin [RuIII(p-BzP)(Ph)Cl], which binds one σ-aryl ligand, as reflected by the characteristic 1H NMR spectra spread within the +120 to -120 ppm range. Both paramagnetic complexes RuIII(p-BzP)(Ph)Cl and RuIII(p-BzP)(p-Tol)Cl are formed as a mixture of two stereoisomers differentiated by two nonequivalent locations of σ-aryl with respect to the puckered macrocyclic ring. The paramagnetic shifts of σ-aryls are indicative of π-spin delocalization patterns. Analysis of the contact shifts and parallel density functional theory calculations of the spin density distribution in RuIII(p-BzP)Cl2, RuIII(p-BzP)(Ar)Cl, and RuIII(p-BzP)(Alk)Cl reflect the features of the dxy2(dxzdyz)3 electronic ground state.

Sodium chloride nanorods from nanorods of one-dimensional pencil-shaped sodium coordination polymer

By considering the structure of one-dimensional pencil-shaped organometallic coordination polymer that was previously reported, we designed and synthesized [Na(μ2-Hdcpa)(μ3-dcpa)]n (1), [Hdcpa = 2,4-dichlorophenoxyacetic acid], which has one-dimensional pencil-shaped structure too. The Na atoms are surrounded with the aromatic phenyl rings of Hdcpa similar to graphite of a pencil. Metalophilic interactions also exists in 1 between Na(I) ions similar to argentophilic interaction in our previous compound which results in formation of chain structure similar to graphite structure of a pencil. Compound 1 nanorods were formed under ultrasonic irradiation and applied as template to fabricate sodium chloride nanorods. The interesting feature of our work is the formation of sodium chloride nanorods from compound 1 nanorods which have one-dimensional structure in the solid state.

Metallacyclopentadienes: synthesis, structure and reactivity.

Metallacyclopentadienes, which possess two M-C(sp2) bonds and feature the structure of M(C[upper bond 1 start]R1[double bond, length as m-dash]CR2-CR3[double bond, length as m-dash]C[upper bond 1 end]R4), are an important class of five-membered metallacycles. They are considered as both reactive intermediates in the stoichiometric and catalytic transformations of organic molecules and useful precursors to main group element compounds, and have received considerable attention in organometallic chemistry, coordination chemistry and synthetic organic chemistry over the past six decades because of their unique metallacyclic structure. This review comprehensively presents the synthesis, structure and reactivity of the s-, p-, d- and f-block metallacyclopentadienes distributed in the whole periodic table. In addition, their application in synthetic organic chemistry and polymer chemistry is summarized. This review aims to be beneficial for the design and synthesis of novel metallacyclopentadienes, and for promoting the rapid development of metallacyclic chemistry.

Quasi-one-dimensional spin-orbit-coupled correlated insulator in a multinuclear coordinated organometallic crystal

We show how quasi-one-dimensional correlated insulating states arise at two-thirds filling in organometallic multinuclear coordination complexes described by layered decorated honeycomb lattices. The interplay of spin-orbit coupling and electronic correlations leads to pseudospin-1 moments arranged in weakly coupled chains with highly anisotropic exchange and a large trigonal splitting. This leads to a quantum phase transition from a Haldane phase to a topologically trivial phase as the relative strength of the spin-orbit coupling increases.

Synthesis, Structure and Reactivity of Cyclometalated Nickel(II) Complexes: A Review and Perspective

The importance of cyclometalated Ni(II) complex species assumed in catalytic processes related to C–X or C–H activation and functionalisation e.g. in C–C cross coupling reactions stands in stark contrast to the small number of investigations on the synthesis, reactivity, electrochemical and spectroscopic properties of cyclometalated complexes to model catalytically relevant species. This review reveals that the methods to synthesise cyclometalated Ni(II) complexes are rather weakly developed compared with corresponding Pd or Pt derivatives. Furthermore, cyclometalated ligands with their strongly σ-donating carbanionic functions, their chelate effect and often good π-accepting properties are also interesting from the general viewpoint of organometallic coordination chemistry and applications beyond catalysis. The recently reported cyclometalated complexes [Ni(Phbpy)(R)] with the carbanionic Phbpy− = 6-(phenyl-2-ide)-2,2′-bipyridine ligand (R = Br, CH3, CF3) were described in detail to demonstrate some of the specific properties of such cyclometalated complexes. Further ligand design might allow to synthesise cyclometalated Ni(II) complexes with very interesting properties such as efficient triplet luminescence. What has been achieved in this field with Pt(II) and Pd(II) might be transferred to Ni(II) in the future and some ideas are presented.

Design and compressibility of Langmuir monolayers from organometallic nanocyclic complexes

We propose to control design of organometallic conducting Langmuir monolayer by utilizing geometrodynamic approach. By means of this approach the compressibility of the monolayer, which consists of molecules of thiophene-pyrrole series oligomer with covalently bound hydrophobic alkyl chain, has been analyzed for different subphase with iron salts. It has been discovered that the monolayers are polymerized and turn into monolayers of nanocyclic organometallic coordination compounds at a two-dimensional phase transition of the first order.

Crystal structure of 4,4-di-bromo-1-(3,4-di-meth-oxy-phen-yl)-2-aza-buta-1,3-diene-1-carbo-nitrile.

The title compound, C12H10Br2N2O2, represents an example of a planar π-con-jugated 2-aza-butadiene mol-ecule, which is both an inter-esting starting material for further organic transformations and a potential ligand in organometallic coordination chemistry. Its metric mol-ecular parameters are typical for the family of 2-aza-buta-1,3-dienes not substituted at the (CH) 3-position. In the crystal, the almost planar (r.m.s. deviation = 0.0658 Å) aza-diene mol-ecules form one-dimensional double-wide ribbons through inter-molecular halogen bonds (C-Br⋯O and C-Br⋯Br-C), which then stack in a slipped manner through weak C-H⋯Br and π-π inter-actions to generate a three-dimensional network.

Core-Shell Coating Silicon Anode Interfaces with Coordination Complex for Stable Lithium-Ion Batteries.

In situ core-shell coating was used to improve the electrochemical performance of Si-based anodes with polypyrrole-Fe coordination complex. The vast functional groups in the organometallic coordination complex easily formed hydrogen bonds when in situ modifying commercial Si nanoparticles. The incorporation of polypyrrole-Fe resulted in the conformal conductive coating surrounding each Si nanoparticle, not only providing good electrical connection to the particles but also promoting the formation of a stable solid-electrolyte-interface layer on the Si electrode surface, enhancing the cycling properties. As an anode material for Li-ion batteries, modified silicon powders exhibited high reversible capacity (3567 mAh/g at 0.3 A/g), good rate property (549.12 mAh/g at 12 A/g), and excellent cycling performance (reversible capacity of 1500 mAh/g after 800 cycles at 1.2 A/g). The constructed novel concept of core-shell coating Si particles presented a promising route for facile and large-scale production of Si-based anodes for extremely durable Li-ion batteries, which provided a wide range of applications in the field of energy storage of the renewable energy derived from the solar energy, hydropower, tidal energy, and geothermal heat.