Rhenium Atoms Research Articles

The first examples of dirhenium(III,II) paramagnetic complexes with bridging diphenylphosphinomethane and 2-mercaptopyridine ligands: A collective experimental and theoretical studies

2-mercaptopyridine (H-pySH), 5‑chloro-2-mercaptopyridine (Cl-pySH) and 5-trifluoromethyl-2-mercaptopyridine (F3C-pySH) ligands react with the multiply‒bonded paramagnetic dirhenium(III,II) complex [Re2(μ-O2CCH3)Cl4(μ-dppm)2] (1) [dppm is Ph2PCH2PPh2] in refluxing ethanol to afford the paramagnetic substitution products of the type [Re2(μ-dppm)2(μ-R-pyS)2Cl2]Cl (2(R)) [R = H, Cl, CF3]. These are the first examples of paramagnetic dirhenium complexes that contain the bridging mercaptopyridine ligand. These complexes have very similar spectral (UV–vis, IR, EPR) and electrochemical properties which are also reported. The identity of 2(H) and 2(CF3) has been established by single-crystal X-ray structure determination (ReRe distance ∼2.29 Å). The electronic structures and optical properties of the complexes are scrutinized by density functional theory (DFT) and time-dependent DFT studies. DFT calculation shows that the highest occupied molecular orbital (HOMO) corresponds to a δ* interaction between the d-orbitals of rhenium atoms and π* interaction between the sulphur atoms and the rhenium centers whereas the lowest unoccupied molecular orbital (LUMO) is the Re2π* based orbital.

Natural rhenium sulfide clusters formed under conditions of laser desorption-ionization.

Cluster forms of rhenium sulfides have important practical applications as catalysts in oil refining and thus present high interest. However, only a limited number of rhenium sulfide clusters have been described previously. It is known that cluster formation actively occurs under conditions of laser desorption-ionization; nevertheless, detailed studies of rhenium sulfides under such conditions were apparently not conducted previously. A sample of natural rhenium sulfide, collected from the fumarolic field of Kudriavy volcano (Iturup island, Russia) in 2002, was investigated using the laser desorption-ionization mass spectrometry method. The formed rhenium sulfide clusters were registered by a time-of-flight detector and identified programmatically using the software developed in IPCE RAS. The identification involved a comparison of the distribution of isotopic peak intensities, observed in the resulting mass spectra, with the theoretical probabilities of occurrence of various isotopologues for hypothetical rhenium sulfide species. Over 60 rhenium sulfide clusters of RexSy + and RexSyOz - types containing up to 10 rhenium atoms were formed when a sample of natural rhenium sulfide was exposed to laser desorption-ionization conditions. Several isolated heterometallic ReXMoSY + and ReXMoSYOZ - clusters containing up to eight rhenium atoms were additionally observed in the resulting mass spectra. The species with compositions, for which the electrically neutral analogs are known, apparently were the most stable rhenium sulfide clusters among the detected ones. The obtained data allowed summarizing the patterns of formation of rhenium sulfide clusters under conditions of laser desorption-ionization. The ability of rhenium and sulfur to form cluster species containing from 7 to 10 atoms of rhenium was likely discovered for the first time. The majority of the rhenium sulfide clusters described in this study, notably RexSy + ions containing over seven atoms of rhenium, were apparently not observed previously.

Facile C[sbnd]H aryl and O[sbnd]H bonds activation at dirhenium site of [Re2(CO)8(THF)2] complex

The activation of small molecules is a topic of great interest and previously we reported on the easy activation of different types of EH bonds at the dinuclear complex [Re2(CO)8(THF)2] (1) where labile THF molecules coordinate to adjacent rhenium(0) atoms. Here we extend the reactivity of 1 reporting on the oxidative addition of benzene and toluene at room temperature to give [Re2(μ-H)(μ-κC-Ar)(CO)8], Ar = −C6H5 (2) and −C6H4Me (3). Compound 3 is a new example of μ-κC-Ar dinuclear rhenium complex and has been obtained as para and meta isomers (3a,b). It is known from the literature that 2 can activate arenes and heteroarenes via reductive elimination of benzene and oxidative addition of CH bonds to the dinuclear fragment. Here we have studied the reaction of 2 with C6D6 and H2CC(H)Ph and determined the kinetic constants by 1H NMR (1.4 × 10−5 s−1 at 308 K and 1.1 × 10−5 s−1 at 298 K, respectively). The results indicate that the rate-determining step of the reaction is the reductive elimination of benzene, while the oxidative addition is fast. Water and methanol react with 1 in toluene at room temperature to give the hydroxo and methoxo hydrido complexes [Re2(μ-H)(μ-OR)(CO)8], RH (5) and CH3 (6). On reacting 1 with water in deuterated toluene, and monitoring by 1H/2H NMR, a preferential deuteration of the hydride site to give [Re2(μ-D)(μ-OH)(CO)8] is evidenced. This finding excludes the oxidative addition of water on the dinuclear “Re2(CO)8” fragment while supporting a heterolytic addition of water via protonation at the µ-κC-tolyl group, elimination of toluene and addition of OH−. Single crystal X-ray diffraction analyses have been performed for complexes 3a, 5 and 6 and their solid state structures have been determined. In particular, the crystal structure of 5 results in a new polymorphic form (5b) and it is discussed in comparison with the already known one (5a).

First-principles study of Re in BCC-Mo: Diffusion behavior and interaction with point defects

Due to their some beneficial properties, molybdenum-based alloys, such as Mo-Re alloys, are recognized as potential structural materials for nuclear power reactors. Irradiation induced precipitation of rhenium (Re) atoms causes hardening and embrittlement of Mo-Re alloys, restricting their application. The interaction of rhenium (Re) atoms with point defects (PDs), as well as the diffusion behavior of Re atoms in BCC-Mo (Body Center Cubic-molybdenum), were investigated using first-principles methods. The results revealed that Re atoms exhibited high binding energies with both vacancy (Vac) and interstitial dumbbells. Furthermore, the binding energies increased with the number of Re atoms. The binding energies of Re with self-interstitial dumbbell (SIA, ie., Mo-Mo) and mixed interstitial dumbbell (Mo-Re) were quite close to. Due to the high exchange barrier between Vac and Re, the diffusion of rhenium through the vacancy-drag mechanism was difficult. Due to the low migration and rotation barrier of Mo-Re mixed interstitial dumbbell, the diffusion of Re atoms in Mo was dominated by the interstitial-mediated mechanism. From the perspective of diffusion dynamics, only interstitial dumbbells can promote the aggregation of Re atoms. By comparing the binding energy of interstitial dumbbell with interstitial dumbbell and interstitial dumbbell with Re atoms, pairs of Mo-Re interstitial dumbbell was suggested to be the nucleation sites to attract more interstitial dumbbells, thereby promoting the precipitation of Re clusters. It was because they had high binding energy and were difficult to decompose once combined.

Comparative study of the electronic and optical properties of Rhenium based Chalcogenides

Transition metal dichalcogenides are materials of growing interest due to their unique electronic properties and rich phase diagram, offering promising opportunities for various applications. In this study, we investigate the optoelectronic characteristics of two-dimensional rhenium (Re)-based chalcogenides. These materials are composed of rhenium atoms sandwiched between chalcogen layers. In this paper, we have selected three rhenium-based chalcogenide (ReS2, ReSe2 and ReTe2) compounds in their 1T structure and calculated their electronic properties. Our study aims to find the intricacies of theoretical band structures and optical properties, aiming to assess their viability as semiconducting materials for the optoelectronics industry employing density funtional theory. Furthermore, we explore the impact of varying chalcogen compositions on the optoelectronic behavior, uncovering the tunability of these materials for specific applications. The study provides insights into the role of Re-based chalcogenides as promising candidates for emerging technologies, including photodetectors, solar cells, and other optoelectronic devices. The observed band gaps highlight the potential of these materials within the infrared region of the electromagnetic spectrum. After observing optical properties derived from our calculations, we discuss the corresponding potentials of the chosen materials in optoelectronic applications.

First-principales study of the structural, magnetic and optoelectronic properties of double perovskite Ba2FeReO6

In this study, we investigate the electronic, magnetic, and optical properties of the Ba2FeReO6 double perovskite using density functional theory within the framework of the full-potential linearized augmented plane Wave method. We employ various approximations including GGA-PBE, GGA + U (Hubbard Coulomb correction), and GGA plus Spin-Orbit coupling (GGA + SOC). The densities of states and spin-polarized band structure reveal a half-metallic behavior with a magnetic moment of 3 μ B for all approximations, with iron and rhenium atoms contributing the most to the overall magnetic moment. Regarding optical properties, it can be stated that the Ba2FeReO6 material exhibits strong absorption and holds potential for application across a wide energy range spanning from visible to ultraviolet light spectra in future spintronics and optoelectronic technologies.

1,2,3-Triazol-5-ylidene- vs. 1,2,3-triazole-based tricarbonylrhenium(I) complexes: influence of a mesoionic carbene ligand on the electronic and biological properties.

The tricarbonylrhenium complexes that incorporate a mesoionic carbene ligand represent an emerging and promising class of molecules, the solid-state optical properties of which have rarely been investigated. The aim of this comprehensive study is to compare three of these complexes with their 1,2,3-triazole-based analogues. The Hirshfeld surface analysis of the crystallographic data revealed that the triazolylidene derivatives are more prone to π-π interactions than their 1,2,3-triazole-based counterparts. The FT-IR and electrochemical data indicated a stronger electron donor effect from the organic ligand to the rhenium atom for triazolylidene derivatives, which was confirmed by DFT calculations. All compounds were phosphorescent in solution, where the 1,2,3-triazole-based complexes showed unusually strong dependence on dissolved oxygen. All compounds also emitted in the solid state, some of them exhibited marked solid-state luminescence enhancement (SLE) effect. The 1,2,3-triazole based complex Re-Phe even displayed astounding photoluminescence efficiency with quantum yield up to 0.69, and proved to be an excellent candidate for applications linked to aggregation-induced emission (AIE). Interestingly, one triazolylidene-based complex (Re-T-BOP) showed attractive antibacterial activity. This study highlights the potential of these new molecules for applications in the fields of photoluminescent and therapeutic materials, and provides the first bases for the design of efficient molecules in these research areas.

Formation of silyl metal hydride, HMnSiH3 and silylidyne, H3ReSiH in the activation of silane by manganese and rhenium atoms

The reactions of laser ablated manganese and rhenium metal atoms with silane molecules in low temperature argon matrix were studied. The experimental and theoretical results indicate that the reaction happened after the metal atoms were excited to Mn(6P) or Re(6P) excited states upon photolysis. Combining the isotopic shifts of the infrared absorptions and quantum chemical calculations, the silyl metal hydride HMnSiH3 and the silylidyne H3ReSiH were identified in the argon matrix. The vibronic coupling between the ground state X2A' and the first excited state A2A'' leads to a bond angle H-Si-Re of 130.4° in the doublet ground state H3ReSiH.

Direct observation of voids decorated with transmuted rhenium atoms in neutron-irradiated tungsten by correlative use of TEM and APT

The microstructure of tungsten (W) irradiated by neutrons up to 1.54 displacements per atom at 750 ℃ in the fast-neutron experimental reactor Joyo, where the thermal neutron ratio is low, was characterized by observing same needle specimen by both transmission electron microscopy (TEM) and atom probe tomography (APT). TEM showed nanoscale voids with a high number density in the matrix, while APT showed nanoscale rhenium (Re)-enriched clusters with a similar number density in the matrix. By comparing the TEM image and APT map in the same area of the same needle specimen, a one-to-one correspondence was clearly obtained between the voids observed by TEM and the Re-enriched clusters observed by APT. Furthermore, the size distributions for the voids and Re-enriched clusters were almost the same. Thus, it was found that all voids were decorated with transmuted Re atoms in the (initially pure) W neutron-irradiated in Joyo where the thermal neutron ratio is low.

Structural features of monomeric octahedral <i>d</i><sup>2</sup>-rhenium dioxo complexes with monoand bidentate ligands [reo<sub>2</sub>(l<sub>bi</sub>)(l<sub>mono</sub>)<sub>2</sub>], [reo<sub>2</sub>(l<sub>bi</sub>)<sub>2</sub>] (a review)

Structural features of mononuclear octahedral dioxo complexes d 2-Re5+, [ReO2(Lbi)(Lmono)2], [ReO2(Lbi)2] with mono- and bidentate ligands were considered. The multiply bound Ooxo ligands are located predominantly in trans -positions to each other, with two exceptions, with the cis -orientaion of the ReO2 fragment. Rhenium atoms in most complexes have the trans -octahedral ReOoxo2X4 (X = N, P, As, O) coordination, in two cases they have the cis -octahedral ReOoxo2N4 structure. Re=Ooxo bonds in d 2-Re(V) monomeric octahedral dioxo compounds ( d average 1.772 Å) are much longer than in d 2-Re(V) monooxo complexes ( d average 1.676-1.699 Å).

Excellent spin filtering and significant magnetoresistance of rhenium phthalocyanine molecular junctions on Au(100)

Spin transport properties of single rhenium phthalocyanine (RePc) and double-rhenium phthalocyanine (Re2Pc2) molecular devices with gold electrodes have been investigated by combining Density Functional theory and nonequilibrium Green’s functions. It was found that the RePc molecular devices exhibited good spin filtration efficiency in the small bias range even in the absence of magnetic electrodes. The Re2Pc2 molecular device exhibited a large magnetoresistance and excellent spin-filtering properties at a finite bias, which can only be achieved by altering the magnetization orientation of the rhenium atom at the center of the phthalocyanine molecule. These conclusions of the rhenium phthalocyanine molecule may have potential application in magnetoresistive devices and spin filters.

Coordination versus Insertion: On the Interaction of 5 d-Transition Metal Carbonyl Clusters with Silver(I).

The title silver(I) complex salts [Ag{Re2 (CO)10 }{Re(CO)5 }2 ]+ [Al(ORF )4 ]- (AgRe4 ; ORF =-OC(CF3 )3 ) and [Ag{Ir4 (CO)12 }2 ]+ [Al(ORF )4 ]- (AgIr8 ) form upon reaction of Ag+ [Al(ORF )4 ]- and the transition metal carbonyls (TMCs) Re2 (CO)10 and Ir4 (CO)12 respectively. The solid-state structure of the AgRe4 cluster shows an unexpected asymmetric coordination motif, wherein the silver(I) cation has inserted into the Re-Re bond of one Re2 (CO)10 moiety, while the other dirhenium carbonyl coordinates only over one metal atom towards the silver(I) cation. The AgIr8 cluster is formed by the edge-on coordination of two Ir4 tetrahedra and the silver cation in a D2 symmetric fashion with a torsion angle of 46.5°. QTAIM analysis shows bond paths between the silver atom and the nearby metal atoms in all cases, whereas only the non-inserted Re2 (CO)10 moiety shows additional bond paths between the carbonyl ligands and the silver cation. In addition, the insertion of the Ag+ cation into the Re-Re bond in Re2 (CO)10 removes the bond path between the two rhenium atoms. The EDA-NOCV analysis suggests an increase of the interaction energy between the silver(I) cation and the respective metal carbonyls from the metal centered transition metal carbonyl (TMC) donors W(CO)6 <Re2 (CO)10 <Os3 (CO)12 <Ir4 (CO)12 . In all cases, the dominating orbital interaction is σ-donation [TMC]→Ag+ ←[TMC].

Dimer Rhenium Tetrafluoride with a Triple Bond Re-Re: Structure, Bond Strength.

Based on the data of the gas electron diffraction/mass spectrometry (GED/MS) experiment, the composition of the vapor over rhenium tetrafluoride at T = 471 K was established, and it was found that species of the Re2F8 is present in the gas phase. The geometric structure of the Re2F8 molecule corresponding to D4h symmetry was found, and the following geometric parameters of the rh1 configuration were determined: rh1(Re-Re) = 2.264(5) Å, rh1(Re-F) = 1.846(4) Å, α(Re-Re-F) = 99.7(0.2)°, φ(F-Re-Re-F) = 2.4 (3.6)°. Calculations by the self-consistent field in full active space approximation showed that for Re2F8, the wave function of the 1A1g ground electronic state can be described by the single closed-shell determinant. For that reason, the DFT method was used for a structural study of Re2X8 molecules. The description of the nature of the Re-Re bond was performed in the framework of Atom in Molecules and Natural Bond Orbital analysis. The difference in the experimental values of r(Re-Re) in the free Re2F8 molecule and the [Re2F8]2- dianion in the crystal corresponds to the concept of a triple σ2π4 (ReIV-ReIV) bond and a quadruple σ2π4δ2 (ReIII-ReIII) bond, respectively, which are formed between rhenium atoms due to the interaction of d-atomic orbitals. The enthalpy of dissociation of the Re2F8 molecular form in two monomers ReF4 (ΔdissH°(298) = 109.9 kcal/mol) and the bond energies E(Re-Re) and E(Re-X) in the series Re2F8→Re2Cl8→Re2Br8 molecules were estimated. It is shown that the Re-Re bond energy weakly depends on the nature of the halogen, while the symmetry of the Re2Br8 (D4d) geometric configuration differs from the symmetry of the Re2F8 and Re2Cl8 (D4h) molecules.

Re12C80: A pentagonal hexecontahedron molecule

Based on density-functional theory calculations, a polyhedron molecule, Re12C80 cage, was proposed and showed topological analogy to Catalan pentagonal hexecontahedron. The geometric topology of Re12C80 molecule retains integrity when the effective temperature is up to 782 K. Its electronic structure shows that for the carbon atom there is the feature of sp2-like hybrid orbital, and for the rhenium atom there presents d orbital characteristics. The large hollow space for Re12C80 cage can be useful to encapsulate other atoms or small molecules. The proposal of Re12C80 molecular structure can help to enrich and expand the types of highly symmetric polyhedral molecules.

Engineering Magnetic Anisotropy of Rhenium Atom in Nitrogenized Divacancy of Graphene.

The effects of charging on the magnetic anisotropy energy (MAE) of rhenium atom in nitrogenized-divacancy graphene (Re@NDV) are investigated using density functional theory (DFT) calculations. High-stability and large MAE of 71.2 meV are found in Re@NDV. The more exciting finding is that the magnitude of MAE of a system can be tuned by charge injection. Moreover, the easy magnetization direction of a system may also be controlled by charge injection. The controllable MAE of a system is attributed to the critical variation in dz2 and dyz of Re under charge injection. Our results show that Re@NDV is very promising in high-performance magnetic storage and spintronics devices.

Matere Bonds in Technetium Compounds: CSD Survey and Theoretical Considerations

Noncovalent interactions involving metals as electron acceptors are continuously under investigation. The term “matere bond” has been proposed to identify noncovalent donor–acceptor interactions where elements of group 7 of the periodic table play the role of the electrophilic site. Most of the works on matere bonds involve rhenium atoms usually in +7 oxidation state. This work emphasizes for the first time their importance in technetium derivatives in several oxidation states (+7, +6, +5, and +3). The Cambridge Structural Database (CSD) in combination with density functional theory (DFT) calculations are used to demonstrate the structure directing role of matere bonds in X-ray structures, even involving anion⋯anion interactions. Further characterization of the matere bonds is provided using Molecular Electrostatic Potential (MEP) surface calculations, the “Quantum Theory of Atoms in Molecules” (QTAIM), and Natural Bond Orbital (NBO) analyses. It should be emphasized that some types of matere bonds reported herein have not been previously described in literature.

Тонкие наноструктурированные пленки n-WSe2 и их применение в полупроводниковых фотокатодах p-Si для получения водорода расщеплением воды

The possibilities of modification of the structure and type of conductivity of WSe2 films formed on p-type silicon by thermal treatment of a thin-film precursor, which was preliminarily created by pulsed laser deposition, are studied. Pulsed laser ablation of WSe2 and rhenium targets made it possible to obtain amorphous films WSex (x &gt; 2) containing rhenium atoms and inclusions of β-W nanoparticles. Heat treatment at 450 °C caused the crystallization of the amorphous matrix and the formation of a layered 2H-WSe2 shell surrounded the metal nanoparticles. Doping with rhenium led to the production of n-type WSe2 semiconductor films, which, in terms of their properties (band gap ~ 1.2 eV, high catalytic activity, low resistance to current transport), represent a promising material for creating p-Si photocathodes for efficient light-activated hydrogen evolution in acid solution. Theoretical calculations are carried out, which make it possible to identify local areas on the surface of the formed WSe2 films with enhanced catalytic activity in hydrogen evolution reaction.

Replenishment in the Family of Rhenium Chalcobromides; Synthesis and Structure of Molecular {Re4S4}Br8(TeBr2)4, Dimeric [{Re4S4}Br8(TeBr2)3]2, and Polymeric {Re4S4}Br8 Compounds Based on the {Re4S4}8+ Tetrahedral Cluster Core.

We have obtained three new rhenium(IV) chalcobromides belonging to the homologous series {Re4S4}Br8(TeBr2)n (n = 0, 3, 4): a molecular complex {Re4S4}Br8(TeBr2)4 (1), a dimeric complex [{Re4S4}(TeBr2)3Br7(μ-Br)]2 (2), and a two-dimensional (2D) polymeric compound {Re4S4}Br8 (3). Compound 1 is isotypic to the already known {Re4Te4}(TeBr2)4Br8, while 2 and 3 exhibit a new type of binding of tetrahedral clusters via μ-Br bridges. Compounds were characterized by X-ray single-crystal diffraction, X-ray powder diffraction, and thermal and elemental analyses. In compound 2, two tetrahedral cluster cores {Re4S4}8+ are linked together forming a dimer through two Re-μ-Br-Re bridges. Calculations of the electron localization function (ELF) showed that there is no covalent interaction between rhenium atoms of neighboring clusters. In compound 3, each rhenium atom of the {Re4S4}8+ core is coordinated by three Br ligands: one terminal Br and two bridging μ-Br ligands. As a result, eight bridging bromine atoms link {Re4S4}8+ cluster cores into goffered layers. {Re4S4}Br8 is the new stable rhenium(IV) thiobromide, the first discovered in the Re-S-Br system, along with the already known octahedral rhenium(III) thiobromides Re6S4+xBr10-2x (x = 0-4).

Novel Class of Rhenium Borides Based on Hexagonal Boron Networks Interconnected by Short B2 Dumbbells.

Transition metal borides are known due to their attractive mechanical, electronic, refractive, and other properties. A new class of rhenium borides was identified by synchrotron single-crystal X-ray diffraction experiments in laser-heated diamond anvil cells between 26 and 75 GPa. Recoverable to ambient conditions, compounds rhenium triboride (ReB3) and rhenium tetraboride (ReB4) consist of close-packed single layers of rhenium atoms alternating with boron networks built from puckered hexagonal layers, which link short bonded (∼1.7 Å) axially oriented B2 dumbbells. The short and incompressible Re–B and B–B bonds oriented along the hexagonal c-axis contribute to low axial compressibility comparable with the linear compressibility of diamond. Sub-millimeter samples of ReB3 and ReB4 were synthesized in a large-volume press at pressures as low as 33 GPa and used for material characterization. Crystals of both compounds are metallic and hard (Vickers hardness, HV = 34(3) GPa). Geometrical, crystal-chemical, and theoretical analysis considerations suggest that potential ReBx compounds with x > 4 can be based on the same principle of structural organization as in ReB3 and ReB4 and possess similar mechanical and electronic properties.

C – C coupling of alkynes to the CH2 group in a 1-phosphonioethenyl ligand in a zwitterionic dirhenium carbonyl complex

Reactions of the zwitterionic dirhenium complex Re2(CO)8[μ-η2-1-C(CH2)(PMePh2)], 3 with the terminal alkynes, HCC(OEt) and HCCPh, have yielded two new isomeric ethoxy-substituted dirhenium complexes, Re2(CO)7[µ-η3-C(H)C(OCH2CH3)CH2C(PMePh2)], 5 and Re2(CO)7[µ-η3-C(OCH2CH3)C(H)CH2C(PMePh2)], 6 and one phenyl-substituted dirhenium complex Re2(CO)7[µ-η3-C(H)CPhCH2C(PMePh2)], 7, respectively, with each containing a bridging, substituted 1-phosphonio-3,4-butenyl ligand formed by loss of CO and the addition and coupling of one alkyne to the CH2 group of the 1-phosphonioethenyl ligand in 3. The bridging 1-phosphonio-3,4-butenyl ligand in compound 6 exhibits a dynamical “flip-flop” exchange for the phosphonio-3,4-butenyl ligand between the two rhenium atoms that leads to an averaging of the inequivalent protons on its methylene group that is rapid on the NMR timescale. When heated to 70oC, compound 5 was converted to two new compounds: Re2(CO)6(µ-H)[µ-η4-C(H)C(OCH2CH3)CHC(PMePh2)], 8, by loss of a CO ligand and a CH activation at the CH2 group in its C(H)C(OCH2CH3)CH2C(+PMePh2) ligand and an isomer Re2(CO)6(PMePh2)[µ-η4-C(H)C(OCH2CH3)CHCH], 9. Compound 9 was also obtained from 8 by heating to 80 °C for 5 days by shifting the PMePh2 group from its phosphonium carbon atom in 8 to one of the rhenium atoms to become a PMePh2 ligand in 9 and then shifting the hydrido ligand back to the same carbon atom to form a bridging η4-2-ethoxybutadiendiyl, [C(H)C(OCH2CH3)CHCH], ligand. All new products were characterized structurally by single-crystal X-ray diffraction analyses.