Metal Fragments Research Articles

Structure-property relationships of photofunctional diiridium(II) complexes with tetracationic charge and an unsupported Ir–Ir bond

In contrast to the extensively studied dirhodium(II) complexes and iridium(III) complexes, neutral or dicationic dinuclear iridium(II) complexes with an unsupported ligand are underdeveloped. Here, a series of tetracationic dinuclear iridium(II) complexes, featuring the unsupported Ir(II)–Ir(II) single bond with long bond distances (2.8942(4)–2.9731(4) Å), are synthesized and structurally characterized. Interestingly, compared to the previous unsupported neutral or dicationic diiridium(II) complexes, our DFT and high-level DLPNO-CCSD(T) results found the largest binding energy in these tetracationic complexes even with the long Ir(II)–Ir(II) bond. Our study further reveals that London dispersion interactions enhance the stability cooperatively and significantly to overcome the strong electrostatic repulsion between two half dicationic metal fragments. This class of complexes also exhibit photoluminescence in solution and solid states, which, to our knowledge, represents the first example of this unsupported dinuclear iridium(II) system. In addition, their photoreactivity involving the generation of iridium(II) radical monomer from homolytic cleavage was also explored. The experimental results of photophysical and photochemical behaviours were also correlated with computational studies.

Metal-Ligand Role Reversal: Hydride-Transfer Catalysis by a Functional Phosphorus Ligand with a Spectator Metal.

Hydride transfer catalysis is shown to be enabled by the nonspectator reactivity of a transition metal-bound low-symmetry tricoordinate phosphorus ligand. Complex 1·[Ru]+, comprising a nontrigonal phosphorus chelate (1, P(N(o-N(2-pyridyl)C6H4)2) and an inert metal fragment ([Ru] = (Me5C5)Ru), reacts with NaBH4 to give a metallohydridophosphorane (1H·[Ru]) by P-H bond formation. Complex 1H·[Ru] is revealed to be a potent hydride donor (ΔG°H-,exp < 41 kcal/mol, ΔG°H-,calc = 38 ± 2 kcal/mol in MeCN). Taken together, the reactivity of the 1·[Ru]+/1H·[Ru] pair comprises a catalytic couple, enabling catalytic hydrodechlorination in which phosphorus is the sole reactive site of hydride transfer.

Sharp-Pointed Foreign Body Ingestion in Pediatric Age.

To assess the clinical complications reported after the ingestion of sharp/pointed foreign bodies (FBs) in pediatric age, their incidence among all FB ingestions, and the features and clinical presentation of children. We have recruited all consecutive patients aged 0-14 years, admitted for sharp/pointed FB ingestion. Clinical data until hospital discharge were accurately recorded, including both children with esophagogastric FB retention who underwent endoscopic removal and children who were radiologically followed-up till spontaneous FB expulsion. Clinical outcomes were recorded for each patient, with special reference to possible prolonged retention and wall perforation during the intestinal passage. We have enrolled 580 children (males/females: 292/288; age range: 11-180 months; mean age ± standard deviation: 50.5 ± 42 months). Sharp/pointed FBs mainly included fragments of metal 270 of 580 (46.55%) and glass 180 of 580 (31%). FBs were endoscopically removed in 79 of 580 (13.6%) children whereas the remaining FBs passed through the gastrointestinal tract over an overall mean time of 29 hours. No cases of intestinal perforation nor prolonged retention were observed. In 3 of 65 (4.6%) procedures the endoscopist faced an uncomfortable endoscopic removal due to the shape and size of the FB which hampered the retrograde passage through the esophageal sphincters. Our original and extensive data emphasize that accidental ingestion of sharp/pointed FB ingestion is a current issue in pediatric age, especially in toddlers. Metal and glass objects are the most involved FBs and their endoscopic retrieval may not be easy in about 5% of cases. Fortunately, in our pediatric sample no surgical intervention was needed.

Traces of Metal Production in the Mezraa Höyük in The Early Bronze Age

Metal objects and findings that suggest metallurgy activities were discovered in the Early Bronze Age architectural layers of the Mezraa Höyük. Among the finds were two crucible fragments and a casting mould. Analysis of the metal fragments preserved on the crucible parts revealed the presence of arsenical copper. Pins with forms that were well known in the Middle Euphrates Region during the Early Bronze Age make up another group of findings. In analysis, one pin was determined to be an arsenical copper alloy and the other a tin-copper alloy. This data proves that metallurgical activities were present in the second half of the Early Bronze Age and that the alloy arsenical copper was produced.

Lead exposure in American black bears increases with age and big game harvest density

Hunting has multiple consequences for wildlife, and it can be an important source of environmental pollution. Most big game hunters use lead (Pb) ammunition that shed metal fragments in the tissues of harvested animals. These Pb fragments become available to scavengers when hunters discard contaminated slaughter remains in the environment. This exposure route has been extensively studied in avian scavengers, but few studies have investigated Pb exposure from ammunition in mammals. Mammalian scavengers, including American black bears (Ursus americanus), frequently use slaughter remains discarded by hunters. The objective of this study was to investigate whether big game harvest density influenced long-term Pb exposure in American black bears from Quebec, Canada. Our results showed that female black bears had higher tooth Pb concentrations in areas with higher big game harvest densities, but such relationship was not evident in males. We also showed that older bears had higher tooth Pb concentrations compared to younger ones. Overall, our study showed that Pb exposure increases with age in black bears and that some of that Pb likely comes from bullet fragments embedded in slaughter remains discarded by hunters. These results suggest that hunters may drive mammalian scavengers into an evolutionary trap, whereby the long-term benefits of consuming slaughter remains could be negated due to increased Pb exposure.

Quantum Interference in Mixed-Valence Complexes: Tuning Electronic Coupling Through Substituent Effects.

Whilst 2- or 5-OMe groups on the bridging phenylene ring in [{Cp*(dppe)RuC≡C}2 (μ-1,3-C6 H4 )]+ have little influence on the electronic structure of this weakly coupled mixed-valence complex, a 4-OMe substituent enhances ground state electron delocalization, and increases the intensity of the IVCT transition. Vibrational frequency and TDDFT calculations (LH20t-D3(BJ), def2-SVP, COSMO (CH2 Cl2 )) on ([{Cp*(dppe)RuC≡C}2 (μ-1,3-C6 H3 -n-OMe)]+ (n=2, 4, 5) models are in excellent agreement with the experimental results. The stronger ground state coupling is attributed to the change in composition of the β-HOSO brought about by the 4-OMe group, which is ortho or para to each of the metal fragments. The intensity of the IVCT transition increases with the greater overlap of the β-HOSO and β-LUSO, whilst the relative phases of the β-HOSO and β-LUSO in the 4-OMe substituted complex are consistent with predictions of constructive quantum interference from molecular circuit rules.

Synthesis and Characterization of Ir-(κ2-NSi) Species Active toward the Solventless Hydrolysis of HSiMe(OSiMe3)2.

The reaction of [IrH(Cl)(κ2-NSitBu2)(coe)] (1) with 1 equiv of PCy3 (or PHtBu2) gives the species [IrH(Cl)(κ2-NSitBu2)(L)] (L = PCy3, 2a; PHtBu2, 2b), which reacts with 1 equiv of AgOTf to afford [IrH(OTf)(κ2-NSitBu2)(L)] (L = PCy3, 3a and PHtBu2, 3b). Complexes 2a, 2b, 3a, and 3b have been characterized by means of NMR spectroscopy and HR-MS. The solid-state structures of complexes 2a, 2b, and 3a have been determined by X-ray diffraction studies. The reversible coordination of water to 3a, 3b, and 4 to afford the corresponding adduct [IrH(OTf)(κ2-NSitBu2)(L)(H2O)] (L = PCy3, 3a-H2O; PHtBu2, 3b-H2O; coe, 4-H2O) has been demonstrated spectroscopically by NMR studies. The structure of complexes 3b-H2O and 4-H2O have been determined by X-ray diffraction studies. Computational analyses of the interaction between neutral [NSitBu2]• and [Ir(H)L(X)]• fragments in Ir-NSitBu2 species confirm the electron-sharing nature of the Ir-Si bond and the significant role of electrostatics in the interaction between the transition metal fragment and the κ2-NSitBu2 ligand. The activity of Ir-(κ2-NSitBu2) species as catalysts for the hydrolysis of HSiMe(OSiMe3)2 depends on the nature of the ancillary ligands. Thus, while the triflate derivatives are active, the related chloride species show no activity. The best catalytic performance has been obtained when using complexes 3a, with triflate and PCy3 ligands, as a catalyst precursor, which allows the selective obtention of the corresponding silanol.

High-Velocity Metal Fragment: Motion Characteristic and Optimization Design

This present work suggests a charge technique to produce a super high-velocity fragment (≥2350 m/s) using a 30 mm launching system. The steel cylindrical fragments with Brinell hardness HB ≤ 270 are designed according to STANAG 4496 in the experiment, and a test system including interval speed measuring device, pressure measurement and high-speed camera is employed to obtain the information on the velocity, pressure and muzzle field of the fragment. The flame characteristics presents an increasing area, and the fragment escapes the control of the muzzle field when the high-velocity fragment is flying out of the muzzle. Moreover, the projectile sabot can timely be separated from the fragment in the range of the first interval velocity measuring device. Based on this, the mathematic models on the interior ballistic process of the fragment movement are established to analyze the effects of various charge structures on the motion characteristic of the fragment. Comparisons of fragment velocity and chamber pressure of computational results are performed with experimental studies. A reasonable match has been obtained in these comparisons. Further, a discussion on the choice of charge parameters is performed by the optimization design for this super high-velocity fragment.

Neurosurgery during the Greco-Italian War (World War II): the management of war-related head injuries at the Italian field hospital of Sinanaj in Albania.

During the Greco-Italian War (World War II [WWII], 1940-1941), an Italian field hospital was set up in Sinanaj, Albania. The hospital's military surgeons carefully collected information about the characteristics and management of patients with war-related injuries. In 1942, they published a detailed report, with a section dedicated to the management of war-related head injuries. The aim of this report is to analyze that section, to describe the characteristics and neurosurgical management of war-related head injuries, and to depict the status of war neurosurgery in the Royal Italian Army during WWII. The analysis revealed that, during the Greco-Italian War (November 1940-April 1941), 149 patients with war-related head injuries were admitted to the Sinanaj hospital, and 48 patients underwent surgery. Head injuries were caused by bomb fragments in 126 patients, bullets in 5 patients, and other causes (falls from height, vehicle accidents, or rock fragments) in 18 patients. Six patients (12.5%) died after surgery. Before surgery, patients underwent resuscitation with blood transfusions and fluid. Preoperatively, a plain head radiograph was usually acquired to locate metallic and bone fragments. The surgical technique consisted of craniotomy or craniectomy, aggressive debridement of metallic and bone fragments, and watertight dural closure. Surgical drainage, overall aseptic technique, serial spinal taps, and perioperative antibiotics were used to prevent infections. The surgical aims and technique used by the Italian surgeons for the management of head injuries were similar to those of the Allied surgeons during WWII. Operative mortality was also comparable. Although the surgical technique for war-related head injuries has evolved since WWII, many aspects of the technique used by the Italian and Allied surgeons during WWII are still in the standard of care today.

Antibacterial activity and molecular studies of non-symmetric POCOP-Pd(II) pincer complexes derived from 2,4-dihydroxybenzaldehyde (2,4-DHBA)

A series of non-symmetric POCOP-Pd(II) pincer complexes including an aldehyde group in the meta-position of the aromatic pincer-backbone were prepared and characterized. The molecular structure of complex 1-Pd was unambiguously determined by single crystal X-ray diffraction analysis, showing a square-planar geometry around the metal fragment and the presence of the aldehyde functionality at the pincer ligand backbone. The evaluation of the antibacterial activities of complexes 2-Pd and 3-Pd against gram-positive and gram-negative strains was performed. Complex 3-Pd was the most active against S. aureus ATCC 25923 strain with a MIC value of 8 µg∙mL−1. We also determined by molecular docking studies, that pincer complexes 2-Pd and 3-Pd may interact with some key bacterial enzymes such as KPC-2 and PBP2A.

Neurosurgery at Pearl Harbor: Ralph Cloward’s legacy

Ralph B. Cloward (1908-2000) was the sole neurosurgeon present during the Japanese attack on Pearl Harbor on December 7, 1941. Cloward operated on 42 patients in a span of 4 days during the attacks and was awarded a commendation signed by President Franklin D. Roosevelt in 1945 for his wartime efforts. During the attacks, he primarily treated depressed skull fractures and penetrating shrapnel wounds, but he also treated peripheral nerve and spine injuries in the aftermath. His techniques included innovative advancements such as tantalum cranioplasty plates, electromagnets for intracranial metallic fragment removal, and the application of sulfonamide antibiotic powder within cranial wounds, which had been introduced by military medics for gangrene prevention in 1939 and described for penetrating cranial wounds in 1940. Despite the severity of injuries encountered, only 2 soldiers died in the course of Cloward's interventions. As the sole neurosurgeon in the Pacific Theater until 1944, he remained in Honolulu through World War II's duration and gained immense operative experience through his wartime service. Here, the authors review the history of Cloward's remarkable efforts, techniques, injury patterns treated, and legacy.

On the Question of S–S Bond Cleavage of 2,2′-Dithiodipyridine on Selective Ru and Os Platforms. MLCT or Hydride or Solvent Mediated Event

This article deals with the S–S bond scission of the model substrate 2,2′-dithiodipyridine (DTDP) in the presence of a selective set of metal precursors: RuII(acac)2, [RuIICl2(PPh3)3], [RuIIHCl(CO)(PPh3)3], [RuII(H)2(CO)(PPh3)3], [RuII(bpy)2Cl2], [RuII(pap)2Cl2], [OsII(bpy)2Cl2], and [OsII(pap)2Cl2] (acac, acetylacetonate; bpy, 2,2′-bipyridine; pap, 2-phenylazopyridine). This led to the eventual formation of the corresponding mononuclear complexes containing the cleaved pyridine-2-thiolate unit in 1–4/[5]ClO4–[8]ClO4. The formation of the complexes was ascertained by their single-crystal X-ray structures, which also established sterically constrained four-membered chelate (average N1–M–S1 angle of 67.89°) originated from the in situ-generated pyridine-2-thiolate unit. Ruthenium(III)-derived one-electron paramagnetic complexes 1–2 (S = 1/2, magnetic moment/B.M. = 1.82 (1)/1.81(2)) exhibited metal-based anisotropic electron paramagnetic resonance (EPR) (Δg: 1/2 = 0.64/0.93, ⟨g⟩: 1/2 = 2.173/2.189) and a broad 1H nuclear magnetic resonance (NMR) signature due to the contact shift effect. The spectroelectrochemical and electronic structural aspects of the complexes were analyzed experimentally in combination with theoretical calculations of density functional theory (DFT and TD-DFT). The unperturbed feature of DTDP even in refluxing ethanol over a period of 10 h can be attributed to the active participation of the metal fragments in facilitating S–S bond cleavage in 1–4/[5]ClO4–[8]ClO4. It also revealed the following three probable pathways toward S–S bond cleavage of DTDP as a function of metal precursors: (i) the metal-to-ligand charge-transfer (MLCT) (RuII → σ* of DTDP)-driven metal oxidation (RuII → RuIII) process in the case of relatively electron-rich metal fragments {RuII(acac)2} or RuIICl2 in 1 or 2, respectively; (ii) metal hydride-assisted formation of 3 or 4 with the concomitant generation of H2; and (iii) S–S bond reduction with the simultaneous oxidation of the solvent benzyl alcohol to benzaldehyde.

Synthesis and Characterization of Zinc Vanadate Nanostructures for Supercapacitor Applications

A simple hydrothermal approach was used to successfully produce nanostructured Zinc vanadate (Zn3V2O8), which was calcined at 450 ℃. The structural, optical and surface morphological features of calcined Zn3V2O8 nanoparticles were investigated using a variety of analytical techniques. The produced Zn3V2O8 nanoparticles had an orthorhombic crystalline structure, with an average crystallite size of 35.14 nm, according to the X-ray diffraction pattern (XRD). Transmission electron microscopy (TEM) analysis evaluated the spherical shaped Zn3V2O8 nanoparticles. The calcined catalyst was characterized by Fourier Transform-Infrared spectroscopy (FT-IR) analysis to analyse bonding interactions between the metal fragments within the composites. The nanoparticles obtained from hydrothermal synthesis were of size 37.2 nm, and the zeta-potential of nanoparticles was found to be −25.4 mV, indicating excellent dispersion and stability. The spectrophotometer was used to analyse the UV-Vis diffuse reflectance spectra (DRS). Cyclic voltammetry and electrochemical impedance spectroscopy were used to study the electrochemical behavior of Zn3V2O8 nanostructures. The specific capacitance value of the synthesized nanoparticles was 248.5 Fg−1. The active composite material was exploited as an electrode for the Supercapacitor application, and it revealed that synthesized Zn3V2O8 nanoparticles might lead to a possible application for future energy storage technologies.&#x0D; HIGHLIGHTS&#x0D; &#x0D; Zinc vanadate nanostructures have been prepared using easy and economical hydrothermal technique and are explored for supercapacitor application&#x0D; Electrochemical behaviour of zinc vanadate nanostructures were investigated by cyclic voltammetry, electrochemical impedance spectroscopic analysis and galvano static charge discharge analysis&#x0D; This zinc vanadate nanostructures exhibited a maximum specific capacitance of 248.5 F g−1 in the HCl electrolyte&#x0D; It clearly revealed that synthesized nanoparticles may lead to potential application for forthcoming energy storage devices&#x0D; &#x0D; GRAPHICAL ABSTRACT

Implications for food safety of the size and location of fragments of lead shotgun pellets embedded in hunted carcasses of small game animals intended for human consumption.

Carcasses of common pheasants (Phasianus colchicus) killed by hunters using shotguns are widely used or sold in the United Kingdom and elsewhere for human consumption. Almost all of the birds are shot using shotgun pellets composed principally of lead (Pb). Lead shotgun pellets often fragment on impact within the bodies of gamebirds, leaving small lead particles in the meat that are difficult for consumers to detect and remove and from which a greater proportion of lead is likely to be absorbed. Chronic exposure to even low levels of lead is associated with negative health effects in humans and especially in groups particularly vulnerable to the effects of lead, which include young children and pregnant women. Our study used a high-resolution computerised tomography X-ray scanner to locate, in three dimensions, metal fragments embedded within carcasses of eight pheasants sold for human consumption in the UK. Small radio-dense fragments (<2 mm diameter), assumed to be metallic lead, were present in all of the pheasant carcasses examined (mean number: 39 per carcass) and many were too small (<0.1 mm diameter) and too distant from the nearest large shotgun pellet for it to be practical for consumers to detect and remove them without discarding a large proportion of otherwise usable meat. Consumers of carcasses of pheasants killed using lead shotgun ammunition are likely to be exposed to elevated levels of dietary lead, even if careful food preparation is practiced to remove shotgun pellets and the most damaged tissue.

ORAL PIGMENTED LESION: A CASE REPORT

A 67-year-old female patient presented in intraoral examination a darkened spot in the maxilla region above the central incisors, near the bottom of the vestibule, which extended to the hard palate. She reported that, 52 years ago, she had suffered a trauma that resulted in fracture of tooth 21, and a paraendodontic surgery was performed with apicectomy and insertion of metallic material, but there was no success, and the tooth was extracted. Diagnostic hypotheses considered were as follows: extrinsic pigmentation, melanoma, and melanosis by nevus cells. Periapical radiography was performed, but no metallic fragment was found. Then, an incisional biopsy was performed with a final diagnosis of amalgam tattoo. There was no recurrence in 6 months follow-up. It is concluded that, regardless of the extension, location, and nonidentification of a radiopaque fragment on radiographs, the previous clinical history is important for appropriate diagnosis and management.

Impact of the long-time armed conflicts on the ecological safety of industrial objects

&#x0D; &#x0D; &#x0D; The article analyzes the consequences of pollution from industrial enterprises, as well as the risks of disruption of operation and flooding of mines. The armed conflict in the East of Ukraine led to serious environmental consequences – it is the pollution of groundwater, water bodies, air pollution, decommissioning of large areas of arable land, destruction and damage to objects of the nature reserve fund, forest fires, etc. It has been shown that in areas where the armed conflict continues, there has been significant pollution of the environment with chemical toxic substances, metal fragments and heavy metals due to artillery shelling and the use of explosives. As a result, numerous funnels were formed, which mutilated the land and destroyed natural protected areas, flooded mines, built fortifications, ditches, and damaged sewage and water supply networks. Risks associated with damage to communications, businesses and other facilities that pose an increased environmental risk, increase the scale of the negative impact. The problem of flooding of mines and excessive mineralization of waters, which are the part of the production process, is very relevant for both Luhansk and Donetsk regions. Solving this problem requires significant efforts from both the Ukrainian state and international environmental organizations. The main problem is that the mines are located in both controlled and uncontrolled by the Ukrainian government. The fate of coal mines in the territory not controlled by t government of Ukraine is uncertain and requires control by international organizations that are able to conduct monitoring activities. The coal industry in the EU is at «coal-out phase», i. e. at the stage of gradual abandonment of coal mining. First of all, this is dictated by the EU’s course to reach a carbon-free economy by 2050, which means the gradual abandonment of coal generation and the transition to renewable energy sources. And also in accordance with the EU Directive No787 in 2010 On the need to close unprofitable mines.&#x0D; &#x0D; &#x0D;

Kenneth Wade. 13 October 1932—16 March 2014

Much of Ken Wade's scientific career was devoted to developing and exploiting the chemistries of boron, aluminium, gallium and indium (the Group 13 elements). He made significant contributions to both experimental and theoretical aspects of the subject and was a highly regarded teacher and attentive research supervisor. Ken was a modest and self-critical man who had a rare ability to recognize patterns in large chemical and molecular structure data sets and express the resulting generalizations in the form of simple rules that experimental chemists could appreciate and use to predict new compounds. Ken was fascinated by the structures of cluster compounds that are based on regular polyhedral shapes. Cluster molecules generally contain groups of metal atoms linked by metal–metal bonds and located on one or more spherical shells. Since the 1960s they have attracted the attention of both academic and industrial chemists. Understanding and predicting their three-dimensional shapes raised a significant intellectual challenge for chemists. The clusters also attracted attention because they occupy an intermediate position between co-ordination compounds based on a single metal atom and the parent metal, which has an infinite number of linked metal atoms. This provided chemists with a unique opportunity to explore the evolution of their electronic and chemical properties as the cluster size increases. Ken was the first to recognize the electronic relationships connecting closo- , nido- , arachno- and hypho - clusters. These clusters are inter-related by the successive removal of vertices from a regular closo- deltahedron, i.e. a polyhedron with all the faces triangular. His ability to connect the structures of these molecules to the number of valence electrons involved in skeletal bonding represented a significant contribution to chemical bonding theories. Ken communicated his conclusions in very clearly written papers and books. This made the complexities of cluster chemistry amenable to many and especially those who did not have a strong background in quantum chemistry. The skeletal electron counting rules, or Wade's Rules, which Ken pioneered, are now very much part of the fabric of modern cluster chemistry and form an important component of modern undergraduate inorganic chemistry courses. Wade's Rules may be applied to main group and transition metal carbonyl clusters as well as clusters containing both main group and transition metal fragments. Besides providing an accessible entry into cluster chemistry for students, the rules have been used creatively by many leading synthetic chemists to discover new classes of compounds.

Excited States of Metal-Adsorbed Dimethyl Disulfide: A TDDFT Study with Cluster Model.

The optical near field refers to a localized light field near a surface that can induce photochemical phenomena such as dipole-forbidden transitions. Recently, the photodissociation of the S–S bond of dimethyl disulfide (DMDS) was investigated using a scanning tunneling microscope with far- and near-field light. This reaction is thought to be initiated by the lowest-energy highest occupied molecular orbital (HOMO) to lowest unoccupied molecular orbital (LUMO) transition of the DMDS molecule under far-field light. In near-field light, photodissociation proceeds at lower photon energies than in far-field light. To gain insight into the underlying mechanism, we theoretically investigated the excited states of DMDS adsorbed on Cu and Ag surfaces modeled by a tetrahedral 20-atom cluster. The frontier orbitals of the molecule were delocalized by the interaction with the metal, resulting in narrowing of the HOMO–LUMO gap energy. The excited-state distribution was analyzed using the Mulliken population analysis, decomposing molecular orbitals into metal and DMDS fragments. The excited states of the intra-DMDS transitions were found over a wider energy range, but at low energies, their oscillator strengths were negligible, which is consistent with the experimental results. Sparse modeling analysis showed that typical electronic transitions differed between the higher and lower excited states. If these low-lying excited states are efficiently excited by near-field light with different selection rules, the S–S bond dissociation reaction can proceed.

The Use of Bridging Ligand Substituents to Bias the Population of Localized and Delocalized Mixed-Valence Conformers in Solution.

The electronic structure and associated spectroscopic properties of ligand‐bridged, bimetallic ‘mixed‐valence’ complexes of the general form {M}(μ‐B){M+} are dictated by the electronic couplings, and hence orbital overlaps, between the metal centers mediated by the bridge. In the case of complexes such as [{Cp*(dppe)Ru}(μ‐C≡CC6H4C≡C){Ru(dppe)Cp*}]+, the low barrier to rotation of the half‐sandwich metal fragments and the arylene bridge around the acetylene moieties results in population of many energy minima across the conformational energy landscape. Since orbital overlap is also sensitive to the particular mutual orientations of the metal fragment(s) and arylene bridge through a Karplus‐like relationship, the different members of the population range exemplify electronic structures ranging from strongly localized (weakly coupled Robin‐Day Class II) to completely delocalized (Robin‐Day Class III). Here, we use electronic structure calculations with the hybrid density functional BLYP35‐D3 and a continuum solvent model in combination with UV‐vis‐NIR and IR spectroelectrochemical studies to show that the conformational population in complexes [{Cp*(dppe)Ru}(μ‐C≡CArC≡C){Ru(dppe)Cp*]+, and hence the dominant electronic structure, can be biased through the steric and electronic properties of the diethynylarylene (Ar) moiety (Ar=1,4‐C6H4, 1,4‐C6F4, 1,4‐C6H2‐2,5‐Me2, 1,4‐C6H2‐2,5‐(CF3)2, 1,4‐C6H2‐2,5‐iPr2).

Electron transfers’ assessment between stannol ring of triple-decker complexes and M(CO)5 (M = Cr, Mo, W), MnCp(CO)2 and CoCp(CO) metallic fragments: Bonding and energy decomposition analysis

Density functional theory (DFT) calculations using BP86 and B3LYP* functionals have been performed on a series of triple-decker complexes [(M’Cp)2(C4Sn)](R) (M’ = Fe, Ru and R = Cr(CO)5, Mo(CO)5, W(CO)5, MnCp(CO)2 and CoCp(CO)) of 30-MVE (metal valence electrons) count to investigate the electronic structure, the bonding and the energy decomposition. The bonding is evaluated through the interactions between Sn(II) and R metallic fragments. The optimized structures for the considered complexes are comparable to the available X-ray data. The bonding energies have been calculated for all considered systems and their dependence on the nature of the metal cation of the R metallic fragment and its environment has been discussed. The increase of the MVE of the R fragments conducts to a remarkable increase of Sn-metal interactions. The natural charges and the localization of the molecular orbitals have been used to predict the variation of the interactions with the nature of the metal fragment. The σ-donation (L → M) and π-backdonation (L ← M) (L = (M’Cp)2(C4Sn) and M = the metal of the R metallic fragment) are evaluated based on the donor–acceptor electrons transfers showing the strength of the former and the cancellation or partial cancellation of the later. The electrostatic and orbital interaction contributions and the role of σ donor and π acceptor bonding are for a great significance in relationship with the energy decomposition analysis (EDA). The Sn-Metal bonding was revealed to be more ionic than covalent in relationship with the proportion of ΔEelstat and ΔEorb into the total of attractive interactions (ΔEelstat + ΔEorb) and it is well correlated to its bond distance and its Wiberg bond index. The π bonding for Cr(CO)5, Mo(CO)5 and W(CO)5 is weak but not totally suppressed, contrarily to that for MnCp(CO)2 and CoCp(CO) which contributes significantly by about 22% and 26%, into the total orbital interactions, respectively.