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1.
Sudip Pan Said Jalife R. Mahesh Kumar Dr. Venkatesan Subramanian Prof. Gabriel Merino Prof. Pratim K. Chattaraj 《Chemphyschem》2013,14(11):2511-2517
The noble gas binding ability of CN3Be3+ clusters was assessed both by ab intio and density functional studies. The global minimum structure of the CN3Be3+ cluster binds with four noble‐gas (NG) atoms, in which the Be atoms are acting as active centers. The electron transfer from the noble gas to the Be atom plays a key role in binding. The dissociation energy of the Be? NG bond gradually increases from He to Rn, maintaining the periodic trend. The HOMO–LUMO gap, an indicator for stability, gives additional insight into these NG‐bound clusters. The temperature at which the NG‐binding process is thermodynamically feasible was identified. In addition, we investigated the stability of two new neutral NG compounds, (NG)BeSe and (NG)BeTe, and found them to be suitable candidates to be detected experimentally such as (NG)BeO and (NG)BeS. The dissociation energies of the Be? NG bond in monocationic analogues of (NG)BeY (Y=O, S, Se, Te) were found to be larger than in the corresponding neutral counter‐parts. Finally, the higher the positive charge on the Be atoms, the higher the dissociation energy for the Be? NG bond becomes. 相似文献
2.
Stefano Borocci Nicoletta Bronzolino Felice Grandinetti 《Helvetica chimica acta》2007,90(7):1335-1352
Ab initio calculations at the MP2 level of theory disclose the conceivable existence of neutral complexes containing four or five distinct noble gases (Ng) each bound to a distinct Be‐atom. These multicenter polynuclear Ng molecules are formally obtained by replacing the H‐atoms of CH4 and but‐2‐yne with ? NBeNg moieties, which behave as independent monovalent ‘functional groups’. Our investigated complexes include the five homotetranuclear [C(NBeNg)4] complexes 1 – 5 (Ng=He? Xe), the five heterotetranuclear complexes [CN4Be4(He)(Ne)(Ar)(Kr)] ( 6 ), [CN4Be4(He)(Ne)(Ar)(Xe)] ( 7 ), [CN4Be4(He)(Ne)(Kr)(Xe)] ( 8 ), [CN4Be4(He)(Ar)(Kr)(Xe)] ( 9 ), and [CN4Be4(Ne)(Ar)(Kr)(Xe)] ( 10 ), and the heteropentanuclear complex [HC4N5Be5(He)(Ne)(Ar)(Kr)(Xe)] ( 11 ). We also investigated the five model complexes [H3CNBeNg] (Ng=He? Xe) containing a single ? NBeNg moiety. The geometries and vibrational frequencies of all these species, invariably characterized as minimum‐energy structures, were computed at the MP2(full)/6‐31G(d,p)/SDD level of theory, and their stability with respect to the loss of the various Ng‐atoms was evaluated by single‐point calculations at the MP2(full)/6‐311G(d)/SDD level of theory. The beryllium‐Ng binding energies range from ca. 17 (Ng=He) to ca. 63 (Ng=Xe) kJ/mol, and the results of natural‐bond‐orbital (NBO) and atoms‐in‐molecules (AIM) analysis reveal that the Be? Ng interaction is essentially electrostatic for helium, neon, argon, and krypton, and has probably a small covalent contribution for xenon. 相似文献
3.
Sudip Pan Diego Moreno Prof. Gabriel Merino Prof. Pratim K. Chattaraj 《Chemphyschem》2014,15(16):3554-3564
The stability of noble gas (Ng)‐bound SiH3+ clusters is explored by ab initio computations. Owing to a high positive charge (+1.53 e?), the Si center of SiH3+ can bind two Ng atoms. However, the Si?Ng dissociation energy for the first Ng atom is considerably larger than that for the second one. As we go down group 18, the dissociation energy gradually increases, and the largest value is observed for the case of Rn. For NgSiH3+ clusters, the Ar–Rn dissociation processes are endergonic at room temperature. For He and Ne, a much lower temperature is required for it to be viable. The formation of Ng2SiH3+ clusters is also feasible, particularly for the heavier members and at low temperature. To shed light on the nature of Si?Ng bonding, natural population analysis, Wiberg bond indices computations, electron‐density analysis, and energy‐decomposition analysis were performed. Electron transfer from the Ng centers to the electropositive Si center occurs only to a small extent for the lighter Ng atoms and to a somewhat greater extent for the heavier analogues. The Si?Xe/Rn bonds can be termed covalent bonds, whereas the Si?He/Ne bonds are noncovalent. The Si?Ar/Kr bonds possess some degree of covalent character, as they are borderline cases. Contributions from polarization and charge transfer and exchange are key terms in forming Si?Ng bonds. We also studied the effect of substituting the H atoms of SiH3+ by halide groups (?X) on the Ng binding ability. SiF3+ showed enhanced Ng binding ability, whereas SiCl3+ and SiBr3+ showed a lower ability to bind Ng than SiH3+. A compromise originates from the dual play of the inductive effect of the ?X groups and X→Si π backbonding (pz–pz interaction). 相似文献
4.
A noble interaction: An assessment of noble gas binding ability of metal oxides (metal = Cu,Ag, Au)
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Sudip Pan Ranajit Saha Anand Kumar Ashutosh Gupta Gabriel Merino Pratim K. Chattaraj 《International journal of quantum chemistry》2016,116(13):1016-1024
An in silico study is performed on the structure and the stability of noble gas (Ng) bound MO complexes (M = Cu, Ag, Au). To understand the stability of these Ng bound complexes, dissociation energies, dissociation enthalpy, and dissociation free energy change are computed. The stability of NgMO is also compared with that of the experimentally detected NgMX (X= F, Cl, Br). It is found that MO has lower Ng binding ability than that of MX. All the dissociation processes producing Ng and MO are endothermic in nature and for the Kr‐Rn bound MO (M = Cu, Au), and Xe and Rn bound AgO cases, the corresponding dissociation processes are turned out to be endergonic in nature at standard state. The Wiberg bond indices of Ng? M bonds and Ng→M electron transfer gradually increase from Ar to Rn and for the same Ng they follow the order of NgAuO > NgCuO > NgAgO. Energy decomposition analysis shows that the Ng? M bonds in NgMO are partly covalent and partly electrostatic in nature. Electron density analysis further highlights the partial covalent character in Ng? M bonds. © 2016 Wiley Periodicals, Inc. 相似文献
5.
Transmission electron microscopy and diffraction have been used to examine structural aspects of phases along the BeSiN2Be3N2 tie line of the BeSiON system. Electron diffraction experiments are found to substantiate previous X-ray evidence for the derived structures of BeSiN2, β-Be3N2, and α-Be3N2 and the presence of a number of long-period superstructures at intermediate compositions. Real space observations using direct fringe and structure imaging techniques have been made and are in agreement with the 15R polytype structure derived from X-ray diffraction data. This structure is composed of coherent intergrowths of BeSiN2 and β-Be3N2. Further observations made on a nonstoichiometric BeSiN2 sample suggest that the polytypes may be described in terms of a regularly faulted BeSiN2 structure. Each fault changes the coordination of tetrahedral sites from base sharing to edge sharing in the fault, allowing excess beryllium atoms to be accommodated in the close-packed nitrogen lattice. For larger deviations from the BeSiN2 stoichiometric composition, a higher density of faults occur which interact to form ordered arrangements and the observed polytype structures. The present observations establish that polytypism in the BeSiN system is related to the general phenomenon of crystallographic shear as observed in other complex oxide and ceramic systems. It is suggested that similar faulting may account for the polytype structures in other sialon systems. 相似文献
6.
Lakhya Jyoti Mazumder Rohan Sharma Farnaz Yashmin Pankaz Kumar Sharma 《Journal of computational chemistry》2023,44(4):644-655
Quantum chemical calculations were carried out to investigate the nature of the bonding between a neutral Be3 ring and noble gas atom. Electronic structure calculation for these complexes was carried out at different computational levels in association with natural bond orbital, quantum theory of atoms in molecules, electron localization function, symmetry adapted perturbation theory, and molecular electrostatic potential surface analysis of Be3 complexes. The Be atoms in the Be3 moiety are chemically bonded to one another, with the Be Be bond dissociation energy being ~125 kJ mol−1. The Be3 ring interacts with the noble gases through non-covalent interactions. The binding energies of the noble gas atoms with the Be3 ring increases with increase in their atomic number. The non-covalent interaction index, density overlap region indicator and independent gradient model analyses reveal the presence of non-covalent inter-fragment interactions in the complexes. Energy decomposition analysis reveals that dispersion plays the major role towards stabilizing these systems. 相似文献
7.
《International journal of quantum chemistry》2018,118(5)
Ab initio and density functional theory‐based calculations are performed to study the structure, stability, and nature of bonding of superhalogen‐supported noble gas (Ng) compounds of the type HNgY where (Ng = Ar‐Rn; Y = BeF3). Here, BeF3 acts as the superhalogen. Calculations show that the HNgBeF3 spontaneously dissociates into product following the dissociation channels: HNgBeF3 → HBeF3 + Ng and HNgBeF3 → Ng + HF + BeF2. The transition states are optimized and the energy barriers are computed to show the metastable behavior of HNgBeF3. HNgBeF3 molecules are kinetically stable with respect to the first dissociation process having energy barriers of 1.0, 5.0, 10.6, and 13.9 kcal/mol for Ar, Kr, Xe, and Rn analogues, respectively, at CCSD(T)/Aug‐cc‐pVTZ level. These calculations suggest that the HXeBeF3 and HRnBeF3 can be shown to be stable up to ∼100 K temperature with a half‐life of ∼102 seconds. The nature of H Ng and two different types of Ng F bonds in HNgBeF3 molecules is explored through the natural bond orbital and electron density analyses. The large Wiberg bond index (WBI) values for the H Ng bond indicate the formation of almost a single bond in between H‐atoms and Ng‐atoms, whereas small WBI values for the two Ng F bonds indicate a noncovalent interaction in between them. The electron density analysis further supports the covalency of the H Ng bond and noncovalent interaction in the two Ng F bonds in HNgBeF3. 相似文献
8.
Using CALYPSO method to search new structures of neutral and anionic beryllium-doped magnesium clusters followed by density functional theory (DFT) calculations, an extensive study of the structures, electronic and spectral properties of Be2MgnQ (Q = 0, −1; n = 2–11) clusters is performed. Based on the structural optimization, it is found that the Be2MgnQ (Q = 0, −1) clusters are shown by tetrahedral-based geometries at n = 2–6 and tower-like-based geometries at n = 7–11. The calculations of stability indicate that Be2Mg5Q=0, Be2Mg5Q=−1, and Be2Mg8Q=−1 clusters are “magic” clusters with high stability. The NCP shows that the charges are transferred from Mg atoms to Be atoms. The s- and p-orbitals interactions of Mg and Be atoms are main responsible for their NEC. In particular, chemical bond analysis including molecular orbitals (MOs) and chemical bonding composition for magic clusters to further study their stability. The results confirmed that the high stability of these clusters is due to the interactions between the Be atom and the Mg5 or Mg8 host. Finally, theoretical calculations of infrared and Raman spectra of the ground state of Be2MgnQ (Q = 0, −1; n = 1–11) clusters were performed, which will be absolutely useful for future experiments to identify these clusters. 相似文献
9.
Eva Vos Dr. M. Merced Montero-Campillo Dr. Inés Corral Prof. Manuel Yáñez Prof. Ibon Alkorta Prof. José Elguero 《Chemphyschem》2020,21(24):2701-2708
Isolated Be2 is a typical example of a weakly bound system, but interaction with other systems may give rise to surprising bonding features. The interactions between Be2 and a set of selected neutral CnHn (n=2–8) π-systems have been analyzed through the use of G4 and G4MP2 ab initio methods, along with multireference CASPT2//CASPT2 calculations. Our results systematically show that the CnHn−Be2−CnHn clusters formed are always very stable. However, the nature of this interaction is completely different when the π-system involved is a closed shell species (n=2, 4, 6, 8), or a radical (n=3, 5, 7). In the first case, the interaction does not occur with the π-system as a whole, but with specific C centers yielding rather polar but strong C−Be bonds. Nonetheless, although the Be−Be distances in these complexes are similar to the ones in compounds with ultra-strong Be−Be bonds, a close examination of their electron density distribution reveals that no Be−Be bonds exist. The situation is totally different when the interaction involves two π-radicals, CnHn−Be2−CnHn (n=3, 5, 7). In these cases, a strong Be−Be bond is formed. Indeed, even though Be is electron deficient, the Be2 moiety behaves as an efficient electron donor towards the two π-radicals, so that the different CnHn−Be2−CnHn (n=3, 5, 7) clusters are the result of the interaction between Be22+ and two L− anions. The characteristics of these two scenarios do not change when dealing with bicyclic π-compounds, such as naphthalene and pentalene, because the interaction with the Be2 moiety is localized on one of the unsaturated cycles, the other being almost a spectator. 相似文献
10.
Boron forms a rich variety of low‐dimensional nanosystems, including the newly discovered helix Be6B102? ( 1 ) and Be6B11? ( 2 ) clusters. We report herein on the elucidation of chemical bonding in clusters 1 / 2 , using the modern quantum chemistry tools of canonical molecular orbital analyses and adaptive natural density partitioning (AdNDP). It is shown that clusters 1 / 2 contain a chiral helix Be2B10Be2 or Be2B11Be2 skeleton with a total of 11 and 12 segments, respectively, which effectively curve into “helical pseudo rings” and chemically consist of two “quasicircles” as defined by their anchoring Be centers. The helix skeleton is connected via Lewis‐type B?B and Be?B?Be σ bonds, being further stabilized by island π/σ bonds and a loose π bond at the junction. The Be6 component in 1 / 2 assumes a distorted prism shape only physically, and it is fragmented into four parts: two terminal Be2 dimers and two isolated Be centers. A Be2 dimer at the far end manages to bend over and cap a quasicircle from one side of B plane. Consequently, each quasicircle of a helical pseudo ring is capped from opposite sides by two Be2/Be units, facilitating intramolecular charge‐transfers of 5 electrons from Be to B. Overall, the folding of B helix involves as many as 10 electrons. The enormous electrostatics offers the ultimate driving forces for B helix formation. 相似文献
11.
《Ceramurgia International》1979,5(3):101-104
Phase equilibria studies in parts of the system Si, Al, Be/C, N were carried out at 1760 and 1860°C. In the carbide system Al4C3SiCBe2C seven new compounds were found and characterized by their chemical composition and crystal symmetry. In the nitride system AlNSi2N4Be2N2 a solid solution between AlN and BeSiN2 was found to exist besides the already known compounds. The carbonitride system showed solid solution between α-Al4SiC4 and α-Al5C3N. Furthermore the compound AlN · SiC · Al4C3 was found to exist. 相似文献
12.
The electronic stucture of Bel, Mgm and Can ( 1? 7, m and n ? 5) metal clusters has been investigated by means of an ab initio pseudopotential method followed by multireference double-excitation configuration interaction (PP MRD CI). Two completely different situations arise on going from Be to heavier alkaline metals. The sp hybridization, which is effective in the Be case, completely disappears when aggregates of Mg and Ca are considered. The potential energy curves relative to Be, Mg and Ca clusters exhibit a very shallow minimum at large distances while a second deeper minimum is characteristic of some Be clusters. This inner minimum is generated by the large interaction of atomic p orbitals at an internuclear separation close to the BeBe distance present in the Be crystal. The bond in Be clusters largely depends on the geometrical arrangement which directly influences the possible sp hybridisation. Very small Be planar structures are always less favored with respect to clusters containing the tetrahedral unit as a part of the whole structure. However, this situation is changed when larger planar clusters are considered, and the highest binding energy per atom (12.0 kcal/mole) from all clusters considered in this work was found for the triplet ground state of the planar Be7(D6h) cluster. 相似文献
13.
Ultrashort Beryllium−Beryllium Distances Rivalling Those of Metal−Metal Quintuple Bonds Between Transition Metals
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Dr. Caixia Yuan Xue‐Feng Zhao Prof. Dr. Yan‐Bo Wu Prof. Dr. Xiaotai Wang 《Angewandte Chemie (International ed. in English)》2016,55(50):15651-15655
Chemical bonding is at the heart of chemistry. Recent work on high bond orders between homonuclear transition metal atoms has led to ultrashort metal?metal (TM?TM) distances defined as dM?M<1.900 Å. The present work is a computational design and characterization of novel main group species containing ultrashort metal?metal distances (1.728–1.866 Å) between two beryllium atoms in different molecular environments, including a rhombic Be2X2 (X=C, N) core, a vertical Be?Be axis in a 3D molecular star, and a horizontal Be?Be axis supported by N‐heterocyclic carbene (NHC) ligands. The ultrashort Be?Be distances are achieved by affixing bridging atoms to attract the beryllium atoms electrostatically or covalently. Among these species are five global minima and one chemically viable diberyllium complex, which provide potential targets for experimental realization. 相似文献
14.
《Chemical physics》1987,116(2):193-202
Hydrated Be2+ ions [Be(H2O)n]2+, n = 1−4 and 6, were examined theoretically. The structure of the hydrated ions was determined and the hydration energy estimated with and without electron correlation. The bond between the Be2+ ion and the oxygen of water is very strong and has the nature of a dative bond. The non-additivity of the binding energy is so profound that without taking it into account the structure and dynamics of Be2+ ions cannot be explained. The hydration number in water is found to be 4. The fifth and sixth water molecules prefer forming the second coordination shell to the Be2+ ion. The result is in agreement with X-ray analysis of the aqueous solution, but not with a recent molecular dynamics simulation. In addition, the harmonic vibrational frequencies for the complexes are evaluated and compared with some experiments. 相似文献
15.
Alan Leone de Araujo Oliveira Mônica de Abreu Silva Fernando Pirani Luiz Guilherme Machado de Macedo Ricardo Gargano 《International journal of quantum chemistry》2020,120(16):e26266
In this work, some basic features of the intermolecular bond in gas phase H2S-Ng complexes (Ng = He, Ne, Ar, Kr, Xe, and Rn) have been investigated in detail, coupling information from scattering experiments with results of quantum chemical calculations at the CCSD(T)/aug-cc-pVTZ level. Spectroscopic constants, rotovibrational energies, and lifetime as a function of temperature have been evaluated for the complete family of H2S-Ng systems, and an extensive study of involved intermolecular interactions has been performed. In particular, their nature has been characterized by exploiting Atoms-In-Molecules (AIM), Non-Covalent Interactions (NCI), Symmetry-Adapted Perturbation Theory (SAPT), and Charge Displacement (CD) methods, and it was found that all complexes are bound essentially by near-isotropic van der Waals forces, perturbed by weak-stabilizing charge (electron) transfer contributions. Obtained results also show that these additional contributions increase from He up to Rn, providing an appreciable chemical-stabilizing effect of the noncovalent intermolecular bond for H2S-heavier Ng systems. 相似文献
16.
Stefano Leoni Rainer Niewa Lev Akselrud Yurii Prots Walter Schnelle Tahsin Gksuc Mehmet Cetinkol Mehmet Somer Rüdiger Kniep 《无机化学与普通化学杂志》2005,631(10):1818-1824
Ba[Be2N2] was prepared as a yellow‐green microcrystalline powder by reaction of Ba2N with Be3N2 under nitrogen atmosphere. The crystal structure Rietfeld refinements (space group I4/mcm, a = 566.46(5) pm, c = 839.42(9) pm, Rint = 4.73 %, Rprof = 9.16 %) reveal the compound to crystallize as an isotype of the nitridoberyllates A[Be2N2] (A = Ca, Sr) consisting of planar 4.82 nets of mutually trigonal planar coordinated Be and N species. Averaged magnetic susceptibility values for the anion [(Be2N2)2?] determined from measurements on A[Be2N2] with A = Mg, Ca, Ba allow to derive a diamagnetic increment for N3? χdia = (?13±1stat.) · 10?6emu mol?1. Colorless Ba3[Be5O8] was first obtained as an oxidation product of Ba[Be2N2] in air. The crystal structure was solved and refined from single crystal X‐ray diffaction data (space group Pnma, a = 942.9(1) pm, b = 1163.47(7) pm, c = 742.1(1) pm, R1 = 2.99 %, wR2 = 7.15 %) and contains infinite rods of Be in trigonal planar, tetrahedral and 3 + 1 coordination by O. The crystal structure is discussed in context with other known oxoberyllates. Electronic structure calculations and electron localization function diagrams for both compounds support the classification as nitrido‐ and oxoberyllate, respectively. 相似文献
17.
Shahnaz S. Rohman Chayanika Kashyap Sabnam S. Ullah Dr. Ankur K. Guha Lakhya J. Mazumder Dr. Pankaz. K. Sharma 《Chemphyschem》2019,20(4):516-518
Metal-metal triple bonds featuring s-block element have not been reported until now. Only Be−Be double bonds between have been predicted theoretically based on the intuitive electron donation from four s1 type electron-donating ligands. Herein, we theoretically predicted a novel species featuring a Be−Be triple bond in the Li6Be2 molecule. The molecule was found to be thermodynamically stable. The presence of the triple bond was confirmed by adaptive natural density partitioning (AdNDP), electron localization function (ELF), and atoms in molecules (AIM) analyses. Moreover, the mechanical strength of the Be−Be triple bond was analyzed by using compliance matrix, pointing towards its ultra-weak nature. 相似文献
18.
Peter N. Ascik René Rugango Dr. Andrew C. Simmonett Katherine R. Compaan Prof. Henry F. Schaefer III 《Chemphyschem》2012,13(5):1255-1260
Recent high‐resolution spectroscopic studies by Merritt, Bondybey, and Heaven (Science 2009 , 324, 1548) have heightened the anticipation that small beryllium clusters will soon be observed in the laboratory. Beryllium clusters are important discrete models for the theoretical study of metals. The trigonal bipyramidal Be5 molecule is studied using high‐level coupled cluster methods. We obtain the optimized geometry, atomization and dissociation energies, and vibrational frequencies. The c~CCSDT(Q) method is employed to compute the atomization and dissociation energies. In this approach, complete basis set (CBS) extrapolations at the CCSD(T) level of theory are combined with an additive correction for the effect of iterative triple and perturbative quadruple excitations. Harmonic vibrational frequencies are obtained using analytic gradients computed at the CCSD(T) level of theory. We report an atomization energy of 129.6 kcal mol?1 at the trigonal bipyramid global minimum geometry. The Be5→Be4+Be dissociation energy is predicted to be 39.5 kcal mol?1. The analogous dissociation energies for the smaller beryllium clusters are 64.0 kcal mol?1 (Be4→Be3+Be), 24.2 kcal mol?1 (Be3→Be2+Be), and 2.7 kcal mol?1 (Be2→Be+Be). The trigonal bipyramidal Be5 structure has an equatorial–equatorial bond length of 2.000 Å and an axial–equatorial distance of 2.060 Å. Harmonic frequencies of 730, 611, 456, 583, 488, and 338 cm?1 are obtained at the CCSD(T)/cc‐pCVQZ level of theory. Quadruple excitations are found to make noticeable contributions to the energetics of the pentamer, which exhibits a significant level of static correlation. 相似文献
19.
Ranajit Saha Sudip Pan Gabriel Merino Pratim K. Chattaraj 《Angewandte Chemie (Weinheim an der Bergstrasse, Germany)》2019,131(25):8460-8465
Is it possible to facilitate the formation of a genuine Be?Be or Mg?Mg single bond for the E2 species while it is in its neutral state? So far, (NHCR)Be?Be(NHCR) (R=H, Me, Ph) have been reported where Be2 is in 1Δg excited state imposing a formal Be?Be bond order of two. Herein, we present the formation of a single E?E (E=Be, Mg) covalent bond in E2(NHBMe)2 (E=Be, Mg; NHBMe=(HCNMe)2B) complexes where E2 is in 3∑u+ excited state having (nσg+)2(nσu+)1((n+1)σg+)1 (n=2 for Be and n=4 for Mg) valence electron configuration and it forms electron‐shared bonding with two NHBMe radicals. The effects of bonding with nσu+ and (n+1)σg+ orbitals will cancel each other, providing the former E?E bond order as one. Be2(NHBMe)2 complex is thermochemically stable with respect to possible dissociation channels at room temperature, whereas the two exergonic channels, Mg2(NHBMe)2 → Mg + Mg(NHBMe)2 and Mg2(NHBMe)2 → Mg2 + (NHBMe)2, are kinetically inhibited by a free energy barrier of 15.7 and 18.7 kcal mol?1, respectively, which would likely to be further enhanced in cases of bulkier substituents attached to the NHB ligands. Therefore, the title complexes are first viable systems which feature a neutral E2 moiety with a single E?E covalent bond. 相似文献
20.
Ranajit Saha Sudip Pan Gabriel Merino Pratim K. Chattaraj 《Angewandte Chemie (International ed. in English)》2019,58(25):8372-8377
Is it possible to facilitate the formation of a genuine Be?Be or Mg?Mg single bond for the E2 species while it is in its neutral state? So far, (NHCR)Be?Be(NHCR) (R=H, Me, Ph) have been reported where Be2 is in 1Δg excited state imposing a formal Be?Be bond order of two. Herein, we present the formation of a single E?E (E=Be, Mg) covalent bond in E2(NHBMe)2 (E=Be, Mg; NHBMe=(HCNMe)2B) complexes where E2 is in 3∑u+ excited state having (nσg+)2(nσu+)1((n+1)σg+)1 (n=2 for Be and n=4 for Mg) valence electron configuration and it forms electron‐shared bonding with two NHBMe radicals. The effects of bonding with nσu+ and (n+1)σg+ orbitals will cancel each other, providing the former E?E bond order as one. Be2(NHBMe)2 complex is thermochemically stable with respect to possible dissociation channels at room temperature, whereas the two exergonic channels, Mg2(NHBMe)2 → Mg + Mg(NHBMe)2 and Mg2(NHBMe)2 → Mg2 + (NHBMe)2, are kinetically inhibited by a free energy barrier of 15.7 and 18.7 kcal mol?1, respectively, which would likely to be further enhanced in cases of bulkier substituents attached to the NHB ligands. Therefore, the title complexes are first viable systems which feature a neutral E2 moiety with a single E?E covalent bond. 相似文献