Boron rings containing planar octa-and enneacoordinate cobalt, iron and nickel metal elements

Luo, Qian

doi:10.1007/s11426-008-0073-9

Cited by 29 publications

(24 citation statements)

References 67 publications

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“…Indeed, all 3d transition-metal atoms have been tested computationally for the MB n -type hypercoordinate complexes. [18][19][20][21] Two complexes, namely CoB 8 À and FeB 9 À , in which the Co and Fe atoms are trivalent and divalent, respectively, were found to be closed-shell global minima, in agreement with our electronic design principle.We have focused our experimental efforts on transitionmetal-doped boron clusters that involve Group 8 (Fe, Ru, Os) and 9 (Co, Rh, Ir) elements. The experiments were carried out using a PES apparatus equipped with a laser vaporization supersonic cluster source and a magnetic-bottle PES analyzer (see the Experimental Section).…”

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confidence: 80%

Aromatic Metal‐Centered Monocyclic Boron Rings: Co©B₈⁻ and Ru©B₉⁻

et al. 2011

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Bulk boron, which is characterized by 3D cage-like structural features, is a refractory material. [1,2] However, 3D cage structures were suggested to be unstable for small boron clusters, and planar or quasi-planar structures have been proposed instead. [3][4][5] Experimental studies combined with high-level calculations have shown that small boron cluster ions are planar up to at least B 20 À , [6][7][8][9][10] whereas B n + ions have been found to be planar up to n = 16.[11] The chemical bonding in the planar boron clusters has been found to be quite remarkable; [6][7][8][9] in addition to the strong and localized bonding in the circumferences, there are two types of delocalized bonding-the in-plane s and the out-of-plane p bonding, each of which follows the (4 N + 2) Hückel rule for aromaticity. In particular, systems with six s and six p electrons (N = 1) are doubly aromatic, and give rise to highly symmetric planar clusters, such as B 8 2À and B 9 À , which each contain a central B atom and a B 7 and B 8 monocyclic ring, respectively.[6] In the D 7h B 8 2À and D 8h B 9 À molecular wheels, each B atom in the circumference contributes two electrons to the B-B peripheral covalent bonds and one electron to the delocalized bonds, whereas the central B atom contributes all its valence electrons to the delocalized bonds. These novel bonding situations suggest that other atoms with appropriate numbers of valence electrons and sizes may be able to replace the central boron atom to produce MB n -type clusters. [12] Hexagonal, heptagonal, and octagonal CB n -type clusters have been proposed from theoretical calculations as examples of hexa-, hepta-, and octacoordinate planar carbons. [13][14][15] However, photoelectron spectroscopy (PES) studies showed that carbon occupies the peripheral position in such clusters rather than the center, [16,17] because C is more electronegative than B and thus prefers to participate in localized two-center-two-electron (2 c-2 e) s bonding, which is possible only at the circumference of the wheel structure. Transition-metal atoms are better suited for the central position in the MB n clusters, as these metals favor participation in delocalized bonding at the center over localized bonding at the periphery. For an MB n cluster, the electronic requirement for the central atom is x = 12 À n or x = 12 À n À k for an MB n kÀ anion, where x is the valence of the transitionmetal atom M, in order to satisfy the peripheral BÀB s bonding and the s and p Hückel aromaticity for N = 1. Indeed, all 3d transition-metal atoms have been tested computationally for the MB n -type hypercoordinate complexes. [18][19][20][21] Two complexes, namely CoB 8 À and FeB 9 À , in which the Co and Fe atoms are trivalent and divalent, respectively, were found to be closed-shell global minima, in agreement with our electronic design principle.We have focused our experimental efforts on transitionmetal-doped boron clusters that involve Group 8 (Fe, Ru, Os) and 9 (Co, Rh, Ir) elements. The experiments were carried out usi...

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Aromatic Metal‐Centered Monocyclic Boron Rings: Co©B₈⁻ and Ru©B₉⁻

et al. 2011

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“…Apart from carbon, many other planar hypercoordinate main group elements have also been reported, including planar hypercoordinate boron by Wang et al [33] and planar hypercoordinate silicon by Li et al [34]. Very recently, planar hypercoordinate transition metals, e.g., Fe, Co, Ni, Au, Sc and Zn have also been investigated [35][36][37][38][39][40][41][42]. A systematic study of planar hypercoordinate molecules with first row d-block metal atoms in the center of boron rings was carried out in our earlier computational work [43,44].…”

Section: Introductionmentioning

confidence: 99%

MB 8 2− (M = Be, Mg, Ca, Sr, and Ba): Planar octacoordinate alkaline earth metal atoms enclosed by boron rings

2010

Sci. China Chem.

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Complexes involving planar octacoordinate alkaline earth metal atoms in the centers of eight-membered boron rings have been investigated by two density functional theory (DFT) methods. BeB 8 2 with D 8h symmetry is predicted to be stable, both geometrically and electronically, since a good match is achieved between the size of the central beryllium atom and the eight-membered boron ring. By contrast, the other alkaline earth metal atoms cannot be stabilized in the center of a planar eight-membered boron ring because of their large radii. By following the out-of-plane imaginary vibrational frequency, pyramidal C 8v MgB 8 2 , CaB 8 2 , SrB 8 2 , and BaB 8 2 structures are obtained. The presence of delocalized  and  valence molecular orbitals in D 8h BeB 8 2 gives rise to aromaticity, which is reflected by the value of the nucleus-independent chemical shift. The D 8h BeB 8 2 structure is confirmed to be the global minimum on the potential energy surface.density functional theory, octacoordinate, alkaline earth metal, aromatic, molecular orbital

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“…We also presented a universal structural pattern for planar hyper-coordinate Si in B n H 2 Si series [9] . Very recently, Luo proposed planar octa-and ennea-coordinate transition metals in M@B n (M=Fe, Co; n=8, 9) at DFT [10] . Bigger boron rings were even employed to host multiple planar coordinate carbons [11] .…”

Section: Introductionmentioning

confidence: 99%

Planar or quasi-planar octa- and ennea-coordinate aluminum and gallium in boron rings

Guo

Yao

et al. 2009

Sci. China Ser. B-Chem.

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An ab initio theoretical investigation has been performed on planar or quasi-planar octa-and ennea-coordinate Al and Ga centered in X@B 8 − and X@B 9 (X=Al, Ga). These high symmetry molecular wheels all turned out to be true minima of the systems and σ+π double aromatic in nature, similar to the previously characterized D 8h B@B 8 − both electronically and geometrically. Adiabatic and vertical detachment energies of the anions and the ionization potentials of the neutrals have been calculated to aid their eventual experimental identification.planar hyper-coordinate, aluminum, gallium, ab initio, geometry, electronic structure

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Boron rings containing planar octa-and enneacoordinate cobalt, iron and nickel metal elements

Cited by 29 publications

References 67 publications

Aromatic Metal‐Centered Monocyclic Boron Rings: Co©B₈⁻ and Ru©B₉⁻

Aromatic Metal‐Centered Monocyclic Boron Rings: Co©B₈⁻ and Ru©B₉⁻

MB 8 2− (M = Be, Mg, Ca, Sr, and Ba): Planar octacoordinate alkaline earth metal atoms enclosed by boron rings

Planar or quasi-planar octa- and ennea-coordinate aluminum and gallium in boron rings

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Boron rings containing planar octa-and enneacoordinate cobalt, iron and nickel metal elements

Cited by 29 publications

References 67 publications

Aromatic Metal‐Centered Monocyclic Boron Rings: Co©B8− and Ru©B9−

Aromatic Metal‐Centered Monocyclic Boron Rings: Co©B8− and Ru©B9−

MB 8 2− (M = Be, Mg, Ca, Sr, and Ba): Planar octacoordinate alkaline earth metal atoms enclosed by boron rings

Planar or quasi-planar octa- and ennea-coordinate aluminum and gallium in boron rings

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Aromatic Metal‐Centered Monocyclic Boron Rings: Co©B₈⁻ and Ru©B₉⁻

Aromatic Metal‐Centered Monocyclic Boron Rings: Co©B₈⁻ and Ru©B₉⁻