Metal-ligand bonding in 3d sandwich complexes

Clack, Denis W.; Warren, Keith D.

doi:10.1007/3-540-09787-2_1

Cited by 59 publications

(26 citation statements)

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“…Ni@B 12 , Cr@B 16 , Fe@B 16 , and Ni@B 16 lost their D nd symmetry due to the John-Teller effect. The large binding energy (6.16-10.37 eV) and HUMO-LOMO gap (1.14-2.36 eV) indicate the stability of these complexes, except the Fe@B 14 and Ni@B 16 with the low HUMO-LOMO gap of 0.33 eV and 0.84 eV, respectively. The low VEA and high VIP values confirm their stability.…”

Section: Resultsmentioning

confidence: 99%

“…Ni@B 14 and Fe@B 16 are included in the category I. CMO results in Figure 2(a) indicate that there are 12 delocalized orbitals in the Ni@B 14 system, three of which are π orbitals in tangential direction and the rest nine are delocalized in radial direction. The tangential π orbitals are fulfilled with six valence electrons and follow the Huckel's (4n + 2) rule.…”

Section: B Electronic Structuresmentioning

confidence: 99%

“…At first, metallocenes with organic ligands held most of the interests of researchers. [6][7][8][9][10][11][12][13][14][15][16][17][18][19][20][21] However, the reports on the inorganic ligands, which were found have the similar delocalized bondings, had grown rapidly since the beginning of 21st century. In recent years, all-boron clusters were considered as potential new inorganic ligands because of their aromatic and antiaromatic electronic properties similar to the hydrocarbons.…”

Section: Introductionmentioning

confidence: 99%

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Double aromaticity in transition metal centered double-ring boron clusters M@B2n (M = Ti, Cr, Fe, Ni, Zn; n = 6, 7, 8)

Cheng

Yang

2014

The Journal of Chemical Physics

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It is well known that double-ring boron clusters have got the special double aromaticity with delocalized π orbitals in two directions (tangential and radial), which are potential ligands centered by a transition metal. In this article, the transition metal centered double-ring boron clusters M@B2n (M = Ti, Cr, Fe, Ni, Zn; n = 6, 7, 8) are theoretically investigated by density functional theory calculations. These endohedral compounds have also got double aromaticity in both tangential and radial directions. Interestingly, the tangential delocalized π orbitals of boron ligands following the Huckle's (4n + 2) rule do not interact with the central metal, while the radial π orbitals of boron ligands are bonded with the central mental to form spd-π endohedral bonding. The spd-π endohedral bonding follows the 18e-principle in Ni@B14 and Fe@B16. However, due to the flat shape of the compounds, 14e (Cr@B14) and 16e (Ni@B12) can also be electronically very stable where the energy levels of the spd-π orbitals delocalized in z-direction rise up. This intriguing bonding model makes sense in further study of the boron chemistry.

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Section: Resultsmentioning

confidence: 99%

Section: B Electronic Structuresmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

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Double aromaticity in transition metal centered double-ring boron clusters M@B2n (M = Ti, Cr, Fe, Ni, Zn; n = 6, 7, 8)

Cheng

Yang

2014

The Journal of Chemical Physics

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“…25 Therefore, the wave functions ob tained from calculations were additionally analyzed in the framework of the "Atoms in molecules" theory 26 (Table 2). In this case, the atomic charges are calculated by integrat ing the electron density over atomic basins confined by the zero flux surfaces in the vector field of the electron density gradient ∇ρ(r)•n(r) = 0 (∇ρ(r)= i∂ρ/∂x + j∂ρ/∂y + k∂ρ/∂z is the vector of the electron density (ρ) gradient and n(r) is the ort normal to the surface).…”

Section: Resultsmentioning

confidence: 99%

Electronic structures of mixed sandwich ansa-complexes of chromium as studied by gas-phase absorption spectroscopy and quantum chemistry

et al. 2009

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Gas phase electronic absorption spectra of ansa (cycloheptatrienylcyclopentadienyl) chromium complexes with silicon and germanium containing bridges were recorded for the first time. The spectrum of the -(SiMe 2 ) 2 -bridged compound exhibits a Rydberg structure arising from the transitions originating at HOMO. Shortening of the bridge causes the Rydberg bands to broaden beyond detection. Density functional calculations were performed to investi gate the electron density distribution in neutral complexes and the corresponding cations. An increase in the angle between the carbocycles on going from the -(SiMe 2 ) 2 -bridged com pound to the -SiMe 2 -and -GeMe 2 -bridged complexes was shown to cause substantial changes in the composition and energies of the HOMO and Rydberg orbitals. Delocalization of the HOMO in the -SiMe 2 -and -GeMe 2 -bridged molecules leads to broadening of the Rydberg bands in the gas phase spectra.Since the discovery of ferrocene, 1,2 sandwich organo metallic compounds have attracted increased interest ow ing to their structural features and properties. A unique property of such systems consists in manifestation of the Rydberg transitions in the electronic absorption spectra (EAS). Sandwich systems are still the only class of metal complexes whose gas phase EAS exhibit clearly defined Rydberg bands. 3 Usually, these bands originate from tran sitions of an electron from a non bonding MO (almost "pure" metal d z2 orbital) to the Rydberg s, p, and d levels of the molecule. Frequencies of the higher members of the series formed by such transitions are described by the known Rydberg formulawhere ν n is the frequency of the member of the series, n is the principal quantum number, I is the ionization potential (IP) equal to the energy of detachment of an electron from the d z2 orbital, R is the Rydberg constant (109737 cm -1 ), δ is the quantum defect, n* is the effective principal quan tum number, T is the term value equal to the energy of the interaction between the Rydberg electron and the cation core. A characteristic feature of the Rydberg orbitals is their diffuse character; as a consequence, in condensed media with low electronic mobility the Rydberg bands are strongly broadened up to complete disappearance. 4 In this connection, to detect the Rydberg transitions, one should compare the EAS of gaseous compounds and their solutions. Among the metal complexes studied to date, the Ryd berg bands are most pronounced in the absorption spectra of the complex (η 6 C 6 H 6 ) 2 Cr (see Ref. 5) and its isoelec tronic analog (η 7 C 7 H 7 )(η 5 C 5 H 5 )Cr (1) 6 where the vi bronic structure of electronic transitions is observed. The Rydberg structure in the spectra of substituted derivatives of (η 6 C 6 H 6 ) 2 Cr is sensitive to the nature and mutual po sition of substituents; this characterizes the changes in the molecular symmetry, degree of localization of the HOMO, and the character of configuration interactions in the sand wich molecule. 5 Substituted derivatives of (η 7 C 7 H 7 ) (η 5 C 5 H 5 )Cr...

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“…Cyclopentadienyl benzene manganese 4 is the remaining member in the isoelectronic series 2->3->4 and belongs to the class of mixed sandwich compounds that have been studied in large detail in the recent years [40][41][42][43]. As the X-ray structure of 4 is yet unknown we have extrapolated geometrical parameters from related organometallic manganese complexes [44].…”

Section: D5d Aig A2g Eig E2g Aiu A2u Eiu E2umentioning

confidence: 99%

The Electronic Structure of Closed Shell Metallocenes in the Ground State and in the Cationic Hole-States

Böhm

1982

Zeitschrift Für Naturforschung A

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The electronic structure of tne closed shell metallocenes bis(7r-cyclopentadienyl)magnesium (1), bisbenzene chromium (2), ferrocene (3) and cyclopentadienyl benzene manganese (4) has been studied in the ground state as well as in the low-lying cationic states. The computational framework is a semiempirical INDO Hamiltonian, the theoretical framework for the investigation of the cationic hole-states is the Green's function method. The calculated ionization energies are compared with the photoelectron (PE) spectra of the four closed shell metallocenes. The interrelation between theoretically determined reorganization energies and the localization properties of the orbital wave functions or the nature of the transition metal center is analyzed. General rules concerning the validity of Koopman's theorem in transition metal complexes are formulated.

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Metal-ligand bonding in 3d sandwich complexes

Cited by 59 publications

References 70 publications

Double aromaticity in transition metal centered double-ring boron clusters M@B2n (M = Ti, Cr, Fe, Ni, Zn; n = 6, 7, 8)

Double aromaticity in transition metal centered double-ring boron clusters M@B2n (M = Ti, Cr, Fe, Ni, Zn; n = 6, 7, 8)

Electronic structures of mixed sandwich ansa-complexes of chromium as studied by gas-phase absorption spectroscopy and quantum chemistry

The Electronic Structure of Closed Shell Metallocenes in the Ground State and in the Cationic Hole-States

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