Bonding capabilities of transition metal carbonyl fragments

Elian, M.; Hoffmann, Roald

doi:10.1021/ic50147a021

Cited by 552 publications

(254 citation statements)

References 18 publications

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“…This difference was attributed to significant contributions from six-coordinate structures (B) in the case of conjugated dienes and the relative unimportance of such contributions in complexes with nonconjugated dienes. Our results suggest that, in contrast to the general accepted bonding description for butadiene iron tricarbonyl (25,26) back-bonding between filled metal d orbitals and the LUMO (n3*) of the diene is an unimportant component of the ligand-metal bonding in tricarbonylferrole iron tricarbonyl derivatives. For the tricarbonylferrole ligand there is good evidence from X-ray structural data for multiple bonding in the Fe-C bonds of the ferrole ring (14).Thus these bonds are 1.94-1.95 A compared to 2.08-2.12 A expected for the sum of the covalent radii of iron and carbon.…”

Section: C Nuclear Magnetic Resonance Spectra and Fluxional Behaviourcontrasting

confidence: 75%

Tricarbonylferrole iron tricarbonyl derivatives: formation from thiophenes and iron atoms in a CO atmosphere and fluxional behaviour

Chivers¹,

Timms²

1977

Can. J. Chem.

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TRISTRAM CHIVERS and PETER L. TIMMS. Can. J. Chem. 55,3509 (1977).Co-condensation of metal atoms (Cr, Fe) with thiophenes R 'SARI (R = R r = H, Me; R = H, R' = Me) at -196°C leads to desulphurization of the thiophene. Warm-up of the iron-thiophene co-condensate in a CO atmosphere produces derivatives of tricarbonylferrole iron tricarbonyl, C4H2RR'Fe2(C0)6. 13C nmr studies of these complexes show that the tricarbonyl ferrole unit is static from -95°C to + 60°C, while the R -F~( C O )~ group exhibits fluxional behaviour. Addition of dienes or Me3P in hexane to the iron-thiophene co-condensate at -196°C yields thermally unstable red solutions on melting.TRISTRAM CHIVERS et PETER L. TIMMS. Can. J. Chem. 55,3509 (1977).La co-condensation d'atomes de metaux (Cr, Fe) avec les thiophenes R (R = R' = H, Me; R = H, R' = Me) a -196"C, conduit a la desulfuration de ces derniers.Le rechauffement du compost5 co-condense thiophenefer dans un atmosphere de CO, conduit aux dtrives du tricarbonyle tricarbonylferrole-fer C4H2RRfFe2(CO),. Les etudes par rmn du 13C de ces complexes montre que la partie tricarbonylferrole est statique de -95°C a + 60°C, alors que le groupe ~c-Fe(C0)~ presente un comportement variable. L'addition de diknes ou du Me3P dans l'hexane au compost co-condenst thiophene-fer a -196"C, conduit par fusion a des solutions rouges, thermiquement instables.[Traduit par le journal]

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Section: C Nuclear Magnetic Resonance Spectra and Fluxional Behaviourcontrasting

confidence: 75%

Tricarbonylferrole iron tricarbonyl derivatives: formation from thiophenes and iron atoms in a CO atmosphere and fluxional behaviour

Chivers¹,

Timms²

1977

Can. J. Chem.

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“…Owing to the topological properties of the HOMO (eg in Oh symmetry), the ME count can vary from 20 to 24 for early transition metals and from 24 to 48 for late transition metals without significantly altering the architecture of the M6L i 8L a 6 cluster ( Table 1). [53]. In the Oh symmetry of the cluster, the orbital interaction among the six s hybrid frontier orbitals gives rise to one strongly bonding orbital a1g and five antibonding molecular orbitals (t1u + eg).…”

Section: Results and Discussion Qualitative Approachmentioning

confidence: 99%

Theoretical Investigation of Electronic Structure and Bonding in Molybdenum Face-Bridged Octahedral Clusters With Π-Donor Ligands

Nebbache¹,

Belhocine²,

Bencharif³

et al. 2012

Int J of Chem Res

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Abstract-Extended Hückel Molecular Orbital (EHMO) calculations were carried out on octahedral transition metal clusters with general formula [M6X8 i Y6 a ] (M = Molybdenum; X and Y = π-Donor Ligands) in order to rationalize their electronic structure. In these species the optimal metallic electron (ME) count is of 24 but for many clusters experimentally synthesized, the ME count can vary from 20 to 48 without dramatically altering the architecture of the octahedral cluster. Herein are reported the geometrical parameters and electronic properties, of a series of clusters with 20 to 24 valence electrons per cluster. The calculated characteristics for all the considered structures are in excellent agreement with the experimental ones and requires to learn more about the relationships that exist between their structural arrangement and electronic properties especially the number of electrons available for metal-metal bonding in M6 octahedral clusters. IntroductionTransition metal clusters exhibit a wide range of nuclearity with intriguing structural diversity [1][2][3][4][5][6]. Considerable attention attracted to the cluster compounds is caused by their remarkable properties and great technological application in many fields [7][8][9][10]. Systematic efforts aimed at understanding the electronic structure and bonding of these compounds have been initiated by several research groups by developing topological electron counting theories [3,[11][12][13]. The first Octahedral transition metal clusters with general formula [M6L8 i L6 a ] (i = inner, a = apical, relatively to Shäfer and Schnering notation) [14], have been a subject of extensive investigations because of their very interesting properties [15][16][17][18][19][20][21]. Such compounds are built up from M6L14 units (M = transition metal, L = halogen, chalcogen) in which the M6 cluster is face-capped by eight inner ligands (L i ) and six apical ligands (L a ) lie in terminal positions (see Fig. 1).

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“…exemplified. Thus, the series B,,H ,,.,, (Fe(CO),) ,-,, exists for n = 5 , 4, and 3 and they adopt the square-based pyramidal (i.e., nido-octahedral) geometry as typified (55) The situation in which chemically very different groups provide frontier orbitals of similar number, symmetry, extent in space, and energy has been skillfully exploited by Hoffmann (56,57); thus one can regard the pentacarbonylmanganese and methyl radicals as being "isolobal" (58)(59)(60), each providing a single orbital containing one electron. Likewise, a parallel may be drawn between the tricarbonylcobalt moiety and the CH fragment which each provide three orbitals and three electrons to a cluster.…”

Section: The Wade-mingos Bonding Modelmentioning

confidence: 99%

Organo-transition metal clusters: rational approaches to synthesis, structure, fluxionality, and reactivity

McGlinchey¹,

Mlekuz²,

Bougeard³

et al. 1983

Can. J. Chem.

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By using the isolobality principle, it is shown that the electronic structures of the 4- through 9-atom organo-transition metal clusters are closely analogous to the corresponding boranes. This parallelism is extended beyond simple structural similarities and is used to account for the high reactivity and nmr fluxionality of clusters which possess a vacant site on the polyhedral surface. Comparisons are also drawn with main group anionic and cationic clusters. Finally, it is shown that clusters containing gold atoms can, under certain circumstances, also follow the structural patterns of the boranes.

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Bonding capabilities of transition metal carbonyl fragments

Cited by 552 publications

References 18 publications

Tricarbonylferrole iron tricarbonyl derivatives: formation from thiophenes and iron atoms in a CO atmosphere and fluxional behaviour

Tricarbonylferrole iron tricarbonyl derivatives: formation from thiophenes and iron atoms in a CO atmosphere and fluxional behaviour

Theoretical Investigation of Electronic Structure and Bonding in Molybdenum Face-Bridged Octahedral Clusters With Π-Donor Ligands

Organo-transition metal clusters: rational approaches to synthesis, structure, fluxionality, and reactivity

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