Les liaisons triangulaires changent les perspectives de la chimie

Greenwood, N. N.

doi:10.1016/s1631-0748(03)00010-9

Cited by 3 publications

(1 citation statement)

References 24 publications

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“…The question of the precise origin of such interactions is an interesting one but it may be yet another reflection of the remarkable coordination chemistry of the proton, a chemistry much better known under the title of 'hydrogen bonding' [59]. It is also reflected in chemistry such as 'bridge bonding' in boranes [60] and 'agostic'interactions of transition metal complexes [61], and once again it is possible that biology may eventually provide the stimulus to reconcile seemingly disparate aspects of the chemistry of a given element.…”

Section: Discussionmentioning

confidence: 99%

Biological coordination chemistry, a confluence of chemistry and biochemistry

Harrowfield

2005

Comptes Rendus. Chimie

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Section: Discussionmentioning

confidence: 99%

Biological coordination chemistry, a confluence of chemistry and biochemistry

Harrowfield

2005

Comptes Rendus. Chimie

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Sandwich Compounds of Transition Metals with Cyclopolyenes and Isolobal Boron Analogues

Gribanova

Starikov

Minyaev

et al. 2010

Chemistry A European J

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A series of sandwich compounds of transition metals (M=Ni, Fe, Cr) with cyclic hydrocarbon (M(CH)(n)) and borane (M(BH(2))(n)), ligands (including mixed hydrocarbon/borane sandwiches) has been studied using density functional theory (B3LYP/6-311+G(df,p)). Multicenter bonding between the central metal atom and basal cycloborane rings provides stabilization to planar cycloborane species. Large negative NICS values allude to aromatic character in the cycloboranes similar to the analogous cyclic hydrocarbons. The ability of cycloborane sandwiches to stabilize attached carbocations, radicals and carbanions is also assessed.

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π-Complexes of transition metal tricarbonyls with cyclopolyenes and their boron analogs

2009

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ul. Chekhova, 344006 Rostov on Don, Russian FederationThe structures and stability of complexes of transition metal tricarbonyls (M = Co, Fe, Mn, Cr) with hydrocarbon and borane basal rings, (C n H n )M(CO) 3 and (B n H 2n )M(CO) 3 , respec tively, as well as internal rotation of the metal tricarbonyl fragments in these systems were studied by the DFT B3LYP/6 311+G(df,p) method. Replacement of hydrocarbon basal frag ments by isoelectronic borane rings leads to strengthening of the interaction between the apical and basal fragments, but does not change the trend in the heights of barriers to internal rotation. In all cases, the metal tricarbonyl fragment stabilizes the nonclassical planar form of the borane rings, whereas the complexes of metal tricarbonyls based on the classical nonplanar borane conformations are less thermodynamically stable.Key words: transition metal tricarbonyls, metalloboranes, stereochemical nonrigidity, quan tum chemical calculations.π Complexes of transition metal tricarbonyls with cy clopolyenes (C n H n )M(CO) 3 have been well studied. 1,2 To date, various 18 electron complexes (C n H n )M(CO) 3 (n = 4-8) with apical groups containing transition metals from Ti to Ni have been synthesized and structurally char acterized. Such compounds possess high thermal stability and are stereochemical nonrigid due to almost free rota tion of the metal tricarbonyl group about the symmetry axis. A salient feature of these systems is the possibility for induced aromaticity to occur. 3 For instance, the interac tion of the Fe(CO) 3 group with the antiaromatic cyclo butadiene fragment in complex 1 stabilizes the square con figuration of the basal ring with equalized carbon-carbon bond lengths. Compound 1 exhibits characteristic aro matic properties; this made it possible to introduce the term "metalloaromaticity". 4,5The first metallaborane synthesized was ferraborane 2 (Scheme 1) in which the cyclobutadiene ring is replaced by borane. 6 This compound is isostructural and isoelec tronic to the hydrocarbon analog 1. Similarly to the cy clobutadiene fragment, which is stable in the rectangular form with alternating bonds (system with equalized bonds is unstable), the planar four membered borane ring B 4 H 8 is also unstable and has a boat structure in the free state.Thus, the Fe(CO) 3 group stabilizes not only the sym metrical form of cyclobutadiene, but also the nido form of isoelectronic borane B 4 H 8 , which does not exist in the free state. 6-8 This leads to a new stable metallaborane 2.At present, investigations of such systems that relate the chemistry of boranes to organometallic chemistry and co ordination chemistry is a topical avenue of experimental and theoretical research, which offers prospects for the discovery of novel compounds with unusual structures and properties. 6-8One can expect that stabilization of other borane rings B n H 2n (n = 3, 5, 6) by the corresponding metal tricarbonyl fragments will lead to a new family of metallaborane sys tems 3-5 isoelectronic and isostructural to the t...

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Les liaisons triangulaires changent les perspectives de la chimie

Cited by 3 publications

References 24 publications

Biological coordination chemistry, a confluence of chemistry and biochemistry

Biological coordination chemistry, a confluence of chemistry and biochemistry

Sandwich Compounds of Transition Metals with Cyclopolyenes and Isolobal Boron Analogues

π-Complexes of transition metal tricarbonyls with cyclopolyenes and their boron analogs

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