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The Versatility of Pentalene Coordination to Transition Metals: A Density Functional Theory Investigation
Author(s) -
Bendjaballah Saïda,
Kahlal Samia,
Costuas Karine,
Bévillon Emile,
Saillard JeanYves
Publication year - 2006
Publication title -
chemistry – a european journal
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 1.687
H-Index - 242
eISSN - 1521-3765
pISSN - 0947-6539
DOI - 10.1002/chem.200500765
Subject(s) - pentalene , allylic rearrangement , chemistry , polyene , ring (chemistry) , density functional theory , crystallography , valence electron , transition metal , valence (chemistry) , ligand (biochemistry) , double bond , metal , single bond , computational chemistry , stereochemistry , molecule , electron , physics , organic chemistry , catalysis , biochemistry , receptor , alkyl , quantum mechanics
DFT calculations with full geometry optimization have been carried out on a series of real and hypothetical compounds of the type [CpM(C 8 H 6 )], [(CO) 3 M(C 8 H 6 )], [M(C 8 H 6 ) 2 ], [(CpM) 2 (C 8 H 6 )], [{(CO) 3 M} 2 (C 8 H 6 )], and [M 2 (C 8 H 6 ) 2 ] (M=transition metal). The bonding in all the currently known compounds is rationalized, as well as in the (so far) hypothetical stable complexes. Depending on the electron count and the nature of the metal(s), η 2 (predicted), η 3 , η 5 , η 8 , or intermediate coordination modes can be adopted. In the case of the mononuclear species, the most favored closed‐shell electron counts are 18 and 16 metal valence electrons (MVE). In the case of the dinuclear species, an electron count of 34 MVEs is most favored. However, other electron counts can be stabilized, especially in the case of dinuclear complexes. Coordinated pentalene should most often be considered as formally being a dianion, but sometimes as a neutral ligand. In the former case it can behave as an aromatic species made of two equivalent fused rings, as a C 5 aromatic ring connected to an allylic anion, or even as two allylic anions bridged by a C7C8 double bond. In the latter case, it can behave as a bond‐alternating cyclic polyene or as a C 5 aromatic ring connected to an allylic cation.