The electronic structures of bis(η⁶-benzene)- and bis(η⁶-naphthalene)chromium(0)

Abstract

. SCF MS X a molecular orbital calculations are reported for the bis(q"benzene)-and bis(q6-naphthalene)chromium (O) complexes. The bonding may be essentially discussed in terms of the covalent interactions between the metal 3d and ligand .rr and .rr* orbitals. The different charges on chromium atom in the two systems are explained by the different balances between ligand-to-metal (bonding) and metal-to-ligand (back-bonding) electron donations. Some resemblances are found between the electronic structures of the two compounds and it is possible to correlate to a large extent the energy levels of their molecular orbitals. However, a shift towards lower values is predicted for the energy levels of the naphthalene complex, together with a large disruption of all the virtual .rr* and 3d* levels. This would undoubtedly favor nucleophilic attack followed by metal-ring or carbon-carbon bond cleavage, in agreement with the extreme lability of the coordinated arene rings observed in this complex.JACQUES WEBER, E. PETER KUNDIG, ANNICK GOURSOT et EDOUARD PENIGAULT. Can. J. Chem. 63, 1734Chem. 63, (1985.On a effectuC des calculs d'orbitales molCculaires MS Xa en champ autocohCrent pour les complexes bis(q"benzkne)-et bis(q6-naphtal&ne)chrome(0). On peut decrire la liaison dans le complex presque essentiellement l'aide des interactions covalentes entre les orbitales 3d du metal et les orbitales T et T* du ligand. On explique les diffkrentes charges sur l'atome de chrome dans les deux systemes par des bilans differents entre la donation directe d'klectrons ligand-mCtal et la rCtrodonation mCtal-ligand. Toutefois, on prCdit un dkplacement vers des valeurs plus basses pour les niveaux CnergCtiques du complexe de naphtalene ainsi qu'un mClange important de tous les niveaux virtuels .rr* et 3d*. Ceci devrait de toute evidence favoriser une attaque nuclCophile, suivie d'une rupture de la liaison mCtal-cycle ou carbone-carbone, en accord avec la labilitC extrCme observke dans ces complexes pour les cycles areniques coordonnCs.[Traduit par le journal]

Density Functional Study of Metal−Arene Compounds: Mono(benzene)chromium, Bis(benzene)chromium and Their Cations

“…The magnitude of the electron transfer compares well with previous MSXα calculations of Weber et al . , (0.60 or 0.86 electrons) and Osborne et al (0.94) but deviates somewhat with King et al . results (1.28) who found more pronounced electron migration from the chromium to the ligands.…”

Actinide arene-metalates: ion pairing effects on the electronic structure of unsupported uranium–arenide sandwich complexes

“…2,3 In Cr(h 6 -C 6 H 6 ) 2 , the molecule features a formally chromium(0) atom sandwiched between two neutral benzene rings wherein stabilization is bidirectional: donation of the benzene p-electrons into empty metal orbitals accompanied by backbonding of occupied metal orbitals into the empty benzene p*-orbitals. 4,5 This contrasts the bonding scheme in Cp 2 Fe (Cp ¼ h 5 -C 5 H 5 ), which is considered to contain an iron(II) centre sandwiched between two p-donating, anionic, aromatic Cpligands with negligible backbonding character. 6 Indeed, subsequent analysis of the bonding in Cr(h 6 -C 6 H 6 ) 2 suggests that chromium d-backdonation is the largest contributor to the bonding interactions.…”

Triberyllium cluster sandwich complexes: A density functional investigation

“…The bonding in bis(η 6 -benzene)chromium(0), as determined at the SCF MS Xα level of theory [38] and more recently at the BPW91/TZVP level of theory [39] may be most easily and simply described in terms of covalent interactions between the π and π* ligand orbitals of the C 6 H 6 groups and the 3d, 4s, and 4p orbitals on the chromium center. In a similar fashion, the bonding in bis(benzene)triberyllium(0) -as indicated by the molecular orbitals which involve significant Be-C interactions (Fig.…”