Ligand effects on the electronic structure, spectra, and electrochemistry of tetracobalt carbonyl clusters

Journal Article · Wed Apr 16 04:00:00 EST 1986 · J. Am. Chem. Soc.; (United States)

DOI:https://doi.org/10.1021/ja00268a028· OSTI ID:5583031

Holland, G F; Ellis, D E; Trogler, W C

Self-consistent field X..cap alpha.. calculations using the discrete variational method (SCF-X..cap alpha..-DV) have been performed for Co/sup 4/(CO)/sub 12/ (I) and the C/sub 3nu/ symmetry model clusters (eta-C/sub 6/H/sub 6/)Co/sub 4/(CO)/sub 9/((PH/sub 2/)/sub 3/CH) (III), and (eta-C/sub 6/H/sub 6/)Co/sub 4/(CO)/sub 6/((PH/sub 2/)/sub 3/CH) (IV) to explore the effect of phosphine and arene ligands on cluster electronic structures. Density of states plots have been used to simplify analysis of bonding trends in these complex clusters. The cluster core charge varies from 3.11, to 2.58, to 2.41, to 1.80 e along the I-IV series. Charge on the apical Co is least positive in the arene-capped cluster II while basal cobalts are least positive in IV. Ionization potential calculations support qualitative Hueckel studies that suggested (eta-C/sub 6/H/sub 6/)M fragments bind more strongly to other metal centers than isolobal M(CO)/sub 3/ fragments. Electronic absorption spectra of I, (eta-MeC/sub 6/H/sub 5/)Co/sub 4/(CO)/sub 9/(tripod) (VI) (tripod = (PPh/sub 2/)/sub 3/CH), (eta-MeC/sub 6/H/sub 5/)Co/sub 4/(CO)/sub 6/(tripod) (VII), and (eta-C/sub 6/Me/sub 6/)Co/sub 4/(CO)/sub 6/(tripod) (VIII) exhibit low-energy features between 1000 and 400 nm. Arene-capped clusters exhibit an extra low-energy absorption and calculations for the models II and IV assign this to a HOMO-LUMO transition that resembles intramolecular charge transfer from the apical to basal cobalt atoms.

• Research Organization: Northwestern Univ., Evanston, IL
• OSTI ID: 5583031
• Journal Information: J. Am. Chem. Soc.; (United States), Journal Name: J. Am. Chem. Soc.; (United States) Vol. 108:8; ISSN JACSA
• Country of Publication: United States
• Language: English

Related Subjects

37 INORGANIC, ORGANIC, PHYSICAL, AND ANALYTICAL CHEMISTRY
400301* -- Organic Chemistry-- Chemical & Physicochemical Properties-- (-1987)
400400 -- Electrochemistry
ABSORPTION SPECTROSCOPY
CALCULATION METHODS
CARBONYLS
CHEMISTRY
COBALT COMPLEXES
COMPLEXES
DATA
ELECTROCHEMISTRY
ELECTRONIC STRUCTURE
EXPERIMENTAL DATA
INFORMATION
IONIZATION POTENTIAL
LIGANDS
MATHEMATICAL MODELS
NUMERICAL DATA
PHOSPHINES
PHOSPHORUS COMPOUNDS
SPECTROSCOPY
TRANSITION ELEMENT COMPLEXES