title: Calculated and experimental geometries and infrared spectra of metal tris-acetylacetonates: vibrational spectroscopy as a probe of molecular structure for ionic complexes. Part II.
abstract: Following on from our previous work on Sc, Fe, Cr, and Al (Part I; see J. Phys. Chem. A, 105 (2001) 238), the geometries and infrared spectra of the trivalent metal tris-acetylacetonate complexes (M[O2C5H7]3; M = Ti, V, Mn, Co) have been studied both experimentally and theoretically using nonlocal hybrid density functional theory with a split-valence plus polarization basis for the ligand and valence triple-zeta for the metal. Unlike the D3 complexes studied in Part I, those of Ti, V and Mn are candidates for Jahn-Teller distortion due to fractional d-shell occupancy. Using scale factors transferred from Part I, our calculated frequencies are in very good agreement with experimentally observed fundamentals. Our investigation shows that the V and Mn complexes distort to C2 ground states, but D3 Ti tris-acetylacetonate is stable. Further investigation of the weak band observed around 800 cm(-1) in the Fe complex (and present in almost all studied first-row transition metal tris-acetylacetonates), which we were unable to assign theoretically in Part I, supports the argument that this band is not a fundamental but is due to Fermi resonance.
authors.affiliation: Department of Chemistry and Biochemistry, University of Arkansas, Fayetteville, AR 72701-1201, USA.
authors.forename: Irina
authors.initials: I
authors.lastname: Diaz-Acosta
authors.forename: Jon
authors.initials: J
authors.lastname: Baker
authors.forename: James F
authors.initials: JF
authors.lastname: Hinton
authors.forename: Peter
authors.initials: P
authors.lastname: Pulay
mesh_terms: D007477:Ions; D008670:Metals / Q000737:chemistry*; D010422:Pentanones / Q000032:analysis / Q000737:chemistry*; D013055:Spectrophotometry, Infrared / Q000379:methods*
chemical_list: D007477:Ions; D008670:Metals; D010422:Pentanones; C008790:acetylacetone