The simple (five-parameter) force-field approximations for condensed aromatics, both for the in-plane and out-of-plane vibrations, are used to calculate the frequencies for hexabenzocoronene A (C42H18) and hexabenzocoronene B (C48H24).

Molecular Vibrations of Hexabenzocoronenes

Condensed aromatics. XXIII: Cyclo[d.e.d.e.d.e.d.e.d.e.d.e]dodecakisbenzene (kekulene)

For the uranyl 2,4-pentanedionate complex, an incomplete experimental and calculated assignment of the infrared bands have been reported [1]. In this paper, the infrared and Raman spectra of the skeletal vibrations of UO2(acac)2 were assigned. As an alternative for the purposed complete set of independent symmetry coordinates for the bis (2,2,6,6-tetramethylheptane-3,5-dionato) uranyl, for which a structure of 31 atoms has been assumed, we give here two complete sets of independent symmetry coordinates for the in-plane and out of plane normal vibrations of ML2(AA)2 type complexes of D2h symmetry. Force constants for the framework of the uranyl 2,4-pentanedionate has also been calculated. ∗ On leave from Departamento de Quimica, Pontificia Universidade Catolica do Rio de Janeiro. PUC-RIO.

Vibrational Framework Spectra of UO2(acac)2: and Symmetry Coordinate Sets for the ML2(AA)2: Molecular Model of D2h Symmetry. AA = Acetilacetonate

Framework infrared and Raman spectra of uranyl bis(1,3-diphenyl-1,3-propanedionate), uranyl bis(1,1,1-trifluoro-2,4-pentanedionate) and uranyl bis(2,4-pentanedionate) complexes

Fourier transform infrared and Raman spectra of uranyl bis(2-hydroxybenzaldehyde): UO2(sal)2

A normal coordinate analysis has been performed for bis(2,2,6,6-tetramethylheptane-3,5-dionato)uranyl according to two simplified models: (i) a 35-atom model consisting of one tetramethylheptanedionate ligand attached to uranyl; symmetry C 2 V and (ii) a 31-particle model of the whole complex, where the methyl groups are taken as point masses; symmetry D 2h . The construction of independent symmetry coordinates by the “method of fragments” is described. Calculated vibrational frequencies are reported along with mean amplitudes ( l - values) and perpendicular amplitude coefficients ( K - values) for selected interatomic distances.

A. Ischenko

Papers

Normal coordinate analysis and mean amplitudes of bis(2,2,6,6-tetramethylheptane-3,5-dionato)uranyl