Vibrational spectra and structure of the cyclopentadienyl-anion (Cp−), the pentamethylcyclopentadienyl-anion (Cp*−) and of alkali metal cyclopentadienyls CpM and Cp*M (M=Li, Na, K)

Electronic structures of organometallic complexes of f elements LXXIV: First Raman spectroscopic polarization measurements on uniformly oriented sandwich complex molecules: Bis(η5-pentamethylcyclopentadienyl)ruthenium

“…Assuming local C 5v symmetry for the Cp* ligand, and making use of correlation Table 1, the number of intra-ligand vibrations is reduced to 24 (3a 1 þ a 2 þ 4e 1 þ 6e 2 ) [8].…”

“…Essentially, three different numberings (n i ) of intra-ligand vibrations of (C 5 H 5 ) À (and thus also [C 5 C 5 ] À ) exist [7,8,19,21]. As the previously assigned vibrations for NaCp* [8] and complex 2 [7] were used here for comparison purposes, we adopt the numbering used there.…”

“…As the previously assigned vibrations for NaCp* [8] and complex 2 [7] were used here for comparison purposes, we adopt the numbering used there. Going from intra-ligand D 5h to local C 5v symmetry, the original irrep a 2 00 (n 4 ) transforms as a 1 (n 3 ) [7,8]. In…”

“…[7,8] the changed numbering is not always consequently considered. For this reason, we cite here in some cases n i s which differ from those of the original publications.…”

“…In order to separate both types of vibrations we need additional information from the spectroscopic properties of other Cp* complexes. Up to now, normal coordinate analyses (NCAs) of the vibrational spectra of only MCp* (M ¼ Li, Na, K) [8], Cp*M(CO) 3 (M ¼ Mn, Re) [9] and Cp*ReO 3 [9] have been performed. Besides, the unassigned far infrared (FIR) and Raman spectra (in the range below 520 cm À1 ) of both powdered and dissolved material of RuCp 2 * (1), OsCp 2 * (2) and FeCp 2 * (3) were reported [7].…”