title: Solvent-dependent resonance Raman spectra of high-valent oxomolybdenum(V) tris[3,5-bis(trifluoromethyl)phenyl]corrolate.
abstract: UV-visible, infrared (IR), and resonance Raman (RR) spectra were measured and analyzed for a high-valent molybdenum(V)-oxo complex of 5,10,15-tris[3,5-bis(trifluoromethyl)phenyl]corrole (1) at room temperature. The strength of the metal-oxo bond in 1 was found to be strongly solvent-dependent. Solid-state IR and RR spectra of 1 exhibited the MoVO stretching vibration at nu(MoVO)=969 cm(-1). It shifted up by 6 cm(-1) to 975 cm(-1) in n-hexane and then gradually shifted to lower frequencies in more polar solvents, down to 960 cm(-1) in dimethyl sulfoxide. The results imply that stronger acceptor solvents weaken the MoVO bond. The 45-cm(-1) frequency downshifts displayed by 1 containing an 18O label in the molybdenum(V)-oxo unit confirmed the assignments for the observed IR and RR nu(MoVO) bands. The solvent-induced frequency shift for the nu(MoVO) RR band, measured in a series of 25 organic solvents ranging from n-hexane (AN=0.0) to N-methylformamide (AN=32.1), did not decrease in direct proportion to Gutmann's solvent acceptor numbers (ANs). However, a good linear correlation of the nu(MoVO) frequency was found against an empirical "solvent polarity" scale (A+B) of Swain et al. J. Am. Chem. Soc. 1983, 105, 502-513. A molecular association was observed between chloroform and oxomolybdenum(V) corrole 1 through MoO...H/CCl3 hydrogen-bonding interactions. This association manifested itself as a shift of the nu(MoVO) RR band of 1 in CDCl3 to a higher frequency compared to that in CHCl3.
authors.affiliation: Department of Chemistry, University of Houston, Houston, Texas 77204-5003, USA. roman@uh.edu
authors.forename: Roman S
authors.initials: RS
authors.lastname: Czernuszewicz
authors.forename: Vicky
authors.initials: V
authors.lastname: Mody
authors.forename: Adelajda A
authors.initials: AA
authors.lastname: Zareba
authors.forename: Marzena B
authors.initials: MB
authors.lastname: Zaczek
authors.forename: Michał
authors.initials: M
authors.lastname: Gałezowski
authors.forename: Volodymyr
authors.initials: V
authors.lastname: Sashuk
authors.forename: Karol
authors.initials: K
authors.lastname: Grela
authors.forename: Daniel T
authors.initials: DT
authors.lastname: Gryko