Reactions of laser-ablated chromium atoms with dioxygen. Infrared spectra of CrO, OCrO, CrOO, CrO3, Cr(OO)2, Cr2O2, Cr2O3 and Cr2O4 in solid argon

Abstract

Reactions of laser-ablated Cr atoms with O2 gave a very strong, sharp 965.4 cm−1 band and weak, sharp 1869.7, 984.3, 914.4, 846.3, 716.2, and 643.1 cm−1 bands. The 1869.7, 965.4, and 914.4 cm−1 bands track together on annealing, show 52Cr, 53Cr, 54Cr isotopic splittings appropriate for a single Cr atom and triplets with statistical 16,18O2 for two equivalent O atoms, and are assigned to the ν1+ν3, ν3 and ν1 modes of the bent (128°±4°) chromium dioxide OCrO molecule. The 984.3 cm−1 band shows chromium isotopic splittings for two Cr atoms and 16,18O2 components for two O atoms, and is attributed to the bent CrOCrO molecule. The weak 846.3 cm−1 band exhibits proper oxygen isotopic behavior for CrO and is redshifted 39 cm−1 from the gas-phase value, the maximum shift observed for a first row transition metal monoxide. The sharp 716.2 and 643.1 cm−1 bands track together; the former reveals Cr isotopic splittings for two Cr atoms and the latter 16,18O2 splittings for two sets of dioxygen subunits; the branched-puckered-ring dimer O(Cr2O2)O is identified. Annealing produces new bands due to CrOO, CrO3, Cr(OO)2 and the ring dimers (Cr2O2) and (Cr2O2)O, which are identified from isotopic shifts and splitting patterns.

A Critical Appraisal of the Experimental Data on the Molecular Structure and Spectra of Halides, Oxides, and Hydrides of the s-, d-, and f-Block Elements

“…The results were obtained by reaction of laser-ablated metal atoms with oxygen followed by cocondensation with argon to give a matrix that could be studied by spectroscopy. The resulting bond angles (given here without error ranges) show an interesting dependence on the central element: Ca [85] 1408, Sc [86] 1288, Ti [87] 1138, V [88] 1188, Cr [89] 1288, Mn [90] 1358, Fe [91] 1588, the rest (Co [92] , Ni, [93] Cu, [94] Zn [95] ) linear. There is, not unexpectedly, a dramatic change in the simple valence force field (SVFF) stretching force constant derived from n Ä 3 for CaO 2 ).…”

Franck-Condon simulation of the anion photoelectron spectroscopy of CrO2 by coherent state method

“…In Chertihin and co-workers' experimental study [8], both chromium and oxygen isotopic shifts of the antisymmetirc stretching frequency of CrO 2 (X 3 B 1 ) were involved in determining the O-Cr-O bond angle, we considered that their experimental value 128 ± 4 • was more reliable, thus we chose this value as the criterion to assess the calculated values in this work. As shown in Table 2, for the density functionals O3LYP1, B3LYP, B3PW91 and OLYP, almost all calculated bond angle values are within the range of 124-132 • reported by Chertihin [8], except the value of 132.10 • at the B3LYP/aug-ccpVDZ level. With regard to the density functional PBE1PW91, only the value of 130.68 • calculated with the LANL2DZ basis set is within the range of 124-132 • , the remaining calculated values obtained with other four basis sets are all higher than the upper limit of 132 • .…”

“…Since the intensity of the peak corresponding to the symmetric stretching mode is much weaker than that for the antisymmetric stretching mode in matrix IR spectroscopy [6,8,9], it is difficult to determine the symmetric stretching frequency accurately using the matrix IR spectroscopy. The experimental value of 895 ± 20 cm −1 obtained from the high resolution NIPES reported by Wenthold [10] was chosen as the criterion to assess the theoretical values of 1 .…”

“…As shown in Table 1, two studies have determined the O-Cr-O bond angle of CrO 2 (X 3 B 1 ). In detail, Alomond and co-workers [6] have obtained a bond angle of 112 ± 2 • , while Cherichin et al [8] have measured a larger value of 128 ± 4 • .…”

“…Chromium dioxide is widely used in magnetic recording tapes and other magnetic layers, and therefore its properties in bulk phase have been well known [1,2], meanwhile a number of studies [3][4][5][6][7][8][9][10][11] have focused on the isolated CrO 2 molecule at the X 3 B 1 ground state with the purpose of determining the vibrational frequencies and the O-Cr-O bond angle. These studies are summarized in Table 1.…”